Oil temp/pressure

My 1946 415-C is on it's second 75 hp engine.
Oil temp on both run 190 on a warm day and
200 on a really hot day here in Kansas City.
Oil pressure on the original engine was 22 psi
on a hot day. The 2nd engine stays at 35 psi hot.
My bet is the oil pump on the accessory case
is worn. Unfortunately that requires an engine
removal to repair.

Do you have an oil filter? If it has not been changed recently, it could be the problem. If not, it sounds like it may need a major overhaul.

Note. A little parallax angle on the gauge makes it look like the colored arcs are incorrect but they're ok when viewed straight on. Same with the oil pressure needle. Pressure is 27 psi.

It finally got hot here in the upper midwest and my airplane doesn't like it. The oil temp is hard pressed to come off the peg on your avg 50 degree Spring day but once the ambient temp rises above 80 or so, things get hot fast and as the oil temp reaches 160 or 170, the pressure starts to drop. When oil temp reaches 170 the pressure drops below the minimum 30 psi as you can see in the pic. The engine is C85 with about 1200 hrs on overhaul. I've tried straight 50W oil and 20W-50 oils with no difference noted. My gut feeling is that if it's not a gauge accuracy issue it's probably a worn pump housing or worse yet, worn main bearings although oil analysis to date has been fine. I change it every 25 hours.

Anyone have a magic solution?

Chris Carlisle
415C, Ser #508
Sioux Falls, SD