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MG MGA - overheating

As most know I've done a ground up restoration on my 58 MGA which also included a complete overhaul on the engine. Radiator was boiled out and pressure checked. In november of 2004 I drove the car 25 miles and the rear core plug blewout (7 psi cap). Fixed and drove another 30 miles but used a 4 psi cap, no problem. This is all cold weather driving.... Three weeks ago I drove 40 miles in 70 degree weather the engine gauge was steady at 190F. But, when I got home and parked (turned engine off) in garage the gauge started to climb to max and coolant spilled from the overflow. I tested the gauge and it was within 5 degrees on the plus side. Drove the car yesterday and the same occurred.. Will a 7 psi cap keep this from happening or should I look elsewhere??? I have a 60/40 coolant mix, water wetter, new thermostat, new hoses, 4 psi cap, felt pad glued to the hood above the radiator tank, new water pump and a oil cooler.. Have read the guru's web site but didn't find anything on my problem....
Mike
mike

Mike,
I'm no expert, but this is probably normal after the initial coolant fill up. Without an expansion coolant recovery tank, the overflow leakage will happen until the system has undergone its hottest cycle.

Upon shutdown there's a normal thermal "overshoot" as the coolant is no longer circulating, yet there is residual heat within the engine mass that must disipate.

Modern systems solve this with expansion recovery tanks and electric cooling fans independant of engine operation.
FWIW,
Doug
D Sjostrom

Mike
Engineers call this a hot soak. On shutting off the engine the coolant is no longer circulating and the temperature and hence the pressure in the top tank will rise, before it begins to cool off.
If you have the MGA rad topped off right up to the overflow pipe under the cap this pressure will blow off the cap and coolant will vent out the overflow. (They all do this,sir)
The only way to keep this from happening is not fill radiator right up to top or install an expansion tank

A couple of years ago I installed an expansion tank using an MGC brass recovery tank. I made up a bracket and attached the tank to the radiator support flange in front of the carbs. I then cut off the overflow tube at the neck leaving @2" stub, ran a hose from there to the tank and ran another hose from the tank's overflow back to the original rad overflow line that runs down and out alongside the rad. I fitted a 7lb MGB cap to the tank and a non releasing MGB cap to the rad.
Now I can fill the my MGA radiator right up to the overflow and when it gets hot it blows off into the recovery tank, when it cools it sucks the coolant back into the radiator.
It works great; I get a little more cooling and no more spilled coolant on the driveway for animals to poison themselves on.
John
John

I would use a 7 lb cap. This will raise your boiling point by 21 degree's. (3 degree's for every 1 lb on the cap)Make sure you have the correct cap. After you run your car, make sure you still have enought water in the radiatior and not neccessary to the top as stated before, it will be released by the overflow tube. You don't state what thermostat you have, I have to presume it is 190 degree and not a 160.As long as your water is holding after that first run and no more runs out and it stays about 1 to 2 inches from the top of the radiator all seems normal. As for your freeze plug that popped out, it was not seated properly and you should not have to worry about the others with a 7 pound cap.
JEFF BECKER

I am with Jeff your problem will become less by using a 7PSI cap. That said I have installed an expansion tank which does as it says on the box! Great modification.
Bob (robert)

Make sure you bleed all of the air out of the system. It tends to collect in the heater hoses. Any extra air will heat up and expand far more than liquid coolant. Keep us posted!
Steve Simmons

Mike

Is your radiator an original or recored to a modern standard - often the cause of overheating. Plenty on radiator cores in the archives.

Steve
Steve Gyles

Mike,

7lbs Cap works
Other than that what you describe is normal,I let the
coolant find its own level and just keep an eye on it.
You should just be able to see coolant at the bottom of
the filler neck.

Regards

David
David

I would go with David's suggestion about the coolant level. If it is just visible in the filler neck then it is correct level. Any more than that, then it will do as you describe.
Another thing I am curious about is the radiator cap you have. Is it the correct length? Moss sells the correct replacement radiator cap, Napa or others of the same sell a shorter version, causing the fluid to seep out when the engine gets up to temperature.


Ray
Ray Ammeter

I would think that a constant 190 deg is too hot. Have you checked the thermostat in a jug of water? -use the temp gauge in the car to see what it opens at. You should have a 72 deg thermostat - I tested 5 from Moss & found that they didn't open until 85 deg. I have found that the blanking sleeve works well on my 66 BGT that always used to over-heat in traffic on stinking hot days. it used to climb to 200 deg but now hardly ever gets to 180. Have also fitted it to 3 customer cars with the same result.
Garth.
Garth Bagnall

Garth, what's your normal running temp now? Those B-Series engines like to run hot.
Nick

Mike
I have tried all sorts of things to ensure my 59 MGA keeps cool. The initial overflowing you got is quite normal as already mentioned above.

