Originally Posted by michaeld

gmercoleza,

The compression test could indicate a blown head gasket to someone who knows how to read the gauge. But there are two other ways that are better:
1) A block test, using a chemical that "sniffs out" exhaust gasses in your coolant.
2) A pressure test. The nice thing about the pressure test is it costs you nothing (you can get a pressure tester at Autozone on their loan-a-tool program). I would do the pressure test three ways:
a) Install the pressure tester to your expansion tank and pump to the pressure on your cap. Wait about five minutes and see if the pressure holds.

b) Start the car and let it get to operating temp, then connect the tester. You are looking to see if the pressure goes up (particularly above the psi of your system). The engine psi is a lot higher than the cooling system psi, so if there is a leak, your cooling system psi will spike.

c) Let the car cool down. Install the tester and then start the car. You are looking for fluctuations in the gauge. If you have a blown head gasket, the needle will fluctuate as the engine rotates to the cylinder that has the blow-out.

I would try to rule out a blown head gasket before spending a lot of money replacing what COULD be wrong, only to find out what you needed all along was a $3000 head gasket replacement.