high oil pressure

trx680 · November 10, 2013

About 6 months ago I bought a 91 Suburban, 350 w/129000 miles. The engine runs great, doesnt smoke or loose oil. I'm sure conventional motor oil had been used in it. I use synthetic in everything. So when I changed the oil I used Mobil 1 10w30 synthetic. I don't drive the truck often, maybe once a week. Lately I noticed when driving at highway speeds the oil pressure guage shows high pressure. It might creep up around 60psi, or it might even max out. I checked the oil and its reading full.

Any idea what causes the pressure to jump so high? Is this harmful to the engine?

thanks !!

dodge123 · November 10, 2013

Possibly the oil pump pressure bypass is getting stuck partially closed? I dont know if you year truck has the same pump as mine. Since I purchased mine in 2011 with 213k, I would get low oil pressure lights every day when cold (2-3 psi). I did some research and youtube'ing and decided to have the dealer replace the pump (time vs money

). The pressure is now normal (40 idle 60 under load). My suspicion was confirmed, the pressure relive plunger is steel and the pump housing is alum. The plunger can get stuck open or shut due to metal to metal wear over time. Mine just happened to get stuck open.

gmtech4 · November 10, 2013

Have your mechanic put a master oil pressure gauge on the engine to start the diagnoses

Badass69 · November 10, 2013

Garbage instrument cluster or sending unit. Verify with mechanical gauge.

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Doug_Scott · November 13, 2013

Pressure would have to be a lot higher than 60psi to cause damage(assuming a name brand oil filter). As others have said, check oil pressure with a mechanical gauge. If doing this yourself, you may as well grab a oil pressure sender unit since you will be removing the old one to test oil pressure. Not much sense having to pull it twice.

trx680 · November 22, 2013

I changed the oil and filter. Mobile1 5w20 synthetic and fram filter. Stil having the problem. Depending on engine rpm it might be normal or the needle might be buried high.

what is this guage I can use to check the pressure? How is it done?

thanks !!!

knightlife · July 7, 2014

just encountered this same issue with my 05 sierra HD crew cab (6.0). I did a motor flush, took the pan off, clean the small film of sludge off of it, and then replaced the oil and filter.

upon startup it went to its normal 55-60psi. then shot up to full pressure momentarily after. most likely the pump causing it. the motor is getting oil across the top end on both sides (verified with a boroscope), so Im going to say its probably the pump.

any other ideas? lol

daxr · July 8, 2014

The main idea would be that the factory gauge/sender isn't designed to be especially accurate. That's why pulling the sender and hooking up a good mechanical test gauge would be the first step. It could easily be a non-problem.