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MG MGB Technical - Overheating 205deg F ??

Got caught in a bit of traffic the other day after an extended drive in very hot weather and the temperature really started climbing. Normally sits on around 180deg up and down a bit, and have been in traffic before without too much drama, but have never seen the temp climb that high. I was in the city as well in a parking station and it was impossible to pull over anywhere. I wont ever get myself in that situation again but at what temp should you be starting to hit the panic button? I have seen before on these boards that temp can quite happily go to about 220 because the system is pressurised.In all the time I have had my MG in tropical Queensland, I have always cast a wary eye on the temp guage as I have had minis and other British cars before which are prone to overheat out here in traffic.
Mine was starting to run a bit rough at 210 so I wouldn't like to go any higher.
Is there any cool down procedure you should go through before turning the engine off?

There was no ill effects (I don't think !) luckilly as I have just had the engine rebuilt.

Would appreciate any advice
Craig Williams

Craig. Here in Arizona, the cars tend to run rather hot in the summer. On my 68 GT, the temperature gauge is regularly at the 3/4 point and almost goes to the max point when stuck in traffic. Flushing of the radiator, new hoses, new pressure cap and a 25% AF-75% demineralized water set up seem to keep things within acceptable limits. I am going to be doing some more experimentation this summer and will write up my test results. (Purchased an infa-red thermometer which allows me to take actual readings of the cylinder head, hoses and all of the radiator and am going to have a spare radiator re-cored with a Modine core to see what changes this will make in how hot the car gets.) In the mean time, the use of an oil cooler, if you do not have one, and an electric fan to supplement the engine driven fan, might be worth considering. What I can tell you for sure is that, after many years as a daily driver, my car is still starting and running fine in spite of the elevated temperatures the engine has been subjected to. Hence, I would not worry a great deal about what you are experiencing. Les
Les Bengtson

Thanks for your advice !

What do you think about shutting down when the engine is that hot ? Is there any preferred method. Not much you can do I suppose, if you leave it idling it will just get hotter. What is the time to pull the pin do you think. I worry about my car because it has had a couple of rebores and I guess ??? it weakens the walls, makes it more prone to cracked blocks etc. What do you think. What is the safest temperature you can operate at ?

Craig

Craig,

After years of fighting stop and go overheating, I installed a 165 thermostat. Eventually, an overheating car will do just that, but approaching the stop and go traffic, I'm running ten to fifteen degrees cooler. Sorta like extra insurance. The flip side is, once running again the car will cool to 175 or so. FWIW the 165 thermostat is the standard thermostat for the 18G/GA three main engines. I have a 180 themo installed now for the winter months=cabin heat!

My experience with "pulling the pin" has been two prong. Stop and go overheat, I've let it peg and gently got it going again--no hard acceleration. On open highway driving I've shut it down at 215, opened the bonnet and let it cool for a half hour or so. I did the later coast to coast (3,200 miles) in 95 degree, humid weather. It took a while longer, but I got home intact. Car seemed to run coolest at 45/50 mph.

Good luck,

Paul
Paul Hanley

Craig,
I had similar problems when I first got my B.

A radiator re-core and a 165f thermostat later, and I have not seen temperatures over 200f since. It got to 195f just once on a run up the range to the Darling Downs on a "really" hot day. That includes being stuck in traffic on an equally hot day for about 20 minutes.

so.. have you had your radiator checked?


P R Akers

Craig,

Couple of products around that may be useful

Redline Water Wetter
http://www.redlineoil.com/redlineoil/wwti.htm

http://www.evanscooling.com/main21.htm

Also a product called For Life which has a boiling point of 180deg

I would also use electric fans as if you do shut engine off you can at least keep these working to cool water.

Also oil cooler or larger oil cooler will help keep temps down and larger Ali rad.

Paul
Paul Wiley

The book says as long as it doesn't reach the H zone or start losing water it is OK. However the important thing is that if it has only started doing that recently in similar conditions then something has changed which needs looking at. I submit that making modifications to overcome such a situation is only covering up the real problem, which may suddenly get worse and strand you. On a numbered gauge I would treat the H zone as the bit around the highest number, mine are CNH gauges but from Clausager this looks to be about your 220. My V8 reached the red once but apart from running a bit rough there was nothing else untoward. If you have electric fans leaving these on having switched off the engine, particularly if you open the bonnet, gets rid of a huge amount of heat in just a few minutes.
Paul Hunt

Craig, I fought this type of problem in
Southern California for a while also.
As others point out, the solution is to get
a recored radiator -- check the archives for
pros and cons of adding more rows, aluminum vs.
copper, etc.

A UK company called Powerstop sells an aluminum
radiator as one option. But a local shop should
be able to source a better core with more fins
and larger tubes. The stock radiator was really
designed for milder climates and is just not
up to the job.
Ronald

A spray bottle with water, sprayed into the cooling fins of the radiator while idling can help bring down the temp a bit before shutting down. Just remember that once you shut down, the temperature is going to climb back a bit, because circulation has stopped. Don't spray directly onto the engine. This assumes that there is the correct amount of water in the system--a dry or nearly so radiator doesn't transfer much heat. Another thought on cooling: after many years of service, the impeller on the water pump can erode, losing efficiency. How old is your's?
R. L Carleen

210 isn't bad, newer engines have the cooling fans kick on at 220. Higher temps = more HP, except of course the fuel/intake manifold should be cooler. Actually it's not that the engine suffers at elevated temps what is the problem is that hot pockets develope and the water based a/f boils off at those points and uneven cooling takes place, especially in the head, which leads to warping. I have seen engines run at 280* using non-water based coolants with no problems as the a/f does not boil off and create hot spots. Check out Evans Cooling:

http://www.evanscooling.com/index2.html

The engine is running rough as the engine wasn't tuned to run at those elevated temps. Nothing I'm sure was hurt.

One of the great mysteries to me is why the MG factory never used fan shrouds which can greatly increase air flow through the rad at low rpms such as being stuck in traffic. If somehow you can fabricate a shroud I think that would help a great deal.
Mike MaGee

Moss has shrouds for both the A and B.

FWIW

Larry
Larry Hallanger

A quick method of cooling is to turn on your heater and defroster. This sounds crazy on a hot summer day but the additional flow through the heating system brings the temperature down to an acceptable level. I might personally get hot but better me than a fried engine.
Lee Sheldon

Larry. My Moss catalog only shows the shroud for the Mark I cars. I would be more than willing to fit a shroud to my 68 as it is a daily driver. If you have a part number for other than the 62-68 cars, please post it or let me know. Thanks, Les
Les Bengtson

This thread was discussed between 14/12/2003 and 16/12/2003

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