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MG MGA - Engine temp reduction question

I have a 1960 MGA coupe (1600) with air conditioning. The A/C condenser is mounted directly in front of the radiator and uses a pusher fan to force air through it...the normal radiator fan is still being used to pull air through.

In stop and go traffic without the A/C on the engine temperature runs about 190 (87c) degrees, with A/C on it's about 212 (100c). When running between 3000 and 3500 rpm the temperature increases to between 212 -220 (100 - 105c) degrees, with the A/C on at these RPM's the engine temperature creeps up to 225 (107c).

Yesterday my wife and I were returning from a car show and since it was late, decided to return via the interstate. Max speed on the interstate here in Mississippi is 70 mph but you can stay in the slower lane with no problem at 65 mph - which I tried to do. Running at this increased speed raised the engine temperature to 225 and made running the A/C almost impossible - engine temps kept creeping up slowly to 230 (110c) so I'd have to shut it off every 4 or 5 minutes or so and let the engine cool - which it did fairly quickly.

It appears I need to either find a more efficient radiator for better cooling and/or fit either an MGB transmission with O/D or a 5-speed to lower the rpms.

Right now, because of the A/C, I can't use an MGA radiator because the input on the left side interferes with the pulleys so I'm using an MGB engine water outlet and a new MGB radiator with MGA radiator brackets soldered on it so it is firmly bolted in place.

A couple of questions here and I'm looking for ideas/suggestions/opinions. Do you think I can I get sufficient cooling by having a high efficiency radiator core installed in this MGB radiator OR should I bite the bullet and buy an aluminum radiator? I know Barney doesn't like aluminum radiators but from everything I read on the internet (bible - smile) they are efficient. Should I try to find/install an MGB overdrive transmission to lower the rpm's? What about a 5 speed? Or should I do both - radiator and transmission swap? What the hell, it's only money!

As I said, thoughts appreciated.
Gene Gillam

I am only guessing, but surely an overdrive would only reduce the revs, not the amount of heat generated by the engine doing the same amount of work?
One of the big problem with MGAs is encouraging air to travel through that relatively small grille, and an awful lot of heat seems to get trapped under the bonnet (hood). I wonder if louvred inner wings, like the Twin Cam has, might help, or possibly louvres in the bonnet to give all that hot air somewhere to go.
Lindsay Sampford


I agree with Lindsay, try for a better air flow first.
That is the cheapest option.
I would do a trial run with the front grille removed.
The mga twin cam louvered panels in the wheel arch work well, but they have to be the double punched type (punched from both sides).
I would not put louvers in the hood (bonnet) unless you are sure whether the air passing over the hood generates a positive or negative pressure.
An aluminum radiator will not help unless it has a superior core design. Copper and brass disperse heat better than aluminum.
Higher gearing for lower RPM will not help as more throttle opening is required to pull the higher gear.
The same power is always required at the rear wheels for a given speed.

M F Anderson

In my experience new radiators are not that good at cooling, so I would take the original and have it recorded with a nice open core that lets the air through well. Some high performance radiators seem to make things worse in an MGA. Also check that you have the right cap for the radiator, because if it doesn't seal and hold pressure you will loose coolant and overheat.

I would also try without the radiator grille, and if that brings an improvement then go for a mesh instead of the slats.

Having a five speed box DOES help, because the engine is working much less to keep you moving. If the revs come down, so does the heat - you are burning less fuel as well.

I would also try decalcing the coolant passages, muriatic acid is the stuff, but it's fairly vicious stuff and will fizz like mad, so leave the cap off the radiator if you do this and do it outside where the fumes can escape and be ready to drain and flush through. I guess that most engines have never been cleaned this way, or not cleaned when being rebuilt, so the coolant passageways are blocked at the rear of the block.

I run a Judson on a fairly warmed over engine and a five speed box, and run constantly at 73C (for those still working in old money that is 164F).
dominic clancy

Depending on concentration, muriatic (hydrochloric) acid is viscious stuff, and attacks iron, so dilute it and don't leave it in long!!
Much safer are organic acids found in commercial rad cleaners, and they do work.
Art Pearse

I can see I left out some important information above.

Temperatures here in Mississippi from May to November are generally between the mid 70's to mid 90's with HIGH humidity. The temperature the other day was mid 80's.

Prior to the A/C installation the car ran consistently at 180 (82c). After installing the A/C we experimented with the grille opening and found that a chrome mesh grille provided the best cooling - that's what's there now...with the normal grille in place the temp was almost 200 (105c).

I have thought about using the "Twin Cam" louvered panels but need a source...anyone know where I can purchase them?

Thanks for your thoughts!

Gene Gillam

I would consider repositioning the air con heat exchanger underneath the radiator duct and fit it with a small electric fan which only comes on when the a/c is switches on. Davies-Craig make a range of small cooling fans that you should be able to fit.
Then all the heat from the a/c unit isnt exhausting into the cars radiator and causing problems.

A small diameter automotive fan will draw up to 5 amps once it gets up to speed and so your cars charger system should cope fine with the extra load.

This would save you an awful lot of work and experimentation.

c firth

autovintagery sells the panels
dominic clancy

Colyn - I think I may do that in conjunction with changing the radiator out.

Since we don't use the heater here I was considering adding a small additional radiator at the rear of the car using the heater connections. Does anyone know if there's enough circulation in the system to make that feasible?
Gene Gillam

Gene, it looks as if your MGB radiator is coping fine with cooling the engine when the A/C is switched off.
So fixing the a/c unit under the radiator duct panel should solve the problem.

I only just realised that your a/c compressor has its own built in fan and so it should work fine under there.

I have fitted my oil cooler under the duct panel and it is working well. I did cut a vent in the front valence to increase airflow to it but your a/c compressors own fan means that you dont have to do that.

I think an additional small radiator positioned at the rear of the car would work using the heater hoses to supply it. You may have to build in bleed valves at the higher points of the piping to prevent air locks.

To be honest though, once you re-position the a/c compressor I dont think you will need it.

c firth


If you are considering using the Twin Cam type louvered panels in the front wheel arch be sure to use the correct type.They must be punched in both directions.
The manufacturer of the best panels is Kilmartin Sheet Metal in Australia. They have distributors in the USA. Email them for your nearest Dealer.

I cannot load images at the moment. There seems to be a BBS website problem.

M F Anderson


I ordered the Kilmartin louvers this afternoon direct...$165 including shipment to the dealer here for these.

Gene Gillam

Okay...did some checking here today.

Mick (above) has been corresponding with me this week giving suggestions and today I tried some out.

There is no blanking sleeve in with the thermostat and the antifreeze/water mixture looks clean as anything. I ordered the blanking sleeve today from LBC (Jeff Zorn). I contacted the guy who I'd worked with on the A/C installation since I was sure we'd changed the thermostat at that time and he said he never uses the blankers with the modern thermostats...doesn't think there's enough flow bypassing the radiator to make a difference. Moss seems to think so, so does Mick. I'll see when it gets here.

After buttoning the thermostat back up and refilling the lost fluid I put the bonnet back down and started the car. I ran it in the garage at 3700 rpm and watched the thermostat open at what looked like 185dF (85C), drop down a bit and then, creep up to 190dF (87.77C) where it steadied out. I held it at 3700 rpm for another couple of minutes then turned on the heater...didn't seem to make a bit of difference on the temp gauge. I then turned on the A/C, keeping the revs at 3700 rpm. It took over 5 minutes for the temperature to reach 218dF (103.3C) where it pretty much settled out, maybe would have crept higher but the garage was getting hot so I stopped the test.

What does that tell me? Not sure. It definitely proved that the fan is pulling air thru the radiator since it doesn't overheat while idling or while the engine is revving high when there's no load on it other than the A/C compressor.

Is there too much air being trapped in the engine compartment at speed? It appears to be but hopefully the new inner fender louvers will help eliminate some of that trapped heat.

One thing I'm sure would help would be to move the A/C condenser from in front of the radiator because I'm pulling the heat from it thru the radiator but there's just not a good place to put it that I can see.

Will a new radiator help? Hate to spend $500 on a state of the art aluminum radiator that may not help that much.
Gene Gillam

I would move that AC condenser to the underside of the shelf. MGAs run hot enough as it is because of the tiny engine bay and poor air flow through the grill. Introducing hot air across the lower third of the radiator is certainly not helping matters.

