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MG MGB Technical - Now why is this? (getting too hot)

Spend my day in my garage, final test drive had the result, that coolant was sputtering out of the radiator (that tiny hose under the cap) and, the engine smelled and felt overly hot, especially around the head.
Changing the thermostat housing reusing the old thermostat and installing an aluminum valve cover are unlikely culprits, but I also changed oil & filter, with enough in the sump (triple checked) and good pressure (MANN filter with anti-drain, btw).
Being used to having the HT wires marked, I unplugged them for changing the filter, finding myself tracking down the first cylinder later, by checking which cable is fed by the rotor with the timing mark at the correct pointer, then turning anti-clockwise in firing sequence. This resulted in the engine firing up straight away with the same idle revs as before, so I'm rather sure I'm right...
Any ideas??

Jochen
Jochen Beyer

you don't think you put the thermostat in upside down do you? RIC
Ric

Jochen. Check the thermostat to make sure it is in correctly as per Ric. While doing so, check it out in a pan of water to make sure it is really opening as it should and at the temperature it should. These things operate correctly so often that we get out of the habit of checking before installing. There are a few bad ones out there.

I find that, when I drain and refill the cooling system, the first "topping up" of the system is not enough. I run the car for five minutes or so with the pressure cap loose, then allow the engine to cool and add more coolant mixture. I always seem to need to add at least a quart more than the initial filling.

Spilled oil or coolant, which got on the engine, may give off the heated smell you mention. You should be able to use a thermometer in the filler neck to see what the actual operating temperature is. Run the engine up to operating temp with the pressure cap loose, then remove it carefully and stick a thermometer into the coolant to see what the actual operating temperature is. It may be a bad headgasket that decided to go our while you were working on the car or just before you worked on the car. There is a concept called the "ad post hoc fallacy" meaning that what has just been done did not, necessarily, cause what happened immediately after. Thus, your problem could be unrelated to the work you performed. But, do check out the thermostat and make sure the coolant level is adequate. Les
Les Bengtson

Just a thought, but was your temperature gauge telling you that the car was hot? If not it could simply be the radiator finding its level after refilling.
Steve Postins

Thermostat is in the right way and gauge reads "N".
Sleeping over the problem I think I know now:
I also removed the heater tube across the valve cover and it was empty, and afterwards I didn't open the heater valve, so there's probably too much air in the cooling circuit, allthough the radiator was full.
I'll check and give you the results later.

BTW, thanks for your help, having been MG-less and thus MG-related-questions-less for nearly two years, this board still proves to be the one source of information to rely on.

Jochen
Jochen Beyer

A simple thought: do you change thermostats with the season?

I had one that just went bad -- up to 180* driving, spitting out when stopped -- latent heat up to 212*.
they are cheap to replace.

Hope its's an air lock though.
glg

A fail safe thermostat is cheap insurance.
David

This thread was discussed between 30/05/2003 and 31/05/2003

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