HIGH oil pressure at all times mercruiser 140 1977

[bassjbl]

hello, I recently purchased this boat, everything looks great and it starts right up, buuut. withing 2 seconds from starting the oil pressure guage pegs out at the top"80psi" and if I don't shut it down it will blow the seal off of the oil filter.. if I shut it down and restart over and over until temp gets up to 150F I can run it but it is still at 79PSI this is all at idle, I don't believe a bad oil pump pressure relief is the culprit, because pressure shouldn't need to be relieved at idle.... have tried SAE 30 rotella, standard 5w30, and 20w40 quicksilver all with the same outcome, also with Mercruiser oil filter and fram ph30. HELLLLP!

 

[GA_Boater]

Welcome aboard.

Maybe the gauge or sender is the culprit. It would be worth testing with mechanical gauge connected where the sender attaches to the block.

 

[gm280]

I concur with GA_Boater as well. Before thinking oil pump, test with another gauge and see. Even a high output oil pump won't be reading that high at mere idle speeds. So either the sensor or gauge could be defective... JMHO!

 

[bassjbl]

I skipped that test due to the oil filter seal blowing out, shows me the pressure is high, I have checked for double seal and corrosion around fittings

 

[Watermann]

My bet is on that Fram oil filter get rid of that POS and put on an AC delco.

 

[GA_Boater]

I thought from reading your first post you shut it down so the oil filter seal wouldn't blow out. Oil pressure is higher with a cold engine, so the relief valve does come into play if the pressure is higher than the relief pressure.

When you changed the oil, what did it look like?

 

[bassjbl]

It also blew the seal of a mercury oil filter. Ooh and also did once warm when I tried to throttle. When I bought the boat there was water in the oil, when I drained it was clear water then decently clean oil, no chunks, no sludge, no rust

 

[Watermann]

Water that was separated from the oil after sitting is not good, the oil pick up was sitting in that water. You have a restriction somewhere if not the oil filter then somewhere else possibly due to the water intrusion. Did you find out where the water was getting in and make the repairs if not you could just be wasting your time and money.

 

[gm280]

Well obviously whatever has your oil passages stopped up is after both the oil pressure sender unit and the oil filter. So you need to locate where the blockage is and clear it. Because even with that high pressure, there are parts of the oiling system running dry...

 

[bassjbl]

Boat was uncovered without spark plugs in, I did all the appropriate steps for freeing up pistons, drained and put in fresh oil, hand cranked many times with atf in cyls, changed oil again, cranked with starter, changed engine oil, hooked up to muffs, started motor, then had the oil pressure issues, warmed it up, ran for 5 mins, oil change, tried again still had same pressure issues.

 

[bassjbl]

Gm280, I was thinking clog as well, I am taking off the valve cover and oil filter and wanting to try clearing the oil galleries between. I cant tell if oil is getting to the valves, it looks like it is, but may just be splashing arount the oil that is up there from filling.

 

[GA_Boater]

Time to pressure test the cooling system. Water in the oil for a long time can cause exactly what you're seeing. I know.

 

[bassjbl]

GA-boater, I am confused what would pressure testing the cooling do?

 

[GA_Boater]

Tell you if the block or exhaust manifold is cracked leading to water in the oil.

 

[bassjbl]

Well after my oil changes, running the boat did not cause my oil level to go up, or down, nor did it milk up the oil, also, wouldnt that cause low oil pressure?

 

[GA_Boater]

From what you've told us, you haven't used the boat. Just kept starting it and turning it off. No actual running the boat.

You have to ask where did the water come from?

 

[bassjbl]

I posted to a response from someone else that the boat was sitting uncovered with spark plugs out, I am sure that was the cause

 

[bassjbl]

When it was warm I ran it for about 5-10 minutes but that was all "on muffs"

 

[GA_Boater]

Why was she sitting with the plugs out? Obviously something was wrong with her. I wonder if she was making milkshakes?

 

[bassjbl]

I am unsure as of yet, want to find out what could be causing this oil pressure issue so I can continue testing other funtions