Once again tried to find oil leak. Seems dry at back of engine around accessory case, but some wetness observed under engine block itself. After 12-minute test run no oil leaks observed.
Ran up engine and took notes as follows: Test conditions: OAT 75F, no wind. Minute RPM Oil Press, notes 0 800 Up to 42 in LT 10 seconds. Two gauge “jumps”. 1 800 42 2 1000 42 6 1000 30 7 1000 25 8 1500 30 9 2000 30+ 10 2000 25 Oil temp 100 11 1000 13 11:30 800 5 11:45 500 0
Removed top plugs. See photo. Cylinders 2 & 4 normal color, 1 & 3 appear rich. Performed warm compression test, all cylinders 78/80.
Thoughts re: sinking oil pressure: Gauge inaccurate? It does jump around a bit. Ordered new gauge. Relief valve sticking? Unlikely, but will replace spring and check mating surfaces. Ordered spring. Something wrong about oil? Could try a multi-vis. Poor fitting oil pump cavity/gears? I think I checked to be within tolerances when I reassembled engine. Only way to check is pull the engine and remove accessory case. Internal leakage within the case? Bad bearings? Something incorrectly assembled. Would need to spilt the case to find/correct. Ugh. Why does the problem seem to be getting worse? Is this a clue to anything?
