Mondeo overheating

[jimcognito]

Hi. Have recently got myself a 1998 mondeo 2.0 6v zetec. I noticed it had a slow water leak from the thermostate housing. It also required a new rad, as the old one had split at the top. I replaced the rad and will be sorting out the other leak very shortly. The problem is that after replacing the rad, the car over-heated very quickly, far quicker than with the damaged rad. I have very limited knowlege of fixing cars but i would hazzard a guess that this is due to that fact that now the radiator doesn't leak, there's nowhere for the pressure to release? So my question really is: Could it be the thermostat housing (or a part inside it) that is causing the overheating and maybe stopping the circulation? I also noticed that when i loosened the lid of the filler cap, it bubbled away frantically like a witches cauldron which led me to thinking that, for that much air to bubble, the water isn't circulating properly (if at all). I do realise that this could be the water pump but don't want to jump to too many conclusions as my brain is now hurting Any advice welcomed.

 

[Burnerman]

Try running the engine without the thermostat...if it boils again you could well be looking at cylinder head gasket problems.
A garage will be able to do a coolant 'sniff' test for you - they put a probe in the air above the coolant in the expansion bottle, and if products of combustion are present, the liquid present in the probe changes colour.
John

 

[^neo^]

I'd make sure it hasn't got an air lock if it was ok before the rad change

 

[jimcognito]

Ermmm.........and how would i remove an air lock? i just assumed that any air in the system would work it's way out as the water is pumped around.

 

[jimcognito]

I have now replaced the thermostat, and still no joy. The car still has a small leak on the thermostat housing which i will get around to replacing soon (if it's gonna be worth it). What leads me to think it may be the head gasket is i am getting a hell of a large amount of air coming into the cooling system and it does smell of engine fumes. I have checked the oil and see no signs of water on the dipstick or the filler cap, all clean and good there and not a spot of mayonaise to be seen. My 2nd question is: if it does require a gasket replacement, considering the age of the car and the value (around £500) is it worth throwing money at it or should i send her to the breakers and cut my losses?

 

[Burnerman]

The sniff test will ascertain if the head gasket has gone or not.....after that its really up to you what to do.
If the car is in generally good condition, a repair could give you a few more years of reliable motoring. If its not, then its best to let it go.
John