Hi there, I've been struggling with an oil pressure problem on my recently put together Rogers.The engine was originally built for a truck and had maybe 600 miles on it before I purchased it and was put together by a known builder who lined up the purchase for me.So , pulled the pan, installed now what I know as an Older Dooley 10 qt pan from what I've been told from Craig at Dooley. The pan does have a front windage tray built in with a trap door, but no rear tray, or scraper.Im using a mercruiser?Style pickup that is at 3/8 off the bottom of the pan. The oil pump is an m77 melling and I'm running Brad Penn 20/50 . Started out with 9 quarts of oil as recommended from GS marine . They said they run better with 9 instead of 10.
Here's the issue..............at start up I have 45/50 psi oil pressure, Once I idle out, and start to get up in the rpm range, say 4500/5000 after 10/20 seconds I lose oil pressure down to 20 psi, it would go lower if I stay in the throttle.As soonAs I let off throttle and let it idle the pressure goes up.I have a mechanical gauge and installed a second gauge to verify and they both read the same while running.Ive been to the lake 2 different times to test .the second was after I pulled the engine, and checked crank bearing and rod bearings , and even changed the pickup and reset height.One other note is that the gauge on my first test would have fluctuations up and down, the needle would bounce a bit before the big pressure drop at higher Rpm.The second test I lowered the oil level by 1 quart and the fluctuation in the gauge went away .So could this all be windage and I need a new pan/pickup , crank scraper ?
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