Herb, I would first check the guage with a known proper operating guage. Yours might be wrong... By increasing the releif valve spring tension, you could be pumping too high a pressure .. this can destroy the bearings from errosion---like using a pressure scrubber....
The relief pressure valve does not operate until about 60 psi, preventing overpressure.....Unless it is stuck open , it will not affect oil pressure on the low side. The Continental manual specifies a minimum of 10 PSI Idling, hot....... and a maximum of 60 Psi at cruise RPM, hot..... anything in- between is probably OK...... if oil temperature and consumption are within bounds...... The 10 psi at idle, hot, indicates the condition of the engine bearing clearances.....lower than 10 indicates excessive clearance. What kind of oil temperatures are you running... Should be about 180- 200 deg F,(max 225) depending on outside air temp......Again --may need to confirm with an alternate guage....Too high oil temp, means thiner oil, and lower pressure. The theory of oil lubrication is that the pump simply places oil in the bearing clearances, the rotational movement of the shaft actually creates the dynamic film of lubrication.......so, pressure is not so important ---unless you use the oil to operate a constant speed prop, etc... The oil escaping from the bearings, creates a spray of oil mist that lubricates everything else.... Excessive blow-by in one or more cylinders, due to worn or stuck piston rings. Check compression, and listen at the oil tank for excessive blow -by noise with pressure in the cylinders..... some blow by is normal.... also observe the crankcase vent line for excessive vapors and oil wasting... Remove and clean the oil pick -up tube, - inside the oil sump --- it could be clogged due to oil sludge....., or could be loose in the housing, allowing air to be sucked into the pump... Clean the carburetter mixture control discs.. you could be running very lean, thus hot; resulting in hotter oil than normal, thus lower viscosity. Try multi - vis oil to help with hot engine; but better to solve the "hot Engine" problem , if there is one. Proper placement of engine sheet metal --- and proper sealing of the cowling, so that air coming into the cowling is passed thru the cylinders for cooling, and not lost out the back of the engine compartment. Engine magneto timing at proper setting...retarded or advanced timing will cause overheating or pre-ignition......excessive heat.... Oil pump gears worn excessively ----not very likely. Possibility of exhaust system blockage......muffler baffle, or stack internal failure.. Airplane out of rig/balance, so that the airplane must be flown at full power settings to perform as desired; deflecting cooling air to engine.... remote, but possible. Hope these ideas help, and stimulate more comments as to possible problems... Fly Safe - Have Fun, Regards, Harry Francis 93530 Blacksburg, VA
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