loss of compresion
Asked by mpaul1181 Feb 03, 2009 at 12:01 AM about the 1997 Porsche Boxster Base
Question type: Maintenance & Repair
i have a 97 porsche boxster that only has 35 pounds of compresion in the # 3 piston.what could be the cause of this issue. i think it may be the rings becasue the rest of the cylinders have full compresion.
2 Answers
It could be the rings, but it is most likely the valves or the head gasket, possibly the piston. You could have a chipped or bent valve, if that cylinder was burning very lean it could have burned a hole in the piston. Your spark plug hole may be leaking, check to see if the washer is damaged or broken, if that's OK you are going to have to pull the cylinder head off and physically inspect the valves and the pistons. If that doesn't get you anywhere you should pull the oil pan off and inspect the crankshaft and rod bearings. I don't know how easy or difficult that is to do on a Porsche but in my experience the most likely answer is te valves or the head gasket.
Do a leakdown test to determine with a greater certainty.