I am testing for a cracked head gasket by filling each cylinder with compressed air at TDC and looking for bubbles in the coolant. But then I realized that even though my radiator is full, the coolant still does not cover the entire filler neck.

Since, the air gap at the top of the neck is higher than the fullest coolant level possible, how am I ever going to see bubbles? Or does this test work even though the coolant is not at the top of the filler neck and an air gap is pressent?

Thanks

 

Does anybody know how to perform this "Bubbles in the Coolant" Test?

 

I would pull the tstat and tstat housing off and watch for bubbles there since you are putting air in at the heads. Otherwise I doubt the air would make it all the way to the radiator cap.

 

True, true... That make alot of sense. I also had doubts about the bubbles making their way up and around that return water hose.

I'm gonna take that tstat off.

Good idea, Thanks TPIgirl.