klmken

I just did my first oil change ay 10 hours on my rebuilt Gen 4 454 (.060 over; 9.5:1 compression; stock merc heads and intake).
The oil was black and I haven't run over 4450 rpm and that was for 30 seconds. I have kept the motor between 3000 and 4000 rpm for most of the first 10 hours with a few lengthy idling periods. I installed a new melling HV oil pump during the rebuild. I am unable to build more than 35 psi oil pressure once the engine reaches normal operating temp..170 degrees and steady. Used straight 40 for break in and now am on 10-40 for the next 10 hours before going to 15-50 Mobil One

Memorial day weekend I popped the main hose from the thermostat to the circulating pump on the motor )@ 4200 rpm and the motor died. I am not sure if it took a gulp of water or overheated. The temp guage was actually going down before the motor died from lack of water enterings the thermostat housing. I reattached the hose and the motor cranked right back up and ran fine the rest of the trip. I feel like I was getting 45 psi oil pressure before the hose incident but am not positive and am worried that there is now a problem...
What are the scenarios for low oil pressure given these circumstances? Is it possible to have run the engine hot enough to have hurt the oil pressure? I am going to try a new sending unit and guage shortly to see if the guage is faulty as well as install a oil temp guage.....
Thanks,
Ken

razor1115

If you feel you've overheated the oil, definitely change it. You may have started breaking down the oil, especially if it's black. You're oil pressure should return after that. I had a similar problem where I lost a belt, it flipped around a took out my H2O pump belt at the same time. Engine got hot but made it back in OK. Oil pressure was low after that. Changed oil - pressure back up.