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MG MGA - 205 degrees, always, all the time

Here is a question for those far more knowledgeable and experienced than I...

I know there have been many threads on overheating but none quite like my situation. I bought my MGA last October. The PO swore that after owning the car many years he had hit on the perfect combination of parts that prevented overheating...since the car lived for 18 years in Sacramento CA (a hot dry climate) I was inclined to believe him. He replaced the fan with a five-blade plastic fan and used a Stant 6 radiator cap. Standard 1600 MkII oil cooler. NO felt seal, no water wetter, no electric accessory fan. Interestingly the car starts up and within minutes hits 205 degrees on the temp gauge. Then it stays there, seemingly frozen, never climbing upwards even in the most severe heat (last week 107 degrees and humid, stop and go driving), or after extended highway driving in hot hilly areas. The gauge might drop down to 190 when coasting down a hill with cool outside air, but that's the only time I ever see it drop.

I *might* have an inaccurate gauge. But after owning the car for seven months and discovering PLAIN WATER in the radiator, and switching to a mixture of coolant and water made no difference to engine temp at all...

Last month I had a valve job because one of them was stuck. Mechanic said it looked like intense heat at some time in the past...related?

To top it all off, the car runs spectacularly well! No sputtering, timing issues or vapor lock. No run-on after turning off ignition. A *little* clattering from the valves that need the gap adjusted every couple thousand miles, but isn't that normal?
Jim Paul

Hi Jim. Valves usually stick in the valve guides due to insufficient clearance. Lack of clearance can have several causes. Lack of proper lubrication can cause metal burrs to form, seizing the valve. Excessive oil consumption can build up carbon inside the guide, seizing the valve. Improper (reamed) clearances (especially on bronze valve guides) can cause a valve to seize. I once had a valve seize for no apparent reason. The engine had been running very well, and had NEVER overheated, and had seldom exceeded 200 degrees on the guage. Since your guage NEVER moves past 205 degrees, it is quite possible that the guage is stuck. I would remove the guage, and place the temperature bulb in a pot of water. Heat the water, and watch the guage. When the water boils, the guage shoud read 212 degrees. If it reads only 205 degrees, then the guage is stuck, and should be repaired or replaced. If your engine ever did overheat, and the guage WAS stuck, you could (perhaps) do serious damage to your engine without even knowing it was overheating! And yes, some noise from the valves is quite normal. A light clattering is what you should hear. Cheers! GLenn
Glenn

Paul
I live about 60 miles south of Sacto. I had the radiator rebuilt with a heavy duty core using dimppled water tubes,the same as used on diesel trucks and a 190 degree thermostat. I used a plastic fan only because the metal one lost a blade at 65 mph. That was about the time I had the raditor rebuilt. The car always runs at 190 except on the hotest days, over 100 degress. I would check your guage first then go to the radiator.
Bob
Bob Swain

Jim, get it fixed quick as Labor Day is almost here and another run in the Santa Moncia mountians. Hope to see you there
JEFF BECKER

Heh! Labor Day? News to me...I'll be there. Just came home from a 3-hour night drive down PCH, up Decker Canyon and Mulholland through the mountains. Spectacular warm night here in LA, not many evenings when you can drive at night in a t-shirt...usually too cold. City lights and stars were amazing. Car ran great...
Jim Paul

This thread was discussed between 26/08/2005 and 27/08/2005

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