Re: COmpression Test
If one or more cylinders reads low, squirt approximately one tablespoon of clean engine oil. Repeat compression pressure check on these cylinders.
Compression Readings -- Interpreting
1. If compression improves considerably, piston rings are faulty.
2. If compression does not improve, valves are sticking or seating poorly.
3. If two adjacent cylinders indicate low compression pressures and squirting oil on pistons does not increase compression, a head gasket may be leaking between cylinders. Engine oil and/or coolant in cylinders could result.
When checking cylinder compression so that the lowest reading number is 75 percent of the highest reading.
If, after checking the compression pressures in all cylinders, the highest reading was 1351 kPa (196 psi) and the lowest pressure reading was 1069 kPa (155 psi), the engine is within specification and the compression is considered satisfactory.
Is it running like it has a mifire? A friend of mine gets a lot of used P71s and if they set for awhile, sometimes when he starts them, a rocker rm will fall off. It produces no noise and it runs rough. Also the 95s wer proen to have valve seals leak acusing oil consumption. They could carbon up and cause mixed readings like that. The rings haven't been known to wear out for at least 400,000 miles with good servicing.