Having tried an LBC fan shroud with little success,
I found the only way to keep it cool is to fit an electric fan. Kenlowe do a very neat one here in the UK c/w thermostat which I have not fitted (I use a manual switch under the dash) I have retained the standard engine fan to keep as standard looking as possible and a "summer" thermostat will keep things as cool as possible (normally 160 deg). When on, the electric fan plus the engine fan keeps the whole thing as cool as possible before shutting down the engine after a hot run. This should reduce the final temperature of the "hot soak", reducing the chance of hitting the boiling point at 7psi. When this happens a lot quickly comes out of that overflow !
Enjoy!
Pete
Pete Tipping

Pete

I still maintain that almost all MGA overheating problems come back to incorrectly restored/reproduction radiators. I run a 5-bearing 1800 engine and never have the temperature above 175 to 180 on a run.

A couple of years ago a colleague was having persistant overheating with his A. He had previously bought a new radiator. Whilst I had my engine out I lent him my original radiator - instant cure. He went back to our normal supplier, got an original spec radiator and has not had a problem since.

Steve
Steve Gyles

Hi Nick,
With a 72 deg t/stat it now stays on 160. I have had a much bigger rad core which only marginally improved the problem before fitting the sleeve. I cured a number of customers traffic o'heating woes by fitting the later GWP130 water pump & plastic fan. But wanted to keep mine lookimg original.
Garth Bagnall

Steve
I fitted a brand new radiator (made in China) so it looked nice and to improve the cooling - exactly the same... This leaked after a year and a day as they must! Took it to my local radiator guy. He could easily seal the badly soldered seam, but he noticed the inefficient "zig zag" fin construction which apparently only touch the water tubes at every fifth bend! So he rebuilt it with the correct MGA matrix still produced, with fine horizontal fins. Supposed to be five times more efficient. It was still the SAME !
I didn't want to, but that's why I finally succumbed to fitting the Kenlowe.

The temperature can exceed 200 hitting 100psi on the oil gauge too after switching off ! This being repeatable on two different gauges.

It really is weird this over heating. I have got my car to pretty well original, just the like the 1600 I owned from 1963-66. Back then I thrashed that car rotten, even beating a twin cam to the jazz club one night, but never a hint of overheating. That car would do 110mph with hood up and still accelerating, but red lined - great days before speed limits.

Is it this unleaded fuel doing it?
Pete
Pete Tipping

I've used the following radiator caps in my radiator and no overheating. I prefer to run at about 180-190, seems to run best at that temp. Stant 13358s 335 180; Parts Master 46004; Balkamp (NAPA) 703-1411. Marvin
Marv Stuart

Pete

I take my advice from Bob West and use his original spec radiators. Give him a call. 01997 703 828.

Steve
Steve Gyles

When you buy radiators from China, note that quality control is not always up to our standards. I had to spend an hour shaking out and picking out the long thin shards of solder out of the cooling tubes in the replacement BMW radiator my son had bought from a supposedly reputable american supplier. Had they been left in the radiator (and probably some were, impossible to do the job completely right without removing the tanks), I am sure his beemer would have had overheating problems too.

I have a feeling that what we consider to be "Moss" or "Vicky Brit" or .... problems are really every make's problems, at least to some extent, as more and more aftermarket parts for all sorts of cars arrive from countries only recently industrialized to a 20th Century level. FWIW
Bob Muenchausen

Both of my 1600's (roadster and coupe) have overheated from time to time (I have driven both of them for over 20 years). The only real cure is to ensure the radiators are 100% which I do by having them dismantled and cleaned every 2 or 3 years. Whilst this overcomes most of the overheating trouble, I think that the problem really stems from poor airflow through the grille. For example the big heater trunking up the front hardly picks up any air and the heater fan really has to be used to get any airflow into the car! When the factory raced them in the US they removed most of the slats and the Mk11's had an air dam type of grille to trap the airflow as does the MGB. I think that modern fuels probably have a bit to do with it too.
Barry Bahnisch

I have 1958 with the original radiator. I use a 180 degree thermostat and a blanking plate to block off the "warm up" hole in the head. The original thermostat had a sleeve that covered the hole when the temperature reached operating levels. Water then bypassed into the hole and passed thru the radiator. The hole aiided with warm-up but with new themostats, the hole remains open and some water bypasses the radiator. My car will get to around 200 degrees for brief moments when topping long hills in the summer. On the hottest days it will run around 180-190 degrees. I also straightened the vertical bars in the grill to maximize air passage.
Bill Haglan