The fact that it overheats only when the AC is on, regardless of load, points right at that condenser in my opinion.
Steve Simmons


I do not think that running the engine in the garage is a conclusive test. You need to do checks with the air flow when the car is being driven.
I see your situation as the main problem being the A/C condenser and it's fan being situated in front of the radiator. Not only is the air flow to the radiator obstructed but also the condenser is passing warm air through the radiator.
The suggestions being given are to marginally offset this problem.
Definitely block the bypass tube with a sleeve if you are using a modern non-sleeved thermostat. You can do a check by just blocking the bypass tube at one of it's hoses, while waiting for a blanking sleeve.
The wheel arch louvers may help but do not expect a great change.
I do not recommend aluminum radiators, they are no better, even worse, than copper/brass.
The best radiators are the V-Cell type.
These are made in New Zealand and sold by The Filling Station in Lebanon Oregon USA.
A V-Cell core is shown on page 300 of their online catalog. Be aware that V-Cell radiators require good coolant quality as they are hard to clean. They cannot be "rodded" as with tube in matrix type.
You would need to fit your MGB tanks to the core.
M F Anderson


Steve's suggestion seems to the best, easiest and cheapest so far.
Save a lot of money by moving the A/C condenser to under the shelf (with no fan). Many MGA owners put their oil cooler there.
Cancel any order for a new radiator until you try the move.

M F Anderson

Hello Gene - you mention above that you were also considering using a MGB overdrive gearbox in your A. From what I have read and seen, the MGB overdrive gearbox is far too large to use in your A. The modern 5-speed conversions seem to be the better option. The cutting and modifications required to fit the MGB overdrive unit seem excessive to me.

Best of luck to you with your cooling issues.

Let us know what you find out once you are back on the road.

J Delk

Mick and J Delk,

Will let you know what turns out to be the key...going to try one thing at a time until it's corrected.

Gene Gillam

Okay...inner fender louver installation complete...and tested!

Do inner fender louvers help reduce under bonnet temperature/engine temperatures. YES!

After bolting the louvers in place I took the car out for a spin. At a steady 70 mph without A/C the car hit 205 and stayed there for 7 miles. I then turned on the A/C and continued at 70 mph - I was able to go 20 miles before the engine temperature hit 228 dF at which time I slowed down to 65 and the temperature dropped back to 225 dF. I stayed at 65 for 5 more miles, then dropped the speed to 60...the engine temperature dropped to 215 and stayed there. I have NEVER been able to run the A/C this long at almost any speed without being at the 220 - 225 mark.

The thermostat blanking plate came in the mail this afternoon so I'm going to install it tomorrow morning and give it another run to see if that will also cause temperature reduction.

Now the ambient temperature this afternoon was only 81 but I've been in cooler weather running a lot hotter at these speeds.

Gene Gillam

Louver test fit...

Gene Gillam

And ready to go:

Gene Gillam

What is the temp outside when you are driving and your temp is holding 164 degrees. I wish my car ran at your temp with my Judson Supercharger. I would love to climb hills and go for drives in the mountains and hold even 180 degrees.

Jeff Becker

This year the highest ambient temp when driving passes was 38c, and engine temp reached 85c

That's 100F and 185F respectively

Temp reaches 100c / 212f or higher with heat soak once the engine is switched off. The gauge is accurate at that temp.

But if timing or mixture are off, overheating is guaranteed. Richer mix is better, especially for a supercharger.
dominic clancy


Remember when you fit the blanking sleeve the small holes in the sleeve should not face the rectangular bypass port.
You may be able to fit the sleeve with the modern thermostat (non movable sleeve type).
If you cannot fit both at the same time try running the car without a thermostat in the short term.

M F Anderson

Here I go again; that's a high general free running temperature even without the A/C on and a high ambient temperature. What is the radiator history? I would be surprised if it has an MGA standard core in it.

Steve Gyles


Will do - the blanking sleeve has 4 equally spaced holes around it - it may be a bit hard to line it up perfectly unless I solder one of the holes closed.


As mentioned above, it has a brand new (Moss) MGB radiator modified to take MGA side flanges so it's bolted in securely.

Before the A/C installation, with the MGA radiator it ran in the low 180's max.

Gene Gillam

Installed the blanking sleeve today - I soldered one of the 4 holes shut so I could make sure I was blanking off the exit. Engine temperature was almost an exact repeat of the experience with the inner fender louvers, in other words, I couldn't tell there was any difference with or without it. After a steady 3900 rpm/70 mph the temperature just kept climbing to 235 dF. Slowing down to 65 mph the temperature would drop to 225 dF and stay there, dropping further as the speed slowed.

There was a difference today in that I took my wife and we had a full tank of gas so the engine had to work a little harder but other than that the outside temperature was about the same.

My wife did mention that the cabin along the transmission tunnel and at the feet was a lot cooler than before, I'd noticed that yesterday but forgot to mention it here. I do believe the inner fender louvers are worth the effort.

Next will be new radiator!
Gene Gillam

Hi Gene - sounds like progress!

I would still take a look at your timing advance - could you advance the timing for another high speed run and see what you get? Even if you have problems at the lower end of the range, an improvement at upper speeds would tell you that you need a revised advance curve and max advance setting.

I also wonder about fuel delivery at the needle settings for your upper speeds.

These issues sure keep you thinking at night don't they?!


You are running out of options.
The photo of your A/C condenser shows that it would not fit under the shelf in front of the radiator.
If buying a radiator talk to the experts about different types - standard core versus aluminium versus V-Cell types.
See image.


M F Anderson

DLD, timing has been checked and rechecked...over and over. Dead on.

Mick, I'm still debating on what to use. I was reading Barney's site about the pros and cons of using the original V-cell core ( and I remember the problems I had with my stock radiator back in the 60's.

I did look at the link on Barney's site for Maine Auto Radiator and found this: (

If this would fit the radiator I've got in there now I may be willing to try it.

Gene Gillam

On the Maine Radiator site, click on Antique, then look at Vintage/Classic/Antique, and click on Antique Core Types. Click for the larger image. The one you want is Cellular, being the cell core for the original MGA radiator. It works.

Barney, I clicked on the High Performance link and called them about that. They can't/won't talk price to me but will to the radiator shop I use. They did say that they can make what ever I need so I took the car to a shop I've used in the past and they're willing to work with Maine Auto. I'll pull the radiator this week and take it down to them.
Gene Gillam


That link to high performance on the Maine radiator site is about replacing modern plastic tanks with metal type.
I assume that you have metal tanks already.
What you need is a more efficient core.
Discuss cell type cores with your radiator shop.
A more efficient core is likely to be your only solution.

M F Anderson

Gene, -- Don't let the radiator shop tlk you into a "High Performance" vertical tube core. It will have too many tubes and too many fins to close together and it will obstruct air flow. The key character of this setup is rising coolant temperature at higher road speed.

You need the original type Cellular radiator core.

I recently got a quote from our local radiator repair shop for a recore with a cellular core and it was £400 including tax. This is a lot of money especially as I had had a tube and fin recore from the same shop about seven years ago costing just over £100. The owner told me at the time I would get a big improvement with the T&F but he was wrong.
However splashing out £400 could be an expensive gamble so I've just bought a very cheap s/h cellular core radiator off Ebay for a comparison test when we get the next 25 degree day. It's unlikely to be this year now!........................Mike

PS On receiving the cellular core rad. it is very noticeable how much more 'open' the core structure is compared with that of the T&F.

m.j. moore

Removed the radiator (remember, it's a new Moss MGB radiator) and took it to the radiator shop. I also took an MGA radiator with me so the shop owner could see (and feel) the difference in weight between the two. And, just for good measure I took an mga top tank with the core removed so he could see that too.

The MGB radiator is a good 7 pounds lighter than the MGA radiator. I understand that's because of how they're made but it's amazing that there is that much more material in the original radiator (fins, solder) than in the MGB radiator. Additionally, the MGB core is 1/4" thinner than that MGA radiator and is very "see thru".

The shop owner is going to call Maine Auto Radiator and talk to them about a replacement core for the MGB radiator. He knows I'd prefer the V-cell if it's available and if he can get it to fit the mgb top and bottom tanks...I'm pretty sure it will since they both fit in the MGA.

Gene Gillam


You have already stated that your radiator is working ok and that the overheating only occurs when you have the air con unit running in front of it.

