Originally posted by shogun8
This can be caused by worn pistons, worn rings, bad valves, flooding or worn bearings. The rear main bearing may be
severely worn. When checking for flooding, look at the oil sight glass. Does the oil look foamy or clear and then turns foamy and back to clear? Are the heads too hot (sizzle when sprayed with water)? Is the crankcase too hot (105o to 125o F is normal)? Does the oil leave on start up and doesn't seem to come back? Check the suction pressure. Suction or head pressure may be too low to bring the oil back to the compressor. Has the compressor been running unloaded for an extended time? When a compressor is unloaded the gas velocity and line sizes are incorrect
resulting in poor oil return. Is the crankcase pressure too high? Check the difference between the
crankcase and the suction pressure.