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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - UNDERHEATING!

I converted my '66 1275 Sprite to a Vertical flow rad, because my original cross flow was on the way out. The V/flow was cheaper than a new C/flow, and I like the extra room and convenience of being able to remove my rad in less than 10 minutes including drain down. (v/flow bracketry modified for the purpose).

HOWEVER.

The bloody thing is TOO efficient!

I've got a 180 stat in there, and even in this relatively mild weather, I can't get the temp over 160F. Even accelerating uphill at 75mph, 2 up, and in 5th, the temp barely gets over 160f.

If I remove the fan blade, and run the engine stationary on fastish tickover, it eventually climbs to over 180f, and I can see the stat open as the gauges drops from 180 for a while, before beginning to climb and topping out at a little over 190f.

I tested the gauge by plunging the bulb into a boiling kettle full of water. 212F almost spot on. It's definitely the rad being too efficient.

It's a tripple row rad. The originals were only 2 row weren't they?

I remember some others having a similar problem to this, and discussing grill mufflers to reduce the airflow through the rad.

Does anyone have a picture of the best looking, and most convenient, and quickly fitted/removed solution?

I don't fancy a bit of cardboard or the like stuck on the outside of my grill.
Lawrence Slater

You could try some thick rubber roller door material fastened on with wing nuts. I used a similar method to waterproof a Classic Mini's distributor/coil and it works well. Should work as a good grill muffler and it'll come in a range of colours :D
J White

I thought the thermostat would self regulate ?

If the coolant is too cool then it would close a little...
Andy Phillips (frankenfrog)

Was the sender bulb previously located in the radiator or were you measuring temperature from the cylinder head tap? The gauge will read differently if the bulb is moved to the head from the downflow tank.

The thermostat is the ultimate governor of the engine temperature so I suggest replacing the unit and perhaps using a hotter thermostat for winter.

Only twice have I driven the midget in temperatures so low that the heater was able to take the engine temperature all the way down to cold. Driving was blow -10°F ambient temperature at highway speeds in both cases.
Glenn Mallory

I use an 89 deg (192F?) thermostat in the winter months. In fact the last few years I have kept that one AYR, I used to swap to an 82 for the summer. With an electric fan which rarely comes on it drives consistently at N on the gauge.
Guy W

Diito Guy - although mine is a crossflow rad. Ditch the mech fan and replace with electric for the few hours/days you may need it. A Mini one works fine on or make your own?
Jeremy Tickle

J White,
Who sells roller door material? I can only find complete cupboards and doors, and none made of rubber.

Andy,
The stat can't regulate if it isn't opening. The water ISN'T getting hot enough, that's the problem.

Glen,
Sender was, and still is in the head.

I mentioned hacking up hill at 75mph in 5th, and the temp didn't rise.

However, the opposite happens going down the other side. The temp dips below 160f, as the engine is making less heat. (A21 between Sevenoaks and Westerham exits. It's my favourite test track as there are no cameras).

Guy, I thought about using a hotter stat, but this is a 180f stat(82c). I've also tested it in water on the stove with a thermometer. It begins to open at a little under 180f. But only when the water reaches that temp of course.

And that's the problem. The RAD is keeping the water too cold, because it works too well. The top hose remains only warm. Only warm air coming from the heater. Contrast this to my C/flow rad(which had a leak but didn't over heat), which allowed the water to get far hotter, and the engine to run at 'normal' temperature.

The NEW V/flow rad, is effectively, TOO big.

Jeremy.
Nothing to do with the fan. At over say 30mph, the air is being rammed in, not sucked in by the fan.

As a test, I'm going to improvise some slot in slats to reduce airflow, and see what happens.








Lawrence Slater

Just wrap some tin foil round part of the front of the rad. I do the same with the oil cooler in winter.

Trev
Trevor Mason

CORRECTION.

I've been mixing up my crosses a verticals. I should have said I converted from a V flow to a CROSS flow.

And interestingly, back in the archives, I've found several threads, that show I'm not alone. And all were running 82c stats. Here's a couple.

"Temp in winter?" Posted 28 January 2012 at 15:56:37 UK time

"1275 - Over Cooling" Posted 23 March 2006 at 12:46:04 UK time.


I'm using the same stat I had when before I swapped to the CROSS flow radiator. Previously the temperature sat at around the 180 mark. So it is definitely the radiator that's made the difference.

But since the rad can't make a difference unless water is flowing through it, there MUST be, SOME water flowing in the rad, in order for the more efficient radiator to cool it.