Like I (and a few others) have said earlier, I think the answer is to place your a/c heat exchanger somewhere else.
It already has a fan built into it and so it is not critical where you put it so long as there is some constant ventilation to it.

Ideally beneath the radiator duct would be best as there is indirect airflow there. It may fit under there sideways on and at a slight angle do that air can flow up into it,ideally with the fan on the side where any airflow is coming from.
It doesnt really need direct airflow as it has its own fan for this.

If it is too big to fit under the radiator duct, maybe you could source a smaller heat exchanger that will fit into that space, there must be something suitable out there somewhere.


c firth

I might chime in here briefly if you'll indulge me. (Just saw I wasn't so brief after all! Sorry!)
There's no doubt that with its crowded engine bay, and tight clearances for air to get away, the design and performance of the radiator core in an MGA is much more critical than with most other cars, such as say the otherwise closely related MGB.
The MGA's cooling with an original MGA "cell core" (aka "V cell") radiator is usually perfectly satisfactory. Contemporary road tests made no mention of problems, no ex dealership or factory employees recall any issues, and those who've retrofitted an original style core are, to my knowledge, happy with the results.
The question however is whether even a cell core style radiator will cope when faced by pre-heated hot air passed through the a/c condenser.
Is there indeed a possibility of re-siting the condenser, even with a custom made unit to fit the size and shape of the space available under the duct panel, as others have suggested? I'd have thought an angled mounting beneath would be an excellent option to explore.
If this truly is not an option, then I fear the other alternative may prove to be a custom made radiator from a reputable manufacturer (as opposed to a local radiator shop)..
When I had major issues with my conventionally re-cored radiator, and not realising at the time that v cell cores were still available (for us in Australia from New Zealand), I worked in with a company in Queensland called PWR who design and manufacture radiators for performance cars including NASCAR and Formula 1. (Indeed the majority of their production is for export). We came up with a compact (slightly smaller than original, and a hell of a lot lighter), simple and relatively cheap custom design that performs remarkably well.I hardly ever even glance at the gauge now, and (unlike with a/c), I haven't required additional fans other than the standard engine driven fan (and a shroud).
The Australian dollar is way down compared to other currencies just now (one Aussie buys a measly 70 US cents). Maybe an email to PWR might just be worth the effort. I have absolutely no doubt they could configure a radiator to meet your requirements. Australia is a hot country, and apart from a few classics like MGAs, all cars have air conditioning.
Mine is here:
T Aczel

Tom, read your radiator article earlier on the MGA Guru site. There are several shops here in the States that can make me one if I need it - thankfully my wife likes the car and will let me make a few monetary mistakes before I solve the problem.

I agree with everyone that moving the condenser coil is the answer however it won't fit neatly either above or below the front shelf. out of the way of the radiator. It's the smallest A/C condenser I can find (10" X 18" approx, not including hoses)...if someone is aware of something smaller please let me know!

I still haven't heard back from the radiator shop...I was expecting something by yesterday but nope. I'll call Monday and see what's going on.
Gene Gillam

OK, thinking outside the box, why not put louvres in the front wing splash panel and mount the condenser there?

Colin Manley

I suspect that there would be too much damage to the condenser by stones thrown up by the wheel.

M F Anderson

Snooping around from the T site... I use a dimpled 4 row copper core in my TF that a local shop did for me using my existing tanks. Now that I have a tickler pin t-stat in there to bleed the air better on a refill, I can't even get to temp unless it is a really hot day (before the tickler pin t-stat, it was able to make temp). I've been quite impressed with this cores performance.

Alex Waugh

Alex, Please give us some more info re the "dimpled 4 row copper core". Overheating is a problem here in Aus. due to high summertime temperatures. Photos?

Barry Gannon


I am not sure what Alex has but it sounds like four rows, front to rear, of vertical water tubes passing through the fin matrix.
I have changed many Triumph cars from three rows to four rows and it has helped. However, I do not think it will help Gene. With his A/C condenser he already has too much airflow restriction.
A more efficient V-Cell core seems his best solution.


M F Anderson


I have a great deal of experience in matters like this, having operated an automobile facility in Scottsdale, AZ.

I have a few suggestions. It would be helpful to know the ac pressures - high side and low side - as well as the discharge temperature of the evaporator. Sometimes going to a 70 or 80% charge will still provide ample cooling, but lower the high side (condenser temperature and pressure) dramatically.

Of the one picture I was able to see, the condenser design looks very restrictive I would suggest moving the condenser away from the radiator, angle it into an "A" shape and add a duct at the bottom of the splash pan to supply additional air to the radiator. Also, a fan shroud on the engine driven fan would be of huge benefit.

If you mounted the condenser as I have described, you may be able to fit a larger condenser with a more open matrix. Also, are you absolutely sure the electric fan is blowing through the condenser? I have seen it happen before.

Feel free to call me - I will do all I can to help you.

Gregory S
La Grange, Il
(708) 715-5517
GMS Serduke


Thanks for your comments. Right now I'm waiting on the radiator shop to call me back (STILL!!). I've found a supplier for the v-cell core that Mick recommends and given it to him but he still hasn't checked back with me on a cost.

There is really limited room in front of the radiator to do much but I'll see if I can angle the condenser - I did think that the condenser had to be close to the radiator to reduce swirling of the air...maybe not???

I can hear the fan turn on so I know it's blowing - and I have no problem until I get close to 70 mph and 4000 rpm.

Gene Gillam

The fact that the overheating is worst at high speeds makes me inclined to check two simple things before you change the radiator out.

1. As Gregory says, check that the fan is blowing in the right direction and not sucking hot air through the engine radiator and passing it through the condenser. I recently rewired a car for a friend and got (only this) the wiring reversed on the radiator fan, which caused MUCH hotter running. That you can hear the fan running is only part of the diagnosis, you need to check which direction it is blowing.

2. How does it behave if you richen the mixture a few flats on each car. My thinking here is that with the extra load on the engine from the compressor, it may be running a little too lean, which will induce an overheating problem.
dominic clancy

Gregorys offer sounds like a no brainer to me, you should give him a call Gene, it could save you a lot of effort.

The problem with all MGAs is that at high road speeds, not enough air can escape through the engine compartment. So there is just not enough airflow through the radiator to cool it.

On my MGA which is fitted only with twin 9" electric fans and also twin cam style, louvred inner wing vents, I recently noticed a similar situation.
I was driving at 70mph + in ambient temperatures of 70 degrees and the temperature gauge was climbing beyond 195 degrees. Out of curiosity I maintained the speed and switched the twin fans on. The temp very quickly dropped to 165 degrees and stayed there so long as the fans were running. It kind of proves that you do need some sort of fan on an MGA engine at high road speeds.

So it is no real surprise that when you add your A/C unit in front of the rad, it makes things worse still.


So if you cant move the A/C unit underneath the radiator duct, then the only other thing I could think of is to try to move your radiator forwards as far as possible and then see if this then would free up enough space to fit the A/C condenser behind it.

That is, assuming that it would still work sufficiently well in this warmer position? What do you think Gregory?

You would have to remove the engine driven fan to help increase the space and fit two 9" electric fans onto the front of the radiator like I did to cool the engine.

It should be possible to reverse the A/C units fan blade on its spindle so that it would then suck air through it.

So, using this set up, none of the exhaust heat from your A/C unit would then go through the radiator which could solve your problem.

Freeing up enough space to do this is the main challenge with this idea, but if you can, I think it would do the trick.

( NAMGAR are publishing my findings on electric fans -single and twin fans- in next months MGA Magazine I think)


c firth

Colyn's assertion that all MGAs have heat problems isn't at all true. I know of many that have no problems at all, and in summer it gets just as hot here and in northern Italy as it does in the southern USA. And charging up a mountain pass certainly gets the engine working hard. The airflow is fine if everything is in good order.

I can cruise all day at high speed (10 hours from here to Calais at a steady 80 mph two years ago in temperatures of 38C / 100F for example), and I know Steve Gyles has similar average running temperature experience.

In winter I have to close the radiator blind in front of the radiator to get up to operating temperature on a cold day, otherwise the coolant doesn't warm up even to 50C at all. This is the same whether running with Supercharger or not.

