redstinger

UPDATE! Have had the boat out every weekend for the last 6 wks, still running strong....at 10-20 psi hot oil pressure!!! No noise from engine at all.

When I first noticed back in May that the oil press was running low, I also noticed a dropoff of about 10 mph on the top end. Power out of the hole still good though. it is possible that my lifters are not filling up with oil and therefore not lifting the valves, therefore no top end power?

redstinger

Boat still running. no noise from motor yet. yesterday 15 psi at 3200 rpm.

cloudmaster_321

I know when I had my oil up to 260 degrees the past weekend on 20w-50, i thought 41 lbs @5000rpms was a little low. Now i'm not so sure, sounds like it is normal for the temperature. Probably just need a better oil cooler.

redstinger

Well I made it to Labor day without blowing up the motor, so I pulled it a few wks ago to rebuild and stroke/bore to 489....my engine builder called me and said he could jiggle the crank up and down...he's never seen so much play !!! He said if I didn't rebuild when I did it would have blown up pretty soon!! No wonder no oil pressure. Bearings were ground own to nothing. 2 valve springs dead also. 489 with cam/valvetrain from RM builder will be going in next week. Going from a 454 runnning at 50% to a fresh roller 489...Lake is full, its going to be a great summer!!! Thanks for all the suggestions.

almalare

I have (2)factory rebuilt 7.4LX MPI engines that are 2 years old and only have 150hrs on them.My pressures are identical to yours.I had to replace a piston recently and I had a look at the rod bearing.It was perfect ..like brand new.I was a little concerned as well with 10 psi idle and 40 psi at 4400RPM but maybe when the 10 psi/1000 RPM rule was invented oil was not as good as it is now and of course we have synthetic now

Monkeyron

Well I had mad a few trips on the Motor with oil pressure @ 50-60 psi @4500 all day. Water temp won't hit 130 so I'm replacing the Stat before next trip. Anyway, the Guys that are running low pressure Beside Redstinger's near disaster, change out your Oil filter to the K & N HP-3002. I did and I picked up 20-25 psi.
Some of the Oil filters out there don't flow well enough for this Big Motor. I was using a short Mobil-1 filter. Forget the short filters, go long. More surface area.

Now for my next big Challenge, go from 2 MPG to 6 MPG. Offset with Plasma & Hydrogen.
M~R