I'm wondering, if during my 'stat test in hot water on the stove, I didn't quite spot when the 'stat began to open. If it opens even a small amount, that will allow water to circulate in the new more efficient rad, keeping the water temp down.

So maybe I'm partly wrong. Maybe I do need a hotter stat after all.

PS.
Hi Trev.
Yup, could do that, but I want a simple, easy, and VERY quick to apply/remove, solution. A flick of a switch type of fix. Not one that has to be fiddled with when needed.


Lawrence Slater

hugh kerr, Northern Ireland, United Kingdom

"My 1275 has been off the road for a couple of years for rebuild.

It now has a new radiator and a one-piece front (with 2 slats cut out along the back edge of the sides to keep underbonnet temperatures down).

There is a problem in that it now runs with high oil pressure and low engine temperature - probably due to the now-efficent rad and the extra air-flow.

I have replaced the thermostat (with another 82 deg one) but it is still the same.

I'm now considering blanking off a portion of the rad, semi-permanently, ...

Any other suggestions?

Thanks.

Hugh"

==================================================

And this just proves ONCE AGAIN. There isn't a problem you can have on these cars, that somebody else hasn't had before. EXACTLY the same problem. Better cooling resulting in the engine remaining too cold.

I almost wish now, that I'd bought a new VERTICAL flow rad(instead of an over efficient new x flow rad), and found a way to modify that for quick release. :- .
Lawrence Slater

Lawrence, If your stat isn't opening, then the water isn't being pumped through the rad and the rad isn't the culprit.

Fit a higher temp stat and the engine running temp will rise if the engine is working hard enough, and record higher on the gauge. Then when the temp does get hot enough for the new stat to open (190?) The rad will come into play to maintain this temp. If the rad is too efficient, temp will drop, stat will close and again, the rad is out of the equation.
Guy W

I have a vertical flow rad in a Frog with a 1275 engine and it runs very cool and takes ages to get hot. Initially it had no thermostat so I put the problems down to that although subsequently fitting one made little difference.
Temperature indicator tests ok.
Graeme Williams

Guys correct. The higher stat is the way to go Lawrence. Once I replaced mine with a higher temp one I got toasty tootsies instead of frost bite no problem. Don't bother changing back in the summer if your cooling system is clean. And I don't have an electric fan either.
Dave Squire

Lawrence
I can't get my head around this
The thermostat should control the running temp
The radiator itself isn't involved in cooling at all until the thermostat opens and allows coolant to flow through it
There must be circulation through the radiator apart from through the thermostat causing your problem
Are you sure that thermostat is fully closed off when cold and operating correctly -I'd pull it back out and make sure you can't see daylight through it and recheck it's opening temp with a thermometer in the pot
Are the heater hoses in the correct locations, you say you only have warm air coming out which can point towards an incorrect plumbing issue

willy

Engine bay pic showing the hoses ??
William Revit

You got me very confused at the start Lawrence with your mix up of rads!

Mine runs very cold too and that is a standard cheapo crossflow rad on a tuned engine. I only ever use it in the summer and even then on cool days it is around 70 deg C when on the move. I don't have an engine fan and I'm guessing it's a 82 stat. One thing I do have is a hole drilled in the stat to compensate for no by pass on the head. Maybe you have similar? Either way there is some by pass of the stat.

I don't think you have a problem other than a very efficient rad, I'd just blank it off a bit for now and see how you go in the summer. To blank my rad off on my old car I just cut some black foam up and slid it behind the grille in the middle. You can do it right across if required and then just take some out as the weather changes.
john payne

Think you're very brave, those running without a fan of any description, especially if any commuting is involved.
Lawrence, you're probably right about the ram effect above 30mph - surprisingly the readout on the 'modern' shows average speed at 28mph which includes weekly blasts up and down to Cumbria, so I wonder how much of the time we actually spend above 30?
I seem to remember reading somewhere (probably here) that the crossflow rad was originally fitted to export models going to hot countries and then standardised across the range by good old BL so it is probably too efficient for our wonderful climate - however with global warming...good anticipation Lawrence!
Jeremy Tickle

Its a common misconception that the rad sets the coolant temperature. It doesn't! The rad comes into play only when the thermostat is open and it is therefore the thermostat which controls the running temperature. They sent cars all over the world with effectively the same sized rad to run in different climates and very different ambient temperatures. The adjustment for different markets/ conditions was always based on which thermostat was fitted.

