oil pressure

1986 454 crusader oil now at 65. Normal 40. Direct manual check confirmed the 65. Oil is clear. 10/30. Replaced filter.
I believe this higher pressure is concerning. Could oil pump be the problem?

55 psi is close to ideal for that engine. Any thing greater may cause cavitation at/near oil galley directional turns.
The oil pump itself is a twin gear semi-positive displacement pump..... capable of several hundred PSI.
The oil pump by-pass valve controls the final pressure.
The oil filter base incorporates a by-pass valve for use when filter media becomes saturated.
A saturated oil filter will not cause increased oil pressure.

Have you tried connecting up a known-to-be-good mechanical gauge?


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The manual check was my mechanical Ck. Confirmed meter reading of 65. Could you tell me more about the by-pass valve? Or any other thoughts.

at idle or cruise rpm?

vary with RPM (or temp) or constant across the range?

Rilor said:

The manual check was my mechanical Ck. Confirmed meter reading of 65. Could you tell me more about the by-pass valve? Or any other thoughts.

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The by-pass or relief valve is very simple.
The gears are capable of producing several hundred PSI. We do not want hundreds of PSI.
The relief simply allows excessive pressure (such as any over 55 psi) to return to the suction side of the gears.

40 is what I've seen on these, but not saying 65 is a huge problem. It will be marginally more stressful on the drive rod. Dropping the pan is the next step if you wanted to get into the pump/relief valve. But, that normally requires you to pull the engine in a boat. The relief valve is quite bullet proof. I wonder if a piece of metal lodged in there.
I would do this. Tear open the oil filter, and look for metal. If clean, I may just run the engine as is. There is some possibility it would self-clear. If you do see metal, I would tear down that engine and fix it. Worn cam lobe would be an easy fix, others, not so easy.
I don't know where you live, but the stress will be highest at cold starts. I'd also seriously consider running a wide spread synthetic, like a 5W30. And avoid a straight 40 for sure.

ps; if the relief valve is indeed stuck, then oil pressure with low rpm and hot oil may become too low. Have you measured that condition? If you can't maintain, lets say 15 psi at 1500 rpm/trolling speed, that will do bad things to the cam, in particular.

Avoid straight 40?? My 95 454's say to use straight 40. Both engines rebuilt when they had abut 1k hrs. been using delo 40 in old and rebuilts for last 10 yrs. Oil pressure is a rock hard 40psi at cruise (3200 rpms)

kevin_z said:

Avoid straight 40?? My 95 454's say to use straight 40. Both engines rebuilt when they had abut 1k hrs. been using delo 40 in old and rebuilts for last 10 yrs. Oil pressure is a rock hard 40psi at cruise (3200 rpms)

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My advice was targeting a defective engine stuck at 65 psi. I ran Castrol HD40 for many years in my 454. Then again, my cold starts were typically 85 to 90 deg ambients. btw, is 1000 hours a long time??

40 at start at idle rpm. Once increased to 1500+ pressure jumps to 65 and remains there even when returned to idle.
This reading of 65 does not vary at all even when under way at 3200. Temp. holds at 185.

Is this a new problem? Seems more likely to be an aftermarket addition to the engine by past owner

Rick,
I am told there is a pressure relief valve in the oil filter fitting as well. Fact or fiction?