Barry,
Most cars raced by the factory in the US did not have slats removed. Of the 11 cars the factory prepared and entered between '59 and '62 at Sebring (the only race they entered here), only the three cars entered in the '62 race had alternate slats removed from the grill and those cars used the early grill not the MKII type. Overheating was not a problem with any of these cars but it should be pointed out that they did run with a 1/2" wider cell core radiator than stock, no thermostat or fan blades and a blanking sleeve was fitted. The auxiliary air intakes either side of the grill ducted air to the carbs and under the bonnet, not through the radiator. The 1600 pushrod entries in '61 for example, were pulling 6700 rpm each lap and did that for 12 straight hours, so the cooling was more than adequate even with all of the grill slats in place.

Frank
Frank Graham

I have owned the same! MGA since 1968. When I first got it it was was bone stock with orginal engine/trans/rear end and radiator. I lived in hot sections of the US-Georgia and Kentucky. I ran hard and never got above 195 degrees. (I'm pretty sure the gauge was accurate.
I still have the orginal-restored- drive train, use a 180 thermostat and had to go to a repro (China) radiator some years ago. The old one just distintegrated. Now the car can run very hot. If I push it 75-85 mph on the expressway (or on track days at Road America) on a 90F degree day the gauge can top out at 220-225 plus.
I first began to notice this tendency to overheat when we all switched over to a % of ethanol in the fuel, then the fuel is also "oxygenated"-whatever that means. I think modern fuels do play a part.
I also have an oil cooler in front of the radiator-I'm sure that plays a part too.
A very good MG restorer I know asserts that as long as you have a good coolent mixture and good oil pressure, 230 degrees isnt going to hurt anything. I'll have to agree-at least in my case. I don't slow down just because its hot.
Tho' I am tempted to try Moss's re-introduced thermostat with the sleeve that blocks the coming- up -to- temp hole after the engine is warmed up.
John
jhays

Steve
So how thick is your Bob West radiator then - just checked mine with a vernier at 44mm (1-11/16") thick.

Interesting stuff Frank - could read that kind of info all day...

Pete
Pete Tipping

Pete

2 inches.

Steve
Steve Gyles

I stand corrected re grille slats but I guess my other points still stand. I wonder whether it was warm to hot on the race days in question as it is only on our very hot days (often over 100 Fahreheit here) that really finds them out. I was surprised at Silverstone some years ago when I took my 1600 roadster on a series of events in the UK to see that other UK A's often had electric fans fitted, not common here in Oz.
Barry Bahnisch

Mike,
When the engine overhaul was done did they boil out the engine block? I'm wondering if you have an issue with blockage or constriction of the water passages due to the build up of mineral deposits over the years. There is a thread in the archives about using muriatic acid and other types of acids to dissolve deposits in the the water jacket.
Frank
Frank Nocera

Steve

That is interesting - thank you very much...

Pete
Pete Tipping

Pete

Last time I spoke with James (Bob West's mechanic)he commented that a lot of reproduction radiators are a bit on the thin side and not efficient. The core should be 2 inches thick. I believe the pipe diameter is also an issue but I don't have any data to hand. I know the subject was discussed at great length last year and will be in the archives.

Obviously, I only have experience of my own car and that of my colleague. However, it is interesting that my car came back from the hot climate of LA as a basket case but with original equipment. I reused the radiator after a flush through and it ran fine. Also there was no evidence on the car of an electric fan having been fitted, nor was there any evidence of any bending of the slats. In short, I have NEVER had a cooling problem with the car either with the 1500 or 1800 engine. The old radiator finally sprang a leak about 3 years ago and that is when I got one of Bob's original spec radiators. It ran just like the old one, if anything slightly cooler rather than hotter. I only recently got round to fitting the horse hair radiator shroud in the bonnet (hood) and as far as I can ascertain it has not made the slightest bit of difference.

As an aside, last year I carried out the exact same expansion tank modification as described by John in the third reponse in this thread. I have not lost a drop of water since and still have a clean mushroom coloured carpet under the car!

Keep cool

Steve
Steve Gyles

Last summer I had this overheating problem, probably the threads mention by Steve, which I finally overcame with a new radiator.

The problem I had with overheating was severe. Always on the motorway and much worse on hitting any slight slope. As I mentioned then I did everything, slats, thermostat, timing, mixture, reverse flushing the radiator etc. All just sticking plaster.

The radiator I swapped to is a Moss Chinese made. The difference then and now is dramatic. Runs cool (@160 if my gauge is accurate) at any speed, the faster the better.

The gauge crept up once after a long run on a very hot day followed by a 30 minute crawl in traffic. I have fitted a fan for this rare, in the Uk, situation.