There is of course a degree of cooling directly of the engine block from air flowing through the engine bay. In cold conditions this could be excessive and mean that the engine never reaches the proper operating temperature, and in this instance one might want to restrict flow into the engine bay (via the rad) by use of a blind of some sort. But that air will be going straight through a cold rad anyway, if the thermostat is doing its job
Guy W

Hi Lawrence,

My '69 Midget also runs too cold even though it's got an 88degree thermostat. I was not surprised as years ago I ran a Farina A40 for some time without fan blades to solve a similar problem. Having said that, there were fewer instances of sitting in queuing traffic then.

I suspect a set of the grill covers as per picture would help. I have shown one side with the flap open. Being in two pieces each with a flap gives plenty of flexibility.




Ray Rowsell

I thought everyone partitioned off there rads in the winter...so im one of very few that do this...

Go figure

Lawerance you could paint the card board black and stick it behine the grill and secure with zip ties... I doublt anyone would notice

Cheap and easy...granted its still cardboard...just modified
Prop and the Blackhole Midget

I recall reading somewhere that the cross flow radiator was introduced due to insufficient space after an Air Pump[or some such] was introduced to comply with US pollution regulations. It was then introduced to all markets as part of standardisation.

On the other hand this may be all hot air!
Doug Plumb

I don't have my Sprite here to look at, so someone else can either confirm or deny my memory of it.

The heater tap comes off the head and the flow goes back to the radiator. Then, if you still have it, there is a bypass line between the pump and the head. These are each about 1/2 inch lines, so even with the stat closed, you have two 1/2 lines bypassing the stat assuming the heater tap is on.

That may well be enough to prevent reaching stat temp. Maybe you should blank off the bypass at the pump/head. Commonly when doing this, you drill a hole in the edge of the stat, but you get to pick a size, which I think is usually in the 1/8 inch range. Maybe doing so would limit the flow through the radiator and raise the temp.

Charley
C R Huff

I was wondering about the water routing for the complete system in Lawrence's case. My recollection is that the standard heater outlet is from the back of the head and flows through the heater core and is returned to the input of the pump via the rad hose so circulates in the head alone with the thermostat closed. The bypass hose does similar in allowing some water flow in the head with the thermostat closed which is returned to the pump inlet again. It would seem that something is allowing sufficient flow through the rad to over cool the engine which needs to be determined.
David Billington

Lawrence,

I do have the same problem. Like you I tried all kind of thermostats, measured temperatures on all different places in the motor with the infrared (ebola)thermometer. My winter solution since several years is this: see photo
Flip



Flip Brühl

Flip... its certianly not card board...haha
Prop and the Blackhole Midget

There has be an easier way to dry your laundry Flip.

:-)
Greybeard

" -- It would seem that something is allowing sufficient flow through the rad to over cool the engine which needs to be determined. ".

Hi Guy, David, -- ? Clearly, I need to repeat my earlier post. 11 January 2016 at 11:32:45

Self quote"
"I'm using the same stat I had when before I swapped to the CROSS flow radiator. Previously the temperature sat at around the 180 mark. So it is definitely the radiator that's made the difference. But since the rad can't make a difference unless water is flowing through it, there MUST be, SOME water flowing in the rad, in order for the more efficient radiator to cool it. I'm wondering, if during my 'stat test in hot water on the stove, I didn't quite spot when the 'stat began to open. If it opens even a small amount, that will allow water to circulate in the new more efficient rad, keeping the water temp down. So maybe I'm partly wrong. Maybe I do need a hotter stat after all."
End quote.
--------------

As you can see from the picture of my stat, it's not leaking, and doesn't have a bi-pass hole in it, as some do. When it's cold, it's closed. The only conclusion that makes sense then, is that the 180f(82c) is NOT the opening temperature, but the FULLY open temperature.

Although I tested it in hot water with a probe, I may well not have spotted the very first point when it BEGINS to open. ALL it needs to do is open SLIGHTLY, just enough to allow warter to circulate in the OVER EFFICIENT radiator, -- as compared to my previous radiator, which didn't shed heat as well, and hence allowed the water to reach the FULLY OPEN temperature of the stat.

So, either I get a HOTTER stat, or I REDUCE the efficiency of my radiator. And from what I've read elsewhere, and Flip has just confirmed, I need to reduce the efficiency of the Radiator.

Thanks Flip.
Well at least I know then, that even if I had stuck to a Vertical flow rad, I might still have had the same problem, since the new ones with extra rows ands capacity, are probably over efficient too.