My personal belief on the causes of high running temperatures are in order
1. cooling passages in the engine are all gummed reducing efficiency
2. wrong radiator core or blocked radiator
3. weak mixture
4. worn distributor causing over advance at high revs
5. timing set incorrectly for unleaded fuel

I reckon fitting of extra fans is addressing the symptom rather than the cause. The only exception is the bilge blower to stop fuel evaporation when standing in traffic, bit I do my best to stay out if that!

dominic clancy

I see what you are saying Dominic but I didnt actually say that I think all MGAs have heat problems, I just said that I believe the MGA doesnt flow air as well through the radiator when travelling at higher road speeds as it does at lower speeds.

When I had an engine driven fan fitted it usually ran between 165 and 185 degrees depending on the ambient temp. Like yours it struggled to reach 150 on cooler winter days. On scorching hot summer days it would run up to almost 195 occasionally if I was pushing it hard and but would cool down very quickly when I slowed down.

So my cooling system is pretty good.

Last year I chose to remove the engine driven fan and replace it with twin 9" electric fans running on a thermostatic switch to see if my cooling system would cope like this. I hoped that the car would run cool enough most of the time for the fans to stay switched off.

As it turned out, I have found that the car still runs between 175 and 185 degrees and the engine only gets warm enough for the fans to switch on when it is in standing traffic.

So I dont advise running with an extra fan.

I just prefer to run my car with fans that only run 5% of the time rather than with a continuously running engine driven fan that is mostly running for no reason.

My main reason for this is that a couple years ago I had my car set up on Peter Burgesses dyno and he commented that the high performance plastic fan I was using at the time was using up as much as 5bhp!

My MGA does run approx 10 degrees cooler at higher road speeds when it has an engine driven fan fitted than it does with no fan running at all.

But at higher road speeds with electric fans fitted, I found that when I accidentally switched the fans on, the temperature dropped nearly another 20 degrees.

So it seems to run cooler at higher road speeds with either an engine driven fan or an electric fan running than it does without a fan.

Hope that makes some sense,and explains why I think there may be some possible use for electric fans in Genes set up.


c firth

Having done high mileage in my A in the early 70s I never suffered heat problems or vapourisation hence I have a feeling a lot of this is to do with modern fuels. By the way my engines were mainly high mileage even if obviously much newer.

Paul Dean

Hi Colyn

I apologise if I have interpreted your comments incorrectly, but I still question the comment

"The problem with all MGAs is that at high road speeds, not enough air can escape through the engine compartment. So there is just not enough airflow through the radiator to cool it."

This isn't my experience at all, and I do drive at the legal limit for long stretches (10 hours with just short toilet breaks on that trip to Calais, and the same on the return to Zürich, both days hot enough to raise the hood to get some shade...).

This summer I also borrowed a twin cam and had a (new) starter fail, so had to keep going to return the car to its owner - up the Stelvio, and a over number of other passes (couldn't take the short cut on the train to Klosters because I couldn't restart the car - no starter handle) and then a fast run from Davos to Landquart, then highway to Zürich. 40C ambient, hot as Hades on the Autobahn (again roof up for shade and 120kmh for the whole one-hour trip back) and the gauge stayed steady at 170F.

Paul and Steve's experiences match mine pretty much I think.

I reckon fuels in Switzerland are pretty much the same mix as everywhere else in Europe, so I question whether fuel can be the culprit, although the timing retarding needed to compensate for the use of unleaded fuel (this was the subject of much discussion as lead was based out) have been forgotten, and the hot-running cars could perhaps be fixed by simply retarding the timing by two or three degrees instead of using the handbook setting (which is designed for leaded fuels.)

Which means you are in part correct to blame modern fuels, but the fix is easy and doesn't involve any engineering changes.

With a bit of luck Peter Burgess will chip in, and hopefully not tell me I'm talking garbage (but if he does I know better than to argue!) For my engine (with PB head) I run the settings given by Chris Betson and don't ask any questions at all. And I can run all day at whatever speed I like, whatever the ambient temperature, and the needle stays steady as long as I am on the move.

dominic clancy

Maybe I should have worded that sentence a little differently Dominic.

I probably should have just begun it with "It has been my experience that".

Or, "Most MGAs except Dominics, Steves and Pauls!" :-)

In my defence I did ask an awful lot of MGA owners about their experiences with their temperature gauge and even Barney has written in MGA Guru that his car can get "nervously close to 230 degrees" on long climbs in really hot weather. He uses the heater control as an emergency extra cooling sytem.

On our trip last year to the Pyrenees I was in a group of 3 MGAs making our way down to the Mediterrean French / Spanish border in temperatures of 40C (104F).

We were driving at a steady 80mph on a long climb on the motorway and my temp gauge was showing in the high 190s.
My car has an 1850 mgb engine but the other 2 cars were a standard 1600MkII and a standard 1600, both in great condition.

Their gauges were showing well over 200 degrees and at our next fuel stop they suggested that maybe we should slow down a little.

All three cars showed a drop of 10 degrees on their gauges when we slowed to between 65 and 70 mph and mine was the coolest of the three.

Dominic, I would be interested on your thoughts on this.

Why on a hot day, my does my MGA run much cooler whilst climbing a long motorway climb if it has either an engine driven fan or an electric fan blowing into the radiator than it does if there is no fan at all?

You would think that the 70mph airflow would be sufficient by itself.

It will be interesting to see how my twin-electric fans cope with the 1950cc engine that I am hoping to fit over the winter!

Sorry Gene, you can have your thread back now!

(Attached a pic of my twin fans)

c firth

Colyn, Your comment struck a chord with me:
"I probably should have just begun it with "It has been my experience that".
Or, "Most MGAs except Dominics, Steves and Pauls!" :-)

Out for a run last night in 28C temp -- moderate traffic, top speed regulated at 80kph. and dial sat on 190 and quickly got to 212 when stopped at lights. A slight improvement when out of 'stop/start' traffic.

I run an electric fan as well as the motor fan and have a new MGB radiator fitted and an oil cooler mounted below the gravel tray. Motor has been flushed.
Heat radiation from tunnel is uncomfortably high.

Help! Barry.
Barry Gannon

Just wondering, but did all these problems occur in the 60's 70's etc.? Would love to know if there were similar comments being made back then...if not, it is the modern fuels and additives!
Gary Lock

Probably less to do with the modern pseudo-gas than it has to do with the modern phony radiators.

D Rawlins


I am not sure you can say that with certainty. Back in th 60S and 70S a lot more cars would also have still been on their ordinary cored rads.

Steve Gyles

My gauge would be showing about 185 degrees in those temperatures Gary and up to 195 when in traffic.
When I had just an engine driven fan I fitted an upgraded plastic fan and it instanly dropped the temp by 10 degrees compared to the std metal fan.

It was the NTG fan and it was excellent but noisy.
Apparently, the Moss asymmetric plastic fan is good too and much quieter running.

Its a pity we are not nearer, you could borrow my old NTG fan to try.
Neil Ferguson in Oz has a spare one too.

c firth

My thoughts would be that it runs cooler with a fan because that's how the experts at MG designed it to work. I am no expert on air flows so I'll defer to the experts on any theory there.

I run an engine fan, and always will. It works well, and is really simple.

I reckon that adding supplementary fans is just attacking the symptoms of the overheating rather than addressing the cause. The probable causes in my book are those I listed.

I suspect that many cars are overheating because they are a little lean or running with a little too advance, or both. A little adjustment on these can bring a big improvement on running temperature.

And I can only repeat I have absolutely no cooling problems at all, and AFAIK the same holds true for the 40-odd cars in our local club. Some do have supplementary fans fitted, so I'll have to start asking how many of them are actually pressed into service and how many are relics from previous owners.

I also need to start asking the fan users where the radiator came from. One of my MGA owning friends has (at my suggestion) just had his original radiator recored to the same (bog standard MG) spec as mine, and reports much better cooling than with the Moss thing he had in before. Before it was running too hot and the fan was running a lot. This mirrors other experiences with repro radiators in other cases - once a 10€ eBay original that looked terrible was used in desperation to try to get to the bottom of a severe overheating issue, and once it was in the problem was immediately resolved and attributable to the brand new Moss unit we had just taken out.

dominic clancy

I'm thoroughly enjoying this thread while I'm waiting on the radiator shop to get back to me.