Chris.
Chris C

Sorry it took so long to get back with you all. But, with all the honey do's, graduations, birthdays, etc... I haven't had much time to drive the MGA. Who said retirement was easy? Anyway, I took the advice you all gave me and you where right on.. I drained and refilled the radiator with a 70/20 mixture and a half bottle of water wetter and filled the radiator until I could see the coolant in the filler neck (just below the cap stop indentation.). Put the 7 psi cap on.. Car still goes to 190F but doesn't overflow. Also, the temp. rises to 220F after shut-off but doesn't overflow. I'm satisfied.. I'm now thinking of purchasing a sleeve type thermostat that Moss has now.. Any thoughts on that??? Thanks again.. I'm closing in on the 500 mile break in. Have 320 miles..
Thanks again. Mike
mike

I'm confused. I thought you could use a blanking sleeve OR a thermostat, not both. Some of you are using both? Can someone clairify?
My new 1800 ran hot last weekend on the way to the Moss British Extraviganza with a newly re-cored "high-efficiency" core, shroud, manual and electric fans, 'B' expansion tank and Water Wetter. I pegged the gage at 230 going over The Grapevine (Big hot hill). The gage does read 8 to 10 degrees hot. I don't know how hot I got since the gage couldn't move any more. Scarey. I did not boil over. Three out of four "consultants" at the meet suggested removing the elictric fan (which I know did not have much effect at speed) since it blocks a lot of air especially behind the motor in the center of the fan. Took it off, and ran a little cooler comming home (with the heater on). I planned on tweeking the grille slats and removing the "summer" thermostat and installing a blanking sleeve. Can you / should you run both? Thanx Steve
Steve Meline

Steve, I run the blanking sleeve and a 190 degree thermostat in my 1600. Temp seems to stay about 195 here in South Carolina except when I go up the occasional steep hill.

There is another thread on this BB specifically about the blanking sleeve and thermostat. Barney Gaylord's web site has a great deal of information on this as well. It goes back the design of the original thermostat which had the sleeve incoporated. see http://mgaguru.com/

Like you, I have experienced overheating over the years. Now have the fan shroud, repo radiator, felt strip above radiator, oil cooler, and have opened the slats on the grill.

I remember driving over the Grapevine in the early 70s in my Mustang. It ran hot too.

I got my MGA not too far from you in Fountain Valley in 1973.

Good luck,
Don Carlberg
D. R. Carlberg

I run a blanking sleeve and a 160 thermostat. I did not quite hit 212 and I was behind you or ahead of you on the run!!!!. We both have the same set up and I still put out more heat due to the supercharger. You mentioned you have an MGA pump on and that may be the problem. Give me a call and I can help you. Time to go take my A out for a nice run today. Hope you all can do the same as it is only 85 degrees here today.
JEFF BECKER

Cheers Steve
Yes I have an oil cooler, fitted the 'summer' stat, radiator shroud and a fan shroud, played with the timing all made no noticeable difference. Will definitely think about Bob West's radiator type - perhaps when my newish rad gets a little bit older. Let's see what that Kenlowe can do on a hot summer's day in a jam this year...

Jeff, just you think yourself lucky with all that lovely sunshine - its chucking it done here! Wanted to go to Waddesdon too... MGA 50th anniversary and all.
Pete
Pete Tipping

The Moss "sleeved" T-stat is a work-around solution to the fact that the OE Smith's T-stats which incorporated one of these moving sleeves have not been made since the early 60s. Barney Gaylord's site, as mentioned, goes into some detail on this, and apparently, the Moss system does work as intended. So, there you have one option to take your cooling system's temp control back to OE standard.

Another, simpler, version of this same bypass shut-off mechanism is to use a blanking sleeve with your ordinary, over-the-counter T-stat, or with one of the "balanced" T-stats designed by Robershaw and now marketed by Prestone in most markets as their "Premium" T-stat. Yes, your warm up time may be increased slightly, but not enough for most of us to care or to cause any damage. My 68 BGT has used such a set up for years and comes up to temp within a mile or two.

I used this same setup on my 56 MGA with its tarted up 1950cc 18GA engine with no problems generally. However, since it produces more waste heat, I did have to use a plastic fan shroud (altho I would think a simple metal one around the fan itself a better solution today) and I did run a mixture of Redline Water Wetter/distilled water/Prestone pump lube in the cooling system and tweeked the grille slats on the repro grille back to angle more closely resembling that shown in factory photos of the cars. With all of that, I had very satisfactory luck with its cooling. FWIW
Bob Muenchausen

This thread was discussed between 06/05/2005 and 26/05/2005

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