Blown HEad Gasket or is it a bad temp sensor?
 

New to this forum. Problem is with my dad's '94 Concourse D'Elegance with the Northstar. Just over 200k miles. This is in order of sympton and what has been done.

Coolant level low. Noticed seepage by radiator head. Had Cadillac dealer replace radiator.

Climbed the local mountain in Ca from Clear Lake to Santa Rosa, boiled over just as cresting grade. Back to dealer. Said it was a thermostat. Check flow and it was perfect, so they say water pump is good.

Climbed grade again later and boiled over. Back to dealer.
They took car out and got it hot, but didn't boil over. Say all is ok.

Drove home from Santa Rosa on the level way home. Ran the car hard, to get it hot. Car didn't get hot and didn't boil over. Coolant level was unchanged.

Week later went back over mountain and boiled over again.

Now they say it is a head gasket and I should replace the motor.

QUESTION????

How can I have a head gasket leak and not cause the cooling system to be over charged/pressured and not blow it out, unless I climb a mountain? Doesn't make sense to me.

I tend to think a sensor is not telling the fan to come on, maybe the high speed setting has failed. Maybe they left a air bubble in the system and the temp sensor can't read the water temp?

Dealership tells me these components works fine. I question it.

Can anyone offer some ideas on how to determine the culprit? Been thinking about a leak doen test to determine if there is a leak in one of the cyclinders via a head gasket to the coolant.

Thanks for your help
Ray

RE: Blown HEad Gasket or is it a bad temp sensor?
 

at highway speeds, you can take the fans out and never miss them. it aint the fans.
if the gaskets are failing, your engine can blow 1,200F hot gases into the coolant, boiling it over only when the engine is heavily loaded.

read our FAQ, there are simple ways to verify the gasket potential for issues there.


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