As seen in Speedboat Magazine’s
September/October 2021 Issue.
Low Oil Pressure
I have a 2000 Mercury carbureted HP500 with an M3 ProCharger in my boat. Last winter, after 470 hours of operation, I had the engine rebuilt. I had asked the builder to install a high flow oil pump; however, I believe he installed a standard Melling M77 oil pump. Prior to the rebuild, my engine had oil pressure of 70 to 75 PSI at WOT (5,000 rpm). Now, the highest oil pressure is 45 psi.