I can comment on MGA's back in the 60's. I re-enlisted in the Navy in 1965 and used my reenlistment bonus to buy a used 1962 MGA - this was out in California. Shortly after buying it I received orders to Danang, Vietnam so I decided to drive it across the USA to North Carolina where my family was. Before doing so I had the car tuned and had the radiator rodded clean (at least I paid for it to be done!). I drove north from the San Francisco area where I'd been driving it, climbing in altitude as I went. By the time I hit Nevada the car was severely overheating, I was having to pull over every 20 miles or so and let it cool down so I could drive a bit further. Spent two days of the trip trying to get out of Nevada - finally found an old repair shop and tried to get some help. The guy drained some water from the radiator and put in about 3 bottles of radiator flush and we headed out into the desert to see what would happen. Car ran as cool as it had ever run so we went back, drained the radiator, put in fresh water and away I went - for 20 miles where it overheated again. I was finally able to limp into a service station where I bought 5 bottles of radiator flush, filled the radiator with it, and set out again. I NEVER had another bit of trouble, even in the mountains of Colorado, so I left the flush in the radiator. My sister had the car while I was in Vietnam and she never had any problem with it either...well, until she wrecked it, but that's another story.

So yes, back in the 60's I know of at least one newish MGA that ran hot.
Gene Gillam

Leaving A/C aside for the moment, like Gene I find this thread (and endless similar ones) interesting reading. But the thing is that the problem of MGA engine temperature issues was solved quite some time back. The dominant factor, assuming all other things to be within spec, is the radiator. The newer style cores just don't appear to work well in an MGA.
It gets dammed hot in Australia. (41C/106F predicted for where I live today!!) Despite this, and with just a standard engine driven fan plus shroud, I have NO OVERHEATING PROBLEMS. I have yet to see over 195 on my gauge since replacing my original but recored radiator, despite using the car in temperatures up to 38C/100C. (Even I wouldn't be crazy enough to venture out into traffic today!) Before the radiator changeover I'd be seeing 215 and even more on the gauge.
I think many have come across my summary of my own findings which has been on Barney's Guru site for a few years now, but just in case some haven't, and at the risk of many (again) disagreeing with my deductions here it is:
This still hasn't solved some fuel vaporisation issues when switching off on hot days and restarting a few minutes later. (The car runs, but pops and farts for about 20-30 seconds). Preferring to avoid a bilge blower fan, I've sent my exhaust manifold off for jet coating which should help both with this problem, and likely reduce engine bay and therefore cabin temperatures a bit.

T Aczel

Yes Tom I have read your article quite a few times and pretty much agree with all of it.

I seem to have stirred things up with my theory that the airflow through an MGAs radiator tends to be much reduced at high road speeds because it struggles to escape through the cramped engine compartment at those speeds.

I recall that at the beginning of your article, you compare the cramped MGA engine bay compared with the much more spacious MGBs as a factor in its cooling. Also that the MGAs radiator grille is actually larger than that of the MGB but this doesnt seem to help.

You may have seen that I have swapped the engine fan for two 9" electric fans which come on when the gauge gets to 205 degrees. It really does work well and it only cuts in when I am crawling in traffic and it rapidly brings the temp down to 190 which I can live with.
As my car normally runs between 175 and 185 degrees in summer, this means that the fans only really come on when the car is stationary.

Neal Ferguson in Oz gave me the idea of using twin fans, he leaves them running constantly and this keeps his car cool even in the high temperatures there.
I wanted to use this idea on my car but didnt want the fans running continually as they were using up 5% of the engine bhp.

Tom, what do you think of my discovery that my car runs cooler on hot days and at speeds over 70mph when it has either a std fan OR an electric fan drawing air through the rad?

The 2 main differences that I can see between Dominics cooling system and mine (apart from the fans) is that-
(1) I have a standard grille whilst his has stainless mesh.
(2) I have louvres at the rear of the bonnet but Dominics has none.
( I do have a radiator from Bob West)

The louvres may well allow air to be forced into the engine compartment at high speed as your article suggests. This may be causing higher pressure inside the engine compartment. (But they do allow more air to escape from the engine bay when I am stopped with the engine running, I can actually see it rising out of them)

I will have experiment to see what happens to the temperature if I drive the car with the louvres taped up and let you all know.

Also, Dominics grille mesh well may be allowing a larger flow of air through the radiator than my standard type grille does.

I will also put that on my "things to experiment with next" list.

NAMGAR have just published in MGA magazine the results I have written up of "My experiments so far" with Plastic Fans, a Single Electric Fan and now, Twin Electric Fans.

This thread may well make me update it further.


c firth

Tom, I have downloaded your/Barney's reference, thanks for that, will look at it over the weekend.

Colyn, can we have a photo of the louvres please.

Barry Gannon

Stopped by the radiator shop today and the owner had been in contact with Maine Auto Radiator. He described what I have now to them and they say their new core will be 30 - 40% more efficient. Its going to be expensive (total cost of core/labor will be about $450) but I told him to get it on order. Hoping to have it back by the middle of December. It will be too cold here to give it a true test but I have high hopes.

I was very impressed by the temperature reduction brought on by the inner fender louver installation...hopefully this will be equally effective.
Gene Gillam

"Tom, what do you think of my discovery that my car runs cooler on hot days and at speeds over 70mph when it has either a std fan OR an electric fan drawing air through the rad?"

Hi Colyn.
I just had a look at your twin electric fan installation.
I'd hazard a guess that even without the fan blades, your two fans (motors, frame, mounts and cables) sitting as they are against the front of the radiator, would be obstructing air flow to about 20% of the surface area of the leading face of your radiator. The effective air flow obstruction to the radiator all up, including the fan blades would be even greater, as, while the fan blades will spin with the on-coming air flow, they would still cause a degree of additional air flow obstruction. (Just imagine the air flow with the fan blades cut off).
Consequently, I think, it is not altogether surprising that you have found that even at higher road speeds you find you have greater air flow still, and therefore additional cooling, with your fans running.

With my standard engine driven fan (+shroud), around 90% of the time I can actually see the temperature gauge oscillating slightly as the thermostat opens and closes. The effect is still apparent even at higher (80mph plus) road speeds (when I can, rarely, manage such speeds without attracting the attentions of our militant Australian speed limit enforcing constabulary!!).
My temps only creep up a little with prolonged idling in heavy traffic on hot days when fan speeds and therefore airflow across the radiator, and coolant flow through the radiator are both significantly slowed. But even then I don't believe I've seen over 195F with my current installation. (Alloy custom rad, shroud/engine driven fan and (factory fitted) 10 row oil cooler).
T Aczel

I fitted a stainless mesh a couple of years ago as a Summer experiment, it took 10 - 15 degrees of the running temp, so it does show that entry of air is more of an issue than exiting of hot air. I quite liked the look of stainless mesh.
Colin Manley

Thanks for that Tom
Before I first looked at fitting twin fans I asked Neil Ferguson if his twin fan set up caused any problems due to their masking the radiator.
He replied that they didnt seem to, but I hadnt realised at the time that he ran them continuously and therefore masking wasnt an issue.

The Davies Craig fans I have fitted are quite slim and it may be possible to fit them behind the radiator, or at least one of them.
This would help prevent any masking and it may be something else to put on my "things to experiment with next" list. I will let you know if it helps.

Barry, I will see if I can attach a pic of the louvres on my car. Tom suggested that they may well be reducing the airflow through the rad and so I wouldnt cut any metal until I have run my car with the louvres taped up.
This should prove if they have any worthwhile beneficial effects.

The consensus until now is that if you cut louvres in your MGAs bonnet, they should be nearer the front of the car in a low pressure area so that the hot air can escape when the car is at speed.

Louvres at the front of the bonnet would also still allow hot air to escape when the car was stationary so maybe this is a better position for them.

Thanks for the input everyone, lots to think about.


Pic from this years MGA Day, hope you can see the louvres Barry.

c firth

If nothing else, Colyn, those louvers look great!
Gene Gillam

Of course, on older MG's and other makes, the louvres faced forward to scoop air in....

Colin Manley

The mesh grille doesn't make any difference to running them in my case. I just prefer the looks

dominic clancy

I thought I should more clearly explain that my engine temperature reaches 205 degrees when in traffic by intent and not because it is suffering from cooling problems.

The main reason for this is that my fans thermostatic switch has a 15 degree range (hysteresis) between switching on and off. So if I set it to switch on at 205 degrees it will then run for a couple of minutes until drops to 195 and then switch the fans off.