Lawrence Slater

Well that's fair enough, but if you replace the correct rad with a 3 row one, then I don't understand why you are surprised that it is more efficient. But I still say, when water isn't circulating through the radiator, then it's efficiency is irrelevant. The engine operating temperature depends on the chosen thermostat and the physics of its operation.

What engine operating temperature are you aiming for?
Guy W

With more than 2/3rds of the radiator blanked off with stiff card, going up hill at 80mph in 5th gear, results in just below 180f on my gauge.

With BOTH cards tight together at the TOP of the radiator, the temp reached 190f.

The weather today is again pretty mild here in my part of kent. But it's predicted to become 'real winter', later this week.

So I'll leave it like that, and see what happens if we get -ve temps, and until the summer/warm warm weather arrives.

I'll eventually knock up some way of pulling a spring loaded curtain partially over the rad, by drawing on a cord or wire from the top of the valance, that can be done with only the need to open the bonnet. I don't think I need to have a control inside, because it's likely to be needed only twice a year.


Lawrence Slater

Lawrence,

Do you have access to a thermocouple thermometer. Maplin have some DVMs that come with a thermocouple for not a lot of money and you can then check the details of the crack open and fully open temperatures so it might give more information. I'd pop down with one or loan you one but you're in Kent and I'm in far off Wiltshire.
David Billington

Guy,

I'm NOT surprised it's more efficient. But I AM surprised, and a bit pissed off, that I'm having to fart around to get the water temp hot enough.

The temp I want, is between 170min and 185max. The engine runs well like that, is efficent, and looks after the oil.

Also of course, as I drive my Sprite all year round, I like to have a nice warm airflow coming out of the heater in the winter.
Lawrence Slater

I had use of a 1934 Rolls Royce many years ago. It didn't have a thermostat in the coolant circuit, but it did have a mechanical temp sensor which operated a series of levers and rods. These altered the angle of a series of slats in the rad cowling which varied the exposed surface of the rad core - an automated rad blind. Complex, but clever!
Guy W

Now that sounds BRILLIANT Guy. What a shame someone invented the wax stat, and caused the demise of all that.

Thanks David.
I wish you were closer, you seem to have an awful lot of useful gear. Nope, all I have is a cooking temp probe. AKA a thermometer that you stick in the water as you heat it. ;).
Lawrence Slater

Maybe I can find a minature venetian blind, and fit that.

And, as it happens, you CAN get them as small as 24cm wide.

http://www.directblinds.co.uk/venetian-blinds/micro-15-matt-white/
Lawrence Slater

Lawrence, One thing that I think is probably relevant is that the thermostat has a time delay in its responses. Particularly in closing down again.

So when it opens to allow water through to start cooling in the radiator, and the rad then does its expected job of dropping the temp, the 'stat doesn't snap shut again in water which is by then only a few degrees below its nominal operating temp. This would allow the water to continue cooling and you would get the situation that you have.

If you heat a 'stat up and watch it open it does open quite fast once the set temperature is attained. But closing down is a much less "snappy" operation; it dithers, moves in stutters and takes a good while to close properly.
Guy W

" -- closing down is a much less "snappy" operation; -- ".

Yup, you're right about that, although it did seem to be quite slow to open initially, until I could clearly see a gap (which is maybe why I didn't spot the temperature it was at, when it just opened). It also opens in the direction of flow. Maybe these deep impeller pumps -- mine's new -- also slow down the closing a little.
Lawrence Slater

I've also got an old adjustable 'stat. Albeit a lower temperature one.

I think I'll have a play with it, and see if I can raise it's opening temperature.

PS. You adjust it via a screw, which increases the spring tension.
Lawrence Slater

acording to Stant. http://www.stant.com/index.php/english/products/consumer-products/thermostats/faqs/

" ---- How does a thermostat work?

Usually located within a metal or plastic housing where the upper radiator hose connects to the engine, most of today’s thermostats utilize the "reverse poppet" design, which opens against the flow of the coolant. Thermostats have a wax filled copper housing or cup called a "heat motor" that pushes the thermostat open against spring pressure.

Within 3 or 4 degrees F. of the thermostat preset/rated temperature which is usually marked on the thermostat, the thermostat begins to unseat so coolant can start to circulate between the engine and radiator. It continues to open until engine cooling requirements are satisfied. It is fully open about 15-20 degrees above its rated temperature. If the temperature of the circulating coolant begins to drop, the wax element contracts, allowing spring tension to close the thermostat, thus decreasing coolant flow through the radiator. ---- "



That suggests, -- if it applies to all brands of 'stat --, that mine(AC Delco marked 82c) is opening WAY too early. And as others here have experienced the same problem, something doesn't add up according to the markings on the stat.
Lawrence Slater

<<Within 3 or 4 degrees F. of the thermostat preset/rated temperature>>

Ambiguous.Do they mean that is the level of accuracy? Does it mean that they are accurate to +/- 3 to 4 degrees, which is slightly different to saying it may start to open at 4 degrees BELOW its rated figure.

