PCM 454 Oil Pressure?

What is "normal" oil pressure on a PCM 454? My boat has 1250 hours, and my gauge reads just about 20psi when at normal operating temp at idle, and 45-50 at WOT. The oil pressure dummy light and alarm will chirp at me coming back to idle. Sometimes on solid at idle, if it's warmer and pressure settles barely under 20 at 500rpm. Oil is already a little heavier Rotella 15w40.

This all seem a little low to me, and I had a buddy onboard that has a Mercruiser 454 based engine that run nearly double those numbers all the time. But his engine is a WAY different beast - the Mercury "Blue" 500 Bulldog in a Fountain...

I guess first step is to verify these numbers with a mechanical gauge, but what should i really be expecting?

My 454 with about 800hrs holds 40psi at idle, and 60psi+ at any engine speed above idle. Your numbers do seem a little low, but not horrible. You have already verified your oil pressure since you have a gauge, but swapping it out with a known good gauge won't hurt to double check pressure readings. There is a very old automotive rule of thumb, that dates back to when these engines were manufactured. 10psi of oil pressure for every 1000rpms being acceptable. So at 5k rpms you should have 50psi, 3k rpms 30psi and so on. If you choose to use this age old rule of thumb, then you are still with in acceptable limits, albeit on the lower end of the spectrum.

In all reality, with the thicker oil, and still showing lowish oil pressure, your engine is probably getting worn out and will be in need of a rebuild sometime in the distant future. It's quite possible that it will run just the way it is for a very long time, a lot of it depends on how you use your boat. If it were me, i wouldn't lose much sleep over it because there isn't much you can do to fix oil pressure with the engine in the boat. Keep an eye on it and enjoy it as you would normally. Rebuild or replace when the time comes.

Just to throw it out there but you have checked your oil level

As a guide, you should have at least 10psi per 1,000rpm. So, the numbers you gave are fine, so long as the gage is correct. If you have 20 at idle but are still getting the chirp, the low pressure switch may be going bad.

Just don't be like my Windsor and have 20 psi at 6000 rpm . Lol buy a manual gauge and verify . Real easy to blow a bottom end without correct oil press


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LOL, yes it has oil, but thanks for thinking simple for me! I've put almost 200 hours on the boat in 2.5 seasons now, change the oil twice a season, and it has been like this since I bought it. I wasn't concerned with it until my buddy raised the red flag. I'll take my mechanical gauge this weekend to verify, and stop worrying about it. Maybe I'll unhook the buzzer... I can also bump my idle up a touch now that I'm running a 13x11 prop - 500rpm was coming out to be 3.5 MPH int he idle zones last weekend. I could stand to move jsut a little quicker at idle anyway.

I went down the rabbit hole a couple of years back and read a bunch of stuff on bobstheoilguy.com. One mistake a lot of people make is putting thicker oil in to get the oil pressure up. Flow is more important than pressure, so thicker oil may bump your pressure up a bit, but it can lower your flow. Oil is not only for lubrication but also for cooling. Just my .02

Isnt the oil rating higher? Mine is 20w50 iirc for my 350

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My 454 is freshly rebuilt and I'm at 30 at idle and about 65 at speed. Your numbers certainly don't sound too low for a "mature" engine. You're running the right oil and those numbers are fine until they start dropping more.

Verify the ground to the gauge is good. Take note if the pressure drops or rises when you turn on electric loads. This is a sign of a poor ground.