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MG MGA - Running Too Cool?

Greetings All:

Just took my 1600 roadster out of winter storage and I'm puzzled. Historically, the temp gauge has read at or about 190 degF after warmup, but now I'm reading 140 - 160. I've got two cans of WaterWetter in there (because of past hot running), but even with this it's never operated below 190.

I know it's cooler outside (in the 70's) and that temp will climb when summer arrives, but 140 - 160 seems too low.

Do I have a problem?

Gary

Gary,
It sounds like your thermostat has failed in the open state. Also you may want to check your temperature gauge to make sure it's still accurate. It's surprising how many things can fail while sitting idle in storage.
Bill
Bill Boorse

Bill is probably right about the thermostat. They are cheap and easy, changing one is almost a diagnosis step. The infrared temp sensors are great for verifying the accuracy of the gauge. Whenever I see a reading on a temp or oil pressure gauge that raises questions I like to verify the accuracy of the gauge before going further.
R J Brown

I have the same issue - I cannot get above 120 in the winter unless I block off most of the radiator. With an ambient temp at the moment of 75F I am running at a steady 160F (70C), reaching 175 (80C) in traffic jams in town. This temperature behaviour is the envy of other MGA owners around here. The entire engine, head and cooling system is new and totally scale free, so this may have something to do with it.

If it takes forever to warm up, and never did before (and providing you have changed nothing over the winter), then it would imply that the thermostat has failed. It's always physically broken if it has failed, so easy to see when you take it out.

It's very unlikely to be the gauge.

A friend of mine last week sent me a picture that showed the source of his overheating problem. The entire top of the radiator and thermostat housing were gummed up with what looks like Vaseline which appears to be mildly corrosive (suggesting it is a surfeit of flux from when the new (Moss) radiator was soldered). (The head gasket was fine). Now we just need to figure out how to get rid of it all! If anyone is interested, dop me a note and I'll mail the picture.
dominic clancy

I would not be so quick to discount the guage. Even though my experience is that it tends to be an all or nothing deal, there may be something funny going on with the bulb. If you are going to remove the t-stat housing to check for open t-stat, I would also remove the bulb and dip it in a coffee cup of hot water from a kettle which has just boiled. The water will have cooled a little from the 212 but you should get a farily close reading if your stove and car are not too far apart. This is farily easy to do if you are going to be under there anyway.

Dennis, Az

P.S. Wish I could get mine to run at 140-160. I am using the racing sleeve and I still run at 190+!! It was higher with the t-stat. I also have the shroud which I have observed makes it run hotter!
Dennis

Thanks for all the good input. I'll replace the stat and see what happens. While I'm at it I'll check the temp. bulb response.

Dennis: Mine ran hot, too (over 200) so I added some "water wetter" and got an immediate 10 deg drop in operating temp!
Gary

Radio Shack sells an inexpensive infrared thermometer, I think it was under $30, handy to have around.
gary starr

http://www.radioshack.com/product/index.jsp?productId=2103171&cp=&pg=2&origkw=thermometer&kw=thermometer&parentPage=search

Derek Nicholson

Also check Harbor Freight, They have a web site too. Lots of cheap tools.
JEFF BECKER

This thread was discussed between 23/05/2006 and 24/05/2006

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