If the latter, then with your over-efficient radiator even with reduced circulation of a partially opened 'stat it could find an equilibrium with the engine generated heat that is below your desired temp. The solution is still surely to swap to a higher value thermostat so that this equilibrium is attained at a higher figure. It may still be below the 'stat rating but probably nearer to what you want.
Guy W

Yup, it does look that way on the face of it Guy. However, others have already tried 88c 'stats, and it hasn't fixed the problem. See Ray Rowsell

"My '69 Midget also runs too cold even though it's got an 88degree thermostat."

--------------
If this has always been the case with these 'stats, then the original radiators must have been designed to work with them to achieve the required engine operating temperature. Although I never had a particular problem in the UK with over heating, I did fit an electric fan for when I was driving in Spain/Italy/Greece etc, and sitting in traffic. And others have often reported over heating problems, with various schemes for venting the heat from the engine bay.

So the original radiators -- at least the original vertical flow radiators --, may well have been less efficient than they should have been. But it seems that the modern replacement radiators, not made to the original specification, are simply too good at dissipating heat, which does indeed suggest that a hotter stat is needed. But if the 'stat begins to open too far in advance of the final rating, then it's just guess work, to know what 'stat rating to go for.

I may need an even higher rated stat.

As it happens, I have an 88c 'stat in the Capri. I have to change a heater hose on that, so I'll pull the 'stat out at the same time, and bung it in my Sprite to see what happens. But I think even with a hotter 'stat, I'll still need to restrict the airflow through the radiator in the colder months.
Lawrence Slater

One of thse for accurate temp measuring -
http://www.amazon.co.uk/gp/product/B008730KXO?psc=1&redirect=true&ref_=oh_aui_detailpage_o05_s00
and one of these for adjusting the airflow through the rad - had one on my first car a Wolseley 1500, operated by a small metal chain from within the car, very posh (worked well until I forgot to check the temp gauge and there was steam pouring from under the bonnet!



Jeremy Tickle

FWIW - last year I bought a new vertical flow from Sussex Classic and it too results in my temperature gauge indicating some 10-20 degrees cooler. That said the sensor is in the radiator header tank and not the cylinder head - BUT - I too now seem to have only a lukewarm heater....

Simon
Simon Wood

Go on splash out and buy a new thermostat
Older thermostats,years ago used to fail hot, but the newer units seem to fail on the colder side opening too early which is a safer option I guess
Go on , get one
To me it's a bit wierd fitting a nice new rad and then blocking it's air off to cover up another fault
Got that thermostat yet--------

willy
William Revit

Willy, my 82 stat, is pretty new, and operates -- on the stove at least, as designed. The rad is too effective, that's the 'fault' if you can really call it that.

Simon. Mine's a sussex rad too. Very well made. Just too bloody good at shedding heat.

Jeremy, do you have any more detailed pics of that device? It looks pretty stright forward to make. Is the centre section a concertina or something? Does anyone still sell them? I reckon there would be a commercial market for something like that.
Lawrence Slater

The vinyl (and maybe earlier, leather?) radiator blinds were popular and even original specification on pre and immediate post war cars which didn't have thermostatic valve. At that time the means of controlling engine temperature WAS by control of the air flow through the rad. But it relied on the driver to keep an eye on temp and to adjust the blinds as needed. Its not an automatic system.

Then they began fitting thermostatic coolant valves to everyday cars to automate temperature control. Some people continued to buy and use the rad blinds, mainly as a means of increasing warm up time as they have significant effect on air flow around the engine bay, quite apart from, and before any cooling via the rad comes into play.

Continuing to try and control engine temperature by use of rad blinds is a very hit and miss approach. Taken to its logical extent you would need to be continually stopping to adjust the rad blind dependant on traffic conditions and whenever you had just reached the top of a long uphill haul, and were about to descend the other side!
Guy W

Jeremy. Lawrence. When I first got my then two year old Sprite in 1967 it had exactly that radiator blind fitted. It looked like it was a factory optional extra, because it looked so right.

