My 850 is give me a lot problem lately...
temp gauge is going to red (high temp) when I drive for more 30 minutes, when I do drive passed 30 minutes the cooling reserv overfilled by that time I have to stop and let the engine cool for about an hour, still after 10--15 it goes high again...

I just replace the thermstatic

Please help
thank you..


George of Boston

Before doing anything else I would replace the cap on the coolant reservoir. Get the cap from Volvo. Even a small crack or seal leak will allow the coolant to boil due to lack of pressure. Old caps can fatigue and not hold pressure. Don't assume the engine is damaged unless there is actual evidence of that. After replacing the cap fill the system to the proper level with the engine stone cold. Squeeze the radiator hoses to be sure the coolant has filled in everywhere and there is little or no air in the system. Start the engine up and observe it as it warms up - don't drive somewhere, watch it. Look for any loss of coolant or smell of coolant so you can see if there is a leak. Any leak will also lead to overheating due to loss of pressure at the leaking point, even if nothing else is wrong. Run the engine until the cooling fan cycles a few times, unless it overheats before then. If the engine starts to overheat without any loss of coolant then the radiator or some other part of the cooling system may be obstructed. If there is an obstruction you may feel the radiator hoses getting very hard.

George,

If the temperature gauge gets to red, that is bad news.

Yes, it is possible that nothing was permanently damaged, but it is also possible that you overheated your engine beyond its tolerance limits.

And the fact that it has happened repeatedly--bad news.

Have your car towed to a competent shop and have the problem corrected. Be prepared because they may tell you that they cannot correct the problem, 'cause your engine is beyond hope. If they are able to find and correct the problem, and they say that your engine is still viable, make sure that you have them do an oil change.

From now on, if you engine ever overheats, don't drive it 'till the problem is corrected. And, after it is corrected, watch the temperature gauge for the next week, to make sure that it actually was fixed.

Hopefully, it was short of RED! I really mean that. Water pump?