2001 Deville coolant expansion tank

[treybarnes66]

I have recently purchased an 01 deville. I've probably put 500 miles on it since I bought it. I noticed every time I park it at home the expansion tank pukes abdicated have been losing coolant because of this. With the expansion tank open while running there is steam coming out and when you kill the car it bubbles over and coolant is lost. I was told this is because I have a blown head gasket. I don't really understand why, I'm thinking that it would puke out during acceleration while the pressure is being forced into the system.

 

[jimmythekid1]

On what your explaining alone I couldn't condemn the headgasket. Although it is common for that era of northstar engines.

What is definitely causing the over flow is trapped air in the system. While the engine is running the water pump tends to circulate most of the air while the engine is running. Once the engine is shut off the air tries to travel to the top of the system, hence your overflow.

Now the question is where is the air coming from? A stuck closed t-stat could inhibit proper circulation. Or combustion gases could be the culprit too. I would have a repair shop do a chemical "block check". That way you can have confirmation that the head gasket is indeed blown.

James