The blind was a roller type, which was spring loaded and sat at the bottom in front of of the rad. To employ it, you pulled the chain in the cockpit which pulled the blind up to the desired height and secured it in a bracket on the side of the footwell.
When I crashed the car in '71, the blind was destroyed and I've never seen one since. Well, not until I just looked on Ebay. There are three.
http://www.ebay.co.uk/itm/Car-Radiator-Blind-New-Old-Stock-/311505857013?hash=item48873229f5:g:IkYAAOSw9N1VpNhg
Bernie Higginson

That looks pretty good Bernie. The trouble is, it's 20 inches wide, and the rad face where you'd fit it on a Spridget, is only 14.5/75 inches wide. Although, I suppose you may be able to fit it further forwards, where is widens out at angle towards the grill, as long as it doesn't foul the bonnet lock.

If it was cheaper, -- I may get one and alter it, but I doubt he'd accept a 25 quid offer, against a 68 quid asking price. A bit too cheeky methinks.

Looks quite easy to copy. Just have to buy some bits.
Lawrence Slater

Lawrence,
the picture was taken from here
http://www.anglia-models.co.uk/books-misc04-1.htm
about 3/4 of the way down the page maybe there was one for yor Consul too?
Bernie,
yours sounds exactly the same as the one I had; a metal chain (rather like those fitted to modern roller blinds) with a small metal ball at the end. IIRC it was fitted under the dash just below the Trico vacuum operated windscreen washer button!
Jeremy Tickle

That's a great link Jeremy. Cheers.

Actually I need to check the temp of the Capri, as although the temp reaches 'normal' the heater blows cool. I think the 'normal' on the gauge is misleading, and probably not accurate after 50 or so years. So I'm going to get a digi gauge to check it.
Lawrence Slater

Jeremy. Yes, that's it. The part of the chain that was inside the car was all made of little balls just like some modern house blinds except it was metal, so that you could slip it into the bracket to have the blind at different heights. I don't think I could fit one now because I have a Kenlowe fan which is in the place where the blind used to be.

That Ford site certainly brought back memories.
Bernie Higginson

I have exactly the same problem on my supercharged MGA. I have resolved it by fitting one of the radiator blinds that is mentioned below. I have tried various thermostats with no noticeable effects, and even with the heater valve completely closed it makes no difference. On a cold day with the radiator fully exposed to the air flow, the car struggles to maintain 50C coolant temp, bit as soon as the blind is closed up (from the driver's seat as described using short length of ball-type bathroom plug chain which is then connected at the bulkhead to a bicycle brake cable, which in turn is fixed to the to rail of the blind). The roller sits at the bottom of the radiator and is sprung so that when the chain is pulled the blind is pulled up to close off the radiator. It is easy to operate and I just set it at fully closed when starting and gradually lower it bit by bit until I get a stable operating temperature around 85C.

Pictures in the middle row here
http://clancy.ch/Accessories.html#grid

This underheating issue is not common on MGAs, most owners seem to have overheating problems that I put down to combinations of the following:
1. Wrong timing (too much advance)
2. Weak mixture
3. Coolant passages that are full of rust / calcium deposits
4. Radiators that are full of rust / calcium deposits
5. Radiator caps that are not holding pressure
6. Rubbish replacement radiators
7. Radiators that are "high performance" and restrict airflow too much in an attempt to compensate for 1-5 instead of addressing the underlying problem

Given the similarities between the two engines, I made sure that the Midget's coolant passages were good and clean and told the owner to put in a good quality new vertical flow radiator to original spec, set the timing with a little retardation from book for using unleaded and made sure the mixture was spot-on. It runs at 85C all day regardless of ambient temperature!
dominic clancy

Below is a pic of the shutters on my truck. They are operated by air pressure. They use what is called a shutterstat installed in the cooling system. The shutterstat operates an air valve to deliver or relieve pressure to the shutter operating cylinder.

On the left side of the radiator (rt side of pic) you can see some of the levers that operate it. Sorry about all the oil on the shutters. The oil cooler had just ruptured and filled the cooling system with the crankcase oil, which overflowed out the radiator cap.

Also, the 2-stroke Saabs had a manually operated radiator blind that was like the rolled spring loaded window blinds, and it was operated from the cabin with a knob attached to a pull chain.

Charley


C R Huff

I hate to raise this issue but are you sure that the temperature gauge is reading correctly (I looked in other comments above to see if anyone had mentioned this - apologies if I'm just repeating something). I had a chronic overheating problem last year and replaced my rad with a three core one. I was shocked afterwards to find that it ran very cool - or so the gauge indicated. After checking everything else I changed the gauge and - hey presto - normal temp was resumed. I figured the overheating had b*****ed up the old gauge. Just a thought.
Chris Hasluck

Like the truck Charley.