The gauge usually shows a max of 185 and so when the car is moving it is below the fans operating range.

(It is initially quite scary to see just how fast the temperature rises when there is no engine driven fan fitted)

I would prefer to fit a thermostatic switch with a 10 degree range so that I could perhaps set the on temperature at just below 200 and so it would switch off at just below 190 but I haven't managed to find one yet.

I suppose this is because I am more comfortable when the gauge shows under 200 than when it goes above it.

However, I am fairly sure that the engine would be perfectly happy running up there than I am! :-)

c firth

Since my name has been mentioned above as being a cool runner - 175 all day regardless of speed, it's probably worth the mention that I run the sports screen with a more raked (Le Man's) stanchions. I guess this alters the pressures over the bonnet and may be a contributing facture to the cooling. Otherwise I run a standard MGA cored radiator, normal engine driven fan and no shroud. My air conditioning is the wind through my hair. With the revised screen rake etc I cannot fit a hood nor side screens.

Steve Gyles

Even if your car ran hotter than 175 Steve, I would always think of you and your MGA as "Cool Runners"!

c firth

"The consensus until now is that if you cut louvres in your MGAs bonnet, they should be nearer the front of the car in a low pressure area so that the hot air can escape when the car is at speed."

It surprises me, repeatedly, how many of us ignore the fact that the factory development engineers were talented, (chosen from amongst their many aspiring peers), full time professionals and with all the facilities of the works and their suppliers laid on. Their choices were well considered and sound. So despite "enhancements" one often sees by the amateur backyard "expert" based just on on intuition, such as "bigger must be better" (HS6 instead of HS4 carburettors, oversize inlet ports, wild grind camshafts etc etc) the factory choices for most of our purposes were pretty close to spot on.

As for the location of bonnet louvres should one wish to use them, despite a more rearward location looking "right" and "cool", the attached photo is interesting as it shows how far forward the Competitions Department chose to place the MGB bonnet louvres. (I have seen, but was unable to find today a photo of probably the same car with the bonnet closed, which shows the relatively forward location of the louvres even better).

T Aczel

Tom, thats why I wrote "IF you cut louvres".

Although I do like the look of the louvres on my car, I have to admit that I probably wouldnt have them if they hadnt had been already on the car when I got it.

My car also came with lowered and stiffened suspension which I also really like the look of.
It corners on rails on a really smooth road surface, but on a bumpy road (like most around where I live) the ride can become so harsh that I have to slow down to save my fillings from falling out!
In other words, I would probably be able to drive the car faster most of the time with a stock suspension set up.

So yes I have to agree that MG probably got the suspension set up, the cooling system and most of the other stuff right from the start.

I do plan to put the suspension back to something like standard at some point in the future, probably when common sense overtakes the fact that I think the car looks so cool with lowered suspension. :-)


c firth

Thanks for the photos - I know a fellow who has a louvre cutting and shaping press - all I have to do is decide the location - then if I really want to go down that path!

I have the felt seal fitted over the radiator, so if I choose to cut up near the forward point (nose) - where do the louvres go? In front or behind?

Barry Gannon

Barry, I'd be VERY CAUTIOUS about putting LOUVRES into your MGA bonnet.
Firstly it is unnecessary. Your car's cooling can be improved by simpler and cheaper means.
Secondly, the results are far from easy to predict, even with some modicum of air flow knowledge. Yes the louvres, were you to fit them, should be behind your radiator, and most definitely not in front.
At a standstill, there is no doubt that hot air would exit the engine bay through the louvres, just as it does through the two oval shaped shroud vents. The difficulty is predicting what happens with forward motion of the car, and indeed at different speeds.
In theory the ideal location would likely be between half way and two thirds of the way along the bonnet. What we don't know without testing however is whether even in these locations, at speed, the air flow might actually be the reverse of your intentions, with air entering rather than exiting the engine compartment, just as it does through the two shroud vents, the precise opposite of what you'd wish to achieve in your circumstances. (Higher engine bay air pressures will inhibit the flow of air through the radiator core, and it it is your radiator which cools the engine. The engine bay air temperature is close to irrelevant to coolant temperatures).
Here's two of the conclusions from wind tunnel testing of an MGA published in 1964:
2- The high-velocity air passing beneath the car reduces the pressure within the engine compartment to the extent that it is lower than the pressure on the hood.(i.e. "bonnet" for us in Australia).
3- The air outlets on the hood are located in a position at which air pressure outside the hood is greater than inside and results in air flowing in rather than out.
T Aczel

So "To louvre or not to louvre, that is the question, whether 'tis nobler to leave your bonnet unmolested?"
Dont think thats quite what the Bard said but the question remains.

Barry, I probably wont be able to get any sensible answers to the question until the spring, its down around zero here and the car (and me) just wont get warm enough to see.
When the weather is warmer I plan to tape up the louvres and do a fast run, then repeat the run without the tape.

If the car does run cooler at high speeds with the louvres taped up I will have to come up with something similar to Dominics radiator blind. Or maybe a set of slotted vane shutters that slide under the louvres to open them in traffic and close them at speed. :-)

The way this is going I am going to have to make sure that I always travel with a riding mechanic like in the veteran racing car days, who can operate all these extra controls. :-)

Barry, I seem to remember that a number of your fellow Aussie End to Enders had louvres on their MGAs bonnets.
Maybe if you offered to supply them with a few "tinnies" and a roll of Duck Tape, they may run this experiment for you?

But like Tom says, dont do anything to your bonnet until you are sure it will help the cooling process.

c firth

Thanks Tom and Colyn I don't intend doing anything just yet but I'm happy to roll this question along and see what pops up. The wind tunnel testing Tom refers to is the sort of discussion I think we need.
I will have the electronic dizzy checked first then maybe lean it off a bit and then reassess before any drastic action.

Many thanks, Barry.
Barry Gannon

More out of curiosity than need, back in the summer I fitted the felt pad over the radiator - it made absolutely no difference to the running temperature at a all. Is that another myth busted?
dominic clancy

Point taken Dominic, and you may well be correct.
I do wonder however whether we can by glancing at the temperature gauge during varying driving conditions detect with accuracy the benefit derived from modifying one single more minor "peripheral" item. Similarly I'd wondered whether Colyn's planned testing by blanking off of his bonnet louvres in hotter weather will yield reliable results.

My own impression, simply from personal experience, was always that the dominant factor, in an otherwise correctly tuned MGA engine, in respect of coolant temperatures is primarily the performance of the radiator core, with additionally, in low speed/heavy traffic conditions and an engine driven fan, the presence of a radiator shroud.
The original cell core (aka V-cell) style radiators, I believe, the Bob West supplied radiators, and good quality modern design aluminium radiators all seem to perform well in an MGA application.
The more minor contributions such as provided by the radiator blanking, an original style deeper thermostat, or alternatively a blanking sleeve, probably together add further benefit. Additional elements such as an expansion tank can add further gains to comfortable trouble free day to day running in hot weather and heavy traffic.
From my own experiences in an often hot country however, where I no longer have any overheating no matter the circumstances, the major gains were derived from changing the radiator and adding a shroud. Popularly used additional items such as supplementary electric fans and bonnet louvres have proved to be unnecessary, at least for me.
T Aczel

My own view is that all to many owners address the symptons rather than the root cause. i.e. putting a sticking plaster over a graze while the heart still bleeds internally. As Tom mentioned, Bob West found a good supplier to recore his radiators close to original spec with excellent results. Mine is one of his. I have mentioned before that I lent my rad to a colleague with overheating problems. He had gone the full monty: opened the grill; oil cooler; felt pads; and electric fan, all to no effect. He installed my radiator and got an instant 20 degree drop.

My case rests.

Steve Gyles

gIven that the cool runners all have radiators to original spec, can the hot runners perhaps say where their radiators came from and what spec they are? That may prove to be very enlightening.
dominic clancy

I second that Dominic. May be a new thread that we can all log our data, then do the analysis when we have a sufficient sample.

Steve Gyles

Could someone with a real knowledge of radiator design describe the technical advantages of a "V Cell" design? I am just curious as to what actually makes them more efficient.

I have one of the original radiators in my spares pile and I guess I should treat it with more respect from now on!

Curious as to the actual design advantages - and if they are so efficient, why was the design not carried forward - did the MGBs use a V cell?

