Sounds like a head gasket. Get yourself a cylinder leakdown tester (can probably rent from local autozone or whatever chain parts store) and put air into each of the cylinders (after you've manually turned the engine so both valves are closed) and look for the leakdown percentage. If it's a high percentage, listen at the radiator fill cap area with the cap off, if you hear that air there, you've probably got a head gasket problem.
|