Under heating

[tom1985]

Hi folks, I've got a quick question I'm hoping you can help with. A couple of years back I fitted a water temp gauge, and generally the temperature seems to sit somewhere around 90C. However recently, it never seems to get anywhere near that. Is this anything to worry about? The only thing that obviously comes to mind is the thermostat being stuck open perhaps? Or is it just the cold weather?
The car is a 1098cc saloon by the way.
Thanks!

[oliver90owner]

Measure the real temperature. Thermometer, IR gun, anything. Temperature guages can go wrong.

A simple check is to feel the rad before the engine is up to normal running emperature - it should be cold if there is no coolant leaking past the thermostat.

Do you run it long enough? Heater full on will extend the warm-up period , as will cold weather, of course.

Effects of running too cool? Increased engine wear, poor fuel consumption, sludge developing in the engine, heater not working as well as it should. Need any more to convince you it is not a good idea to run zn engine too cool?

RAB

[tom1985]

Thanks RAB - i'll try that. Do you know what temp the engine should run at, when fully warmed up?

[oliver90owner]

It depends , to a degree, what thermostat is used. They should remain closed until they reach their stated temperature rating. As long as the engine does not overheat, all should be well.

The MM raditor is normally more than adequatly sized for the UK climate. Back 40 years, or so, a always ran my water pump and fan at a slower speed than standard, and never experienced any problems. That was with milldly tuned Ford engines - GT plus a bit.

RAB

[tom1985]

Apologies for digging up an old thread, but due to a house move I have only just got around to doing anything about this problem.

Anyway, I replaced the thermostat and that seems to have solved the problem. The engine reaches full operating temperature now, according to the gauge. As the engine was warming up, the top of the radiator remained cold, only heating up once the engine had warmed up. Hopefully this means that the new thermostat is doing its job, and the old one was indeed stuck.

For anyone doing this job for the first time, as I was, I found it relatively easy. I'd bought a new thermostat cover and studs, in case I needed them, but in the event the old ones came off without any problems. Don't forget, though, to buy the gasket that fits underneath the thermostat cover.