And I'd forgotten about the Saab 2 strokes. Just back from a stroll down Memory Lane!
Greybeard

"I hate to raise this issue but are you sure that the temperature gauge is reading correctly --- "

Hi Chris. From my first post in this thread.

"I tested the gauge by plunging the bulb into a boiling kettle full of water. 212F almost spot on. It's definitely the rad being too efficient."

Plus the heater temp is cool, to warm at best, unless I block the rad, and then the gauge responds positively in turn.
Lawrence Slater

Just letting you know, if anyone is interested in the roller blinds for sale on Ebay, that Bernie linked to.

The seller, doesn't like people asking questions.

I had the temerity to ask if there were any instructions with the kit. The reason I asked, was because there are numerous items in the kit, and it's not immediately obvious what they all do (to me anyway). I thought it would be useful if there were instructions, and asked if there were any, because often sellers forget to include things like this in their description.

His reply was. -- "Best you carry on and respectfully stop wasting my time asking questions. "

If he thinks asking questions is a waste of time, I wouldn't be too keen to buy anything from him.

How many do you think he'll sell for 68 quid? I don't reckon it's worth that at all, esp for a Spridget, as it's too wide.

Shame he has a bad attitude though, as I may have given him 40 quid to save on some time making my own. Now I'll just copy that.

Simple enough, here's the picture.




Lawrence Slater

"Best you carry on and respectfully stop wasting my time asking questions. "
How unbelievably rude! And stupid, who'd buy anything from such a t#sser. Best avoided and thanks for the heads up.
BTW don't buy from KD Sheds 2002 in Brum; good sheds but unbelievably bad attitude to customers. Avoid.
Jeremy Tickle

Charley. How does the shutter stat work on your Truck?

That would be a neat solution, if the I could add shutters that only close, say below 15c.

Totally over kill of course, but such a gadget appeals to me.

Where could I get a shutterstat, in the UK?
Lawrence Slater

ACTIVE SHUTTER GRILLE VENTING.

"Over the past few years, more automakers than ever have started to promote something called active shutter grille vents.

Essentially a way to boost fuel economy at higher speeds, active grill shutters are now being used by GM, Ford, and Chrysler--among others--to give gas mileage boosts to their highest-efficiency models -- "

http://www.greencarreports.com/news/1079678_active-shutter-grille-vents-how-they-help-improve-mpg
Lawrence Slater

It's NOT only waterflow control, that's important or the most significant factor in cooling and controlling the temperature of the engine.

"Before the development of viscous-drive and electric fans, engines were fitted with simple fixed fans that drew air through the radiator at all times. Vehicles whose design required the installation of a large radiator to cope with heavy work at high temperatures, such as commercial vehicles and tractors would often run cool in cold weather under light loads, even with the presence of a thermostat, as the large radiator and fixed fan caused a rapid and significant drop in coolant temperature as soon as the thermostat opened. This problem can be solved by fitting a radiator blind to the radiator which can be adjusted to partially or fully block the airflow through the radiator. At its simplest the blind is a roll of material such as canvas or rubber that is unfurled along the length of the radiator to cover the desired portion. Some older vehicles, like the World War I-era S.E.5 and SPAD S.XIII single-engined fighters, have a series of shutters that can be adjusted from the driver's or pilot's seat to provide a degree of control. Some modern cars have a series of shutters that are automatically opened and closed by the engine control unit to provide a balance of cooling and aerodynamics as needed."

http://en.wikipedia.org/wiki/Radiator_%28engine_cooling%29

As I argued, and others discovered before me, the radiator can be too efficient, irrespective of the thermostat employed. I need shuuters or some other means to reduce airflow in cold weather.
Lawrence Slater

On the racer, unless it was a particularly warm day, I would add tape to the oil cooler and the bottom of the radiator to reduce cooling.

It did run with a blanking sleeve rather thn a 'stat, though.

In this pic, you can see that the tape on the radiator is falling off!


Dave O'Neill 2

Lawrence,

Here's what you need - 'optional extra' for the Ford Anglia in it's day!

All controlled from the comfort of the 'facia panel'.

Ford Part No. 105E-18690 - just pop in to your nearest Ford dealer and pick one up??

Richard


Richard Wale

Lawrence,

There's even something very similar to the Anglia one on eBay at the moment for £68 incl. P & P or offer.

eBay auction 311505857013.