I have enjoyed reading the thread - but am sorry Gene is having his issue.

I used to be a member of the "Cool Runner" club myself Steve (175) degrees)but since I replaced the engine fan with thermostatic twin electric fans I have moved into the "Cool-to-Slightly Warm Runner" section! (175 to 185 degrees)

I do have a Bob West sourced original spec radiator fitted.

However, if I leave my electric fans running continuously the gauge never rises above 165 degrees and so I could therefore be eligible to be included in a "Super Cool" section, which sounds rather cool! :-)


c firth

Colyn, while as always I'm happy to be corrected (I'm just a mere amateur, and interested observer), I suspect that running your car at temperatures of 165 and below may well be counterproductive to performance and perhaps even to engine longevity. While cooler intake air certainly leads to a denser charge and enhances performance, (more combustible substrates of air and fuel vapour per intake cycle makes for "bigger bangs"), my understanding is that engines will similarly "make a bigger bang" when operating at higher temperatures, that is, in the specified normal range.
Similarly engine oils are designed to function best in normal operating temperature ranges.
Dominic and Steve, I agree that an MGA fitted with an original spec radiator (and indeed, with everything to ex-factory spec) tends to run close to the desired range, there remains "more than one way to skin a cat". Even Bob West's radiators are, I believe, unless he's now modified the design from a few years back, not to original V cell design, but relies on a non-staggered tube design. And Bob told me in an email about three years ago, that for a Le Mans replica car he was preparing, he was resorting to an aluminium radiator for enhanced cooling under such particularly arduous conditions. With my own aluminium radiator 90 plus% of the time, in hot "arduous conditions Australia" I'm sitting right on the thermostat set coolant temperature.
T Aczel

Sorry Tom,
my last post was fueled by my warped sense of humour (some would say weird!):-)

I would never let my electric fans run continually as I agree that 165 is too cool for an B Series engine (or any engine) and would probably result in reduced engine life as well as reduced performance.

My engine temperature with only the twin electric fans fitted usually runs at between 175 and 185 except in traffic when it rises a little higher, which triggers the fans to switch on.

My experiments with electric fans are intended to discover if the MGA can safely operate with cooling fans that only operate when the temperature rises to a higher level rather than operating continually like the standard engine driven fan does.

This was instigated when Peter Burgess told me that the high performance engine driven fan that I had fitted was using over 5% of my engine power. So my theory was that if the engine fan was removed it would give my engine a 5% increase in performance.

The results so far have proved that they can do this as the fans only run when the car is in standing traffic and in occasional conditions of extreme heat at high road speeds.

So my fans only run for maybe 5 to 10% of the time.

I have some more things to try with the thermostatic control system of my fans to fine tune things a little more but I am confident that they will become a permanent fixture.

If Im not totally happy with the twin fans performance at the end of this experiment I can always refit an engine driven fan and admit defeat!


c firth

Tom, If you are a willing you could probably help me sort my heating problem with a chat on the phone. Can you please contact me at:

Cheers, Barry
Barry Gannon


Firstly a description of the various radiator types that have been mentioned.
One type has a series of rows of vertical water tubes that are fixed to, and pass through, a matrix of fins. The heat is transferred from the tubes to the fins and then the fins are cooled by the air.
There are usually three or four rows of tubes.
The tube rows can be in line viewed from front to rear or staggered.
I believe that in line is best because the staggered rows obsruct the air. It must be remebered that air past the fins, not air past the tubes, does the cooling.
The advantages of this type are that they are cheap to make and the tubes can be cleaned by "rodding".
However, they are not very efficient. Heat transfer from the points where the tubes touch the matrix is quite low.
With a V-Cell you have a double sided flat metal ribbon that is bent back and forth many times as it goes from the top to the bottom,
This is repeated with several vertical ribbons and the whole thing is soldered together.
This is extremely efficient with a large suface area of metal with water on one side and air on the other.
The disadvantages are that they are complex (expensive) to make and are heavier, and difficult to clean.
In the end the accountants have won out over the engineers. We even now have most radiators with plastic tanks !!

(see image)

M F Anderson

Another advantage to the V cell radiator that I've not seen mentioned elsewhere Mick is that they actually hold a lot more water in their matrix than the amount of water present at any point in time in a series of tubes in a modern conventional style radiator. And this larger volume of water is in contact with a much larger surface area of the heat radiating part of the matrix as you also have just implied.
So despite them being labelled sometimes as "old fashioned" v cell (cell core) radiators are in fact a very good design for a radiator.
Their disadvantages are precisely as you say, plus for many, difficult availability.
I was quoted very recently $1420 for a V cell radiator core from my local Natrad branch, plus labour to fit it to my radiator top and bottom tanks. My PWR aluminium hi tech radiator, which I estimate weighs less than a third of a conventional brass unit, cost about $850 all up, and performs its task remarkably well.
My recored staggered three row tube radiator that came with the car when I bought it on the other hand performed dismally. I couldn't get to the top of my long climb home in summer without boiling over on switching off. I'd be seeing 220-225F on the gauge quite often in summer.

And Barry Gannon, I've sent you an email tonight as requested.

Regards to all the cool runners! ;)
T Aczel

One point I have never seen mentioned is how accurate are our mainly rebuilt gauges when we are comparing running temps? As most other gauges are not very accurate I can't see why the water ones should be any better. After all Steve's 180 may be the same as my 185 both on Bob west radiator cores.

Paul Dean

Paul, during my experimenting to try to sort out why my MGA was running hot, and how to devise a solution, I removed the temperature sender unit from the head and immersed it into an urn of boiling water for precisely that reason. My gauge proved to be surprisingly close to perfectly accurate.
And if the car was boiling over as I described above, it clearly was indeed running too hot any way.
T Aczel

I am trying to remember a conversation I had with Bob West and his mechanic James many years ago. I recall James saying that many of the modern replacement cores do not have the same thickness as the original (they are thinner) and the rows are staggered instead of in-line, e.g. only two rows of staggered tubes instead of the 3 in-line tubes in the MGA core. I might not have that totally correct, but that is what rings a bell in the back of my brain. I seem to remember James saying you can always check this out by pushing a small wire through the tank and measuring its length. The correct core thickness is 2 inches.

Steve Gyles

Paul, I checked my gauge with a digital cooking thermometer and it proved to be accurate within 1 degree.

I checked the digital one first in boiling water and yes I washed the probe after I checked the radiator as I didnt want to add an Bluecol AA antifreeze flavour in to the chicken!

I just realised that I have had an original MGA radiator lying on a shelf for 30 years in my garage, so have I had the "Holy Grail" of MGA cooling sitting under my nose for all that time?

Can I put it on a "no reserve" ebay auction and then retire on the proceeds?

Perhaps I will send you all a postcard from my newly acquired Caribbean island after it has sold! :-)

Or, more likely, it will turn out to be junk!

c firth

Thanks so much for the tutorial Mick! Very helpful. The MGA GURU site has a nice page on the "Cell Core" radiator as well - it is not mentioned as a "V Cell". Same radiator though.

Colyn - if and when when I sell my original radiator, I will purchase an island next to yours!

Referencing Steve's comment above about 2" being the correct thickness of the core. The black tie-wrap I'm holding against the MGA core is the thickness of the MGB core I was using - while a 1/4" might not seem like a lot of surface area it actually is when compared to the full height and width of the core.

Also, as Mick was saying, the fins on the MGB core weren't soldered to the tubes and could be slid up and down - very poor heat transfer.

However, I only see two tubes in each row on this original MGA radiator, not three. Or am I missing something?


(Still waiting on the radiator shop!)

Gene Gillam


You may well be right about the number of rows. I did say I was racking my brains to remember what I was told. I have to admit I get very confused about the construction of all this pipework, even after reading the above and Barney's ditties. I really need to go and cut one up to fully understand.

Steve Gyles

Gene - regarding your comment above, are you saying that the MGA initially came with a cell core radiator and the factory then replaced these with a tube-type radiator (later in production)?

So we reach the 100 post Mark ( a rare event here that shows the importance of this problem).

My gauge shows exactly 100C in boiling water. Zurich is at 500m, o that makes it pretty much spot on.

Old radiators that have been lying around for years are usually worth nothing as they corrode and leak terribly. So please pressure test before bidding on the Greek island....
dominic clancy

Ah well Dominic,
so its back to buying the National Lottery tickets then.

