Oil Pressure High

[Chexi]

My oil pressure has been reading high (between 60 and 80, and sometimes all the way to 80). This is despite the oil being at normal levels (checked on the water warm) and even with the oil low. I changed my oil yesterday after a day out on the lake and was only able to suck 2.5 quarts out (not counting what was in the filter). So it appears that I have a small leak somewhere since when I last changed it I put in between 3 and 4 quarts (also bilge has gotten dirty, but not massive oil all over the place) or am burning oil (although it doesn't smell like I am burning oil and the exhaust does not have that color you typically see when buring a lot of oil). It also appears that I have a faulty oil pressure sensor or the like. However, I wonder if perhaps the oil pressure misread and the leak are tied to the same faulty part. Anyone experience anything like this or any ideas before I start throwing parts at it?

2000 SAN with GT40

[Ryan1776]

Short quick answer.
There is a pressure relief valve in the oil pump. It's probably stuck.

[Chexi]

Thank you. Unfortunately, from the little research I could do on this based on your diagnosis, that sounds like the engine is going to have to be pulled to get to the oil pump.

[Ryan1776]

oh no problem!
OK little more time. I'm betting you didn't get the tube for the pump all the way to the bottom of pan, my rational is this, if there was only 2.5 quarts of oil, I doubt the motor would have ran long without spinning a rod bearing!

I'm not 100% sure but you could definitely be right and you'd have to pull the motor to get to the oil pump.
Now, that's not to say it can't be done, just probably not easily "in boat". There are only two bolts that hold the pump to the block and could be pretty "easily" accessible if you can get the pan low enough. Then there would be some twister action to maneuver the pump out. IF you can determine that this is for sure the issue, I'd definitely try it first. Worse case, you don't get it and pull the motor anyway.
You can check a bad gauge by screwing in a manual gauge right where the old sending unit is, and see what it reads. Not too expensive maybe 50 bucks, but that's CHEAP insurance and money well spent to make sure, not to mention you start your own diagnosis kit.

How long did the motor run while you monitored those psi numbers?
What grade of oil do you use?
What was the engine temp?
Varying RPM didn't change it much?

As point of interest, in case you didn't know, rule of thumb is 10psi for every 1000rpms.
Now, I talked with a pretty smart tech guy at Melling (oil pump manufacturer) he told me that NASCAR guys run around 50-60psi and those guys are turning 8grand! The reason is two fold. 1-The machine tolerances are so good anymore that the high volume/high pressure pumps aren't needed...which leads to point 2-those high pressure/high volume pumps eat horsepower. Those guys need every hp they can get. So they are getting sufficient oiling at less pressure and saving HP.
Now I know someone will chime in and tell me "yeah but they tear down their motors every race", true they do, but we don't beat the ever living crap out of our motors for 500 miles at 8 thousand rpms.
Again, just something interesting.

Hope this helps some!
Ryan

[Chexi]

Thanks Ryan for the detailed post.

I sucked the oil out of the oil pan tube using my vaccum pump and a 3/8" to hose barb connector. I did not go through the dipstick.

I have run the boat basically all summer (49 hours) with the oil pressure reading between 60-80psi. Boat has run flawlessly, with the only exception being when trying to surf 1 time. I heard a sound that sounded like slipping twice while trying to get up to surf speed and backed off. I'm running a spare prop while my high torque prop is in the shop getting reparied, and I chalked it up to just not having the right prop on for that amount of ballast.

I'm going to check under the motor where the oil pan hose is connected to see if there is a small leak there (based on another person's suggestion). I may have 2 separate issues going on, and might as well eliminate the easy stuff first.

Oh, I am running VR1 40W oil.

[Ryan1776]

Wow. Man that's pretty odd about where you drained the oil.
Keep me up to date on where you find the oil! lol

[Chexi]

I have ordered an oil pressure tester to see whether my pressure is really high or whether my sensor and/or gauge are giving false reads. On that note, I assume that the oil pressure sensor is the same as the oil pressure switch and that that is near the oil filter. When I remove this sensor, should I expect a deluge of oil to flow out (engine off)? Hopefully not, but I wanted to check to know how fast I need to make the switch between sensor and tester. Also, if I have the location wrong of the part that I need to remove, please let me know.

I am assuming that once I get the tester on, I can just start the engine normally (in the water or on a hose) and take an immediate reading and then again after the engine has warmed up. Any other magic to this? The PCM manuals are not very helpful.

My goal here is to make sure I actually have an oil pressure problem before taking the boat to the dealer to have the oil pump (or oil pump pressure relief valve) replaced, since that may involve pulling the engine and will certainly involve me having no boat for a few weeks minimum.

[ski4evr]

Pull your sending unit out, screw in one of these, http://www.grainger.com/product/PARK...Code=P2IDP2PCP, screw the sendng unit, and your pressure gauge in and fire it up. you can read both at the same time. Not sure if it is 1/4 or 1/8 pipe thread, but napa will have something like it to fit.

[TRBenj]

Why do you suspect a problem with 60-80psi of oil pressure? All of my ford windsors always run similarly high pressure with 15w50 oil. Pressure does not fluctuate with rpm, unlike my chevies. I believe this to be perfectly normal.

[Chexi]

I have an update. I purchased an oil pressure tester, hooked up the boat to a hose, and gave it a test. Reading at idle as about 53 psi. Rev'd (in neutral) to about 2900 rps and psi crept up a little, but never reached 75 psi. Probably didn't even quite hit 70 psi. The took the boat out the next day and dash gauge started off at 60 psi at idle and got up to about 70 - 75 at 22 mph while the engine was still cold. After warming up, dropped down to run between 50-65 psi. So a change of oil (same exact brand and weight... Valvoline VR-1 straight 40w) seems to have fixed my problem.

The reason I was concerned was because after I changed the oil at the beginning of the season, when the engine was cold I was often pegging the dash gauge at 80 psi when running at boarding speeds and it wouldn't often drop below 70 psi when idling. When the engine warmed up, sometimes it would drop a little further, but often I would be runing between 70-80 psi, which is high per the manual (and my old 99 Air just stayed at 60 all the time)