If you really want to push the boat out, there is also one 'made-to-measure' for a Ferrari for £2,750!

Richard

Oops, should have read ALL of this post - it's already been covered.
Richard Wale

I'm going to make my own Richard. Should be easy enough.
Lawrence Slater

Lawrence,

The shutterstat is not dependent on ambient temp. It is dependent on coolant temp. It screws into the water jacket and opens or closes an air valve dependent on coolant temp.

So, for it to work, you would have to have a source of air pressure on the car. Trucks have lots of air operated equipment, so they have compressors. I suppose it could be operated on vacuum, but shutterstat technology is pretty old now, so I don't know how hard it is to get them anymore. They kind of got left behind when fan clutches or electric fans became the norm.

Thanks, Greybeard, it's hard not to like the old truck. It's a 66, but the design goes back earlier. Autocar was one of the last trucks to have a butterfly hood and the real radiator out front (instead of a shell). When driving in slow traffic in the rain, steam rolls off the cast aluminum radiator tanks.

Dig the cool mudflaps.

Charley


C R Huff

Thanks Charley.

-------

Earlier, I remarked that I had an 88 deg c 'stat in my Capri. Yesterday I whipped off the housing to take it out and shove it in my Sprite for a test. But to my surprise, it was an 82c 'stat.

So where is my 88c 'stat?

Also yesterday, I took the RWA Midget out for a spin, for the first time since it's actually become winter with a -ve degree temperature. I could barely get the temperature gauge to read over 140f. I took the 'stat housing off, and what's in there? My 88c (190f) 'stat.

So that's two cars both with x-flow rads, that are keeping the engines too cold, and one has a 190f 'stat. But, the Midget is even colder.

I held the 'stat to the light, and disvovered that it doesn't fully close. It's got a designed/manufactured bi-pass built into it. I assume this is for the same reason some have a 'jiggle' pin/valve, to allow trapped air to escape.

I put it in hot water with my temp probe, and heated it up to boiling. It doesn't start to open until it reaches over 175, but in the car, the gauge didn't get even close to that. The manufactured gap is very small, but clearly it's enough to allow sufficient flow, that in very cold weather, the water simply can't get hot.

I'm going to see if I can hammer this hole closed, and see if that helps. It must improve the situation, but I suspect I'll still need to reduce the airflow through the radiator -- ON BOTH CARS, to get the engine temp right in decently cold weather.

I only bought this 'stat recently. Are they all made like this now? This one is unbranded. Who makes/sells a decent branded 'stat, to original spec, that DOESN'T have a 'jiggle' pin/valve, or a hole in it?


Lawrence Slater

It's hard to believe, BUT ---

I gently hammered that gap closed, and shoved the 'stat back in the Midget, and went for a drive in very close to -ve temperatures. The result is, a steady 170f reading on the gauge.

That very small gap, was sufficient to allow just enough water flow, to keep the gauge reading 140f. It's a 190f 'stat, so it should still read higher, but 170f is a lot better than 140f.

Whilst draining and filling my Midget, I noticed that it has a TWO row radiator. I guess it could be the original, or at least the original spec. Still 'overcools' the engine, but not as much as the THREE row rad in my Sprite.

Anyway, I've now swapped the same 190f 'stat into my Sprite. When I get a chance tomorrow, I'll see if it makes as much difference as it did in my Midget.
Lawrence Slater

Lawrence,

You found it! congratulations. If the thermostat is hermetically closed how can warm water reach the thermostat?

Flip

PS I had a floating valve in the thermostats. It blocked the thermostat. So I took it away. Now I use the towel. Next time that I take it apart I will close the hole.


Flip Brühl

Flip,

I would say that if the head has a bypass hose then there will be flow around the head to keep water flowing past the thermostat so when the water is hot enough the thermostat will open and water will then circulate through the radiator. I don't know about the later non bypass hose arrangement. The bypass hose equipped water pump puts coolant into the water jacket around the cylinders which then makes its way into the head and back towards the the thermostat/ bypass hose and back into the pump inlet, when the thermostat opens water will then flow through the radiator and back into the water pump inlet to repeat the cycle.
David Billington

That's some blockage Flip. Is that a new 'stat? What brand? How can they make such crap, that the valve can float over and jam the 'stat open?

As I asked earlier. -- Who sells the original spec, originally quality 'stats, made without any kind of bi-pass mechanism in them?
Lawrence Slater

This thread was discussed between 10/01/2016 and 19/01/2016

MG Midget and Sprite Technical index

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