101 now!
c firth

Would the problem of getting more air flow through the radiator (at least when moving) be assisted by an acrylic lip installed at the top of the grill? These would be like the bonnet protectors that are available for new cars (at least here in Australia). I'm sure this would work, and am going to approach one of our manufacturers to see if developing one would be cost feasible. Clarke & Clarke in USA may also be interested in this.
Gary Lock

But why Gary, why?
It won't help at a standstill, and is unnecessary at speed (unless you're struggling with a crap core in the first place). Another unnecessary band aid?
T Aczel

Arrh, but Tom, going back to the start of this thread when Gene asked about extra cooling ideas because of air conditioning...I'm doing the same A/C project in my Coupe, and although it's not plumbed in yet, I'm getting prepared. I have the alloy radiator etc. etc., and running a 1950cc Oselli engine, so some extra air forced through when moving may help.
Gary Lock

Surely there must be some way of testing our individual radiators to measure exactly how much heat they are capable of exchanging?
If we could do this we would then be able to select one that actually does the job we want it to.

Imagine being able to just go out and buy an efficient radiator that we know will actually bring the temperature down to 175 degrees every time without having to do all this trial and error stuff.

Would it be so hard to do this?

Gary, in the meantime you could always try Neil Fergusons twin-fan set up like I did, it may be worth a try as an interim measure until you get your radiator to work as it is supposed to.

As I said earlier, I put them on to see if they would work well enough to replace the engine driven fan and to see if they would only be needed when the car was in stop/go traffic.
They seem to be achieving this and are off most of the time which frees up a little extra horsepower.

I also found that when they were left switched on by mistake, they brought the temp down to about 165 no matter even in ambient temps of over 100 degrees..
So they maybe could help with your running hot problem.

Your 1950cc Oselli has quite a lot more bhp than mine and so you should have enough to spare to power the fans even if they have to run for longer periods than mine do.

Why not ask Neil how his set up is working.

Hope you sort it out soon

c firth


Before you start anything else, add the inner fender louvers. That was a huge help in reducing cabin temperature and engine temperature.

Here's a link to my A/C installation if you haven't already read it:

Gene Gillam

Wow....Couldnt it be as simple as the crud that developes in the water passages at the back of the block? My car was filled with debree. I removed the drain plug and scraped out the passage with a peice of wire and kept at it week after week. eventually getting it all out.

Temp came way down after that. Its an 1800 3 main with everything else a bone stock A except for electronic ingnition and 3.9 pumpkin.

The other thing that helped a lot was jet hot coating the intake and exhaust manifolds. Im dumbfounded at how much heat can be removed from under the hood by just the jet hot coating alone. Huge difference in how the car performed in hot weather and traffic.

Would I do it again? Damn right I would.

This summer was a real hot one. After leaving a car show with my buddy Steve Mackay his car bean to overheat.He has a 1622 with T9 conversion stock radiator 3.9 rear end. He could go over 65 with out reaching boil over. My car was fine a little hotter than normal but not overheating.

He put the new product in and swears it helped.

I havent tried it yet but he swears his car is much cooler running now. Its not cheap but its suppose to last the life of the car with out causing rust.

Anyone else have any experience with this stuff?

Steven Devine


I'd heard various comments about it...some claim "snake oil", others, like your buddy, love it.

I am a fan of JetHot though...I really should have that done to my exhaust manifold.

Gene Gillam

+1 on Jet Hot. I looked seriously into doing the manifold myself with my home powder coating setup, and even bought some special high heat powder. Ultimately I concluded that the Jet Hot people would do a much better job than I ever could, and I have not been disappointed.

Also, IIRC there was some issue with compatibility with the high heat powder coat and the regular stuff... If the coating gun wasn't cleaned to absolute perfection after using it, subsequent coating jobs could be messed up according to what I read.

That said, my car isn't finished, so I can't speak as to temp reduction. My car never had any issues with overheating when I was driving it prior to disassembly, but vehicle overheating doesn't tend to be much of a problem in Alaska.

D Rawlins

Sorry Gene; we're really getting off the original question now, aren't we?
Here's my manifold jet coated; just got it back this week. A bit too much bling for my tastes, (I'd have chosen black or dark grey) but the choice of bright silver was made for me by my local cylinder head works who arranged the coating for me.
It will be interesting to see what it does to engine bay temperatures and the touch of fuel vaporisation I get after switching off and restarting in hot conditions.
(I'm currently building up an 18V engine to substitute for my 1622 chasing a bit more low end torque. Note the rod in the left of the picture, chamfered at the bottom end; all rods and pistons are now equal weight).

T Aczel

Hardly off topic since it's yet another way to reduce engine and engine compartment running temperatures! Looks really nice but make sure you chase the threads on the studs...don't remove them because you'll mess up the coating (experience, not guesswork...grin).

I have both the headers on my TC's Jet-Hot coated and love it.

Gene Gillam

Manifold, car and passenger all look great Gene!
I wish I could muster a similar level of enthusiasm from my own otherwise very understanding and indulgent wife!
Now my kids on the other hand..
T Aczel

oops, forgot to add the photo!

T Aczel

Okay...and the winning suggestion was from...I'll tell you at the end!

Got the radiator back from the shop - they were impressed with the new core - and I installed it in the MGA the next day (sorry, no photo). Bolted everything back up exactly as it had been before and took it out on the road for a test. I honestly couldn't tell a bit of difference - got just as hot and in just as short a time. I don't want to call it a waste of $422, which is what it cost me, but....

I was at my wit's end...wife actually said maybe we'll just have to drive slow if we wanted to use the radiator - NOT WHAT I WANTED TO HEAR!!!!

Got on the internet again and started reading everything I could about overheating and the main causes apparently, if not a bad radiator, were the water pump and the timing. Since I didn't have a water pump to stick in today I decided to check the timing. DLD had asked about it back on 6 Nov and I'd responded on 9 Nov with the following: "DLD, timing has been checked and rechecked...over and over. Dead on."

Well guess what hadn't been checked by me but by a mechanic friend I'd paid $200 to get the car ready for me to take on a trip to Florida...and guess what apparently "hadn't" been checked by him. It was severely retarded! I went out this morning, set it to 30 degrees BTDC and took the car for a drive. I was able to drive 70 mph without the A/C on with the temperature never going above 190, with the A/C on the temperature barely rose above 212 and that was running between 70 and 80 mph. I drove 20+ miles with the A/C on, then turned it off and drove back on the back roads - temperature dropped back to 190 degrees.

So...what can I say? I don't know whether or not I wasted $425 on a radiator but I do know I wasted $200 on what was basically a tune-up/oil change. I also know that from now on I'll always have time to do my own work and not trust it to someone else...lesson learned!
Gene Gillam

Gene, you are not seriously trying to say 30 BTDC static? That would be crazy. 30 to 33 BTDC at 3500 rpm with vacuum disconnected I would go along with. Can you elaborate?

Steve Gyles

Gene, so sorry to hear that you went through all of that with limited results - please rest assured that I gain no satisfaction in having mentioned the timing. I would imagine that you are gaining something with your new core. You at least have a nice clean system now!

So pleased that you will be AC ready when spring rolls will have one cool coupe!

Glad you are in good shape now!

As I wrote on 19th November

I suspect that many cars are overheating because they are a little lean or running with a little too advance, or both. A little adjustment on these can bring a big improvement on running temperature.

Normal static timing should be nowhere near 30BTDC. My engine is set up at 10BTDC static
dominic clancy

Steve, Dominic,

You took me too literally...I didn't think I needed to say I hooked up my setback timing light, disconnected the vacuum line, revved it up to 3200 rpm and set the timing to 30 BTDC...although that's exactly what I did. Better?
Gene Gillam

Gene..The last paragraph in your last but one post. " I also know that from now on I'll always have time to do my own work and not trust it to someone else...lesson learned!" A total truth !.
Neil Ferguson

Gene. Great, makes total sense now. Did you by any chance note the dynamic advance/static advance that had been set before you re-timed? Perhaps useful info for other 'overheaters'.

Steve Gyles


When I saw that the static timing was no where near the timing pointers at 1000 rpm I didn't bother to check to see what the actual reading was...I would guesstimate it was about 1-1/2" to the right of the first pointer. Funny thing is the car started and ran fine.

Gene Gillam

This thread was discussed between 25/10/2015 and 10/12/2015

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