Really high oil pressure

[Spencer2009]

Hey guys my hoe has been recently making really high oil pressure for the first ten or fifteen minutes after being cranked cold. It stays above 75lbs for the whole fifteen minutes or so then drops down to the 40-50 range after the 15min. Is this a major problem? I think i know why its doing it cause i used 5w-30 last time instead of the 10w-30 i usually use. Im just about due for a change but i just wanted to see if this was a major problem that i needed to fix right away.

 

[faze]

5w-30 and 10w-30 are the same oil unless the temperature drops below freezing and then the 5 will stay a little thinner. The weight of an oil is temp dependant so cold starts all oil will be the same unless it's really cold or your using a 20w50/15w40.

I would guess either the sending switch in the engine is going...cheap easy replacement...where I'd start; or, the guage set is starting to go...on my 95 the op indicator was the first one to begin acting up...then the volt guage.

 

[DJTricky]

thats not the reason. its just the thickness of the oil. when its colder its thicker so squeezing that through the tight clearances that it has to will cause a higher pressure. but like you said once it warms up the oil thins out and the pressure drops. its not bad at all. if anything its good. your engine needs more oil to be in there when it first starts up.

 

[Spencer2009]

ok thanks man i wasnt sure so now i feel better that i know its nothing that will damage the engine

 

[faze]

DJ...the only way your statement could be true is if the temp is below freezing ... otherwise you're entirely incorrect.

 

[DJTricky]

DJ...the only way your statement could be true is if the temp is below freezing ... otherwise you're entirely incorrect.

you sir are vary incorrect in saying that my response to his question is incorrect

the oil is thick no matter what. but the cooler the oil the thicker no matter what temp it is on first start up.

the biggest determining factor in oil pressure is oil clearances . . . now with this said.

clearances are tighter when the engine is cold. once it warms up the clearances expand allowing more oil to flow through them. more oil flow means lower oil pressure.

 

[faze]

DJ you're just plain wrong about multi-weight oil ... above freezing, with a cold engine, 5w30 or 10w30 will be the same weight...a 5 w stays thinner longer if it gets cold.

Further, it's not just tolerances that create oil pressure...the proper weight oil is equally important...at Normal Operating Temp a straight 10w oil would be like water in your engine and probably wouldn't even stick to the dipstick. That's why a multi weight oil gets thicker as it gets hotter, ie a 10w30 goes from 10 to 30 as the engine warms.

No doubt his engine oil pressure is higher when cold but his question had to do with recent "really high oil pressure"...my advice still stands: sending unit or guage.

The reason it's important to look at these is when the electronic o.p. guage started going bad in my GM truck it began to read high, ie the guage becomes unreliable and will need to be repaired so he has an accurate reading.

The real question is what is his hot idle oil pressure...it should be around 20 in drive.

 

[eeehabt]

DJ you're just plain wrong about multi-weight oil ... above freezing, with a cold engine, 5w30 or 10w30 will be the same weight...a 5 w stays thinner longer if it gets cold.

Further, it's not just tolerances that create oil pressure...the proper weight oil is equally important...at Normal Operating Temp a straight 10w oil would be like water in your engine and probably wouldn't even stick to the dipstick. That's why a multi weight oil gets thicker as it gets hotter, ie a 10w30 goes from 10 to 30 as the engine warms.

No doubt his engine oil pressure is higher when cold but his question had to do with recent "really high oil pressure"...my advice still stands: sending unit or guage.

The reason it's important to look at these is when the electronic o.p. guage started going bad in my GM truck it began to read high, ie the guage becomes unreliable and will need to be repaired so he has an accurate reading.

The real question is what is his hot idle oil pressure...it should be around 20 in drive.

I totally agree with you regarding oil viscosity. I've recently bought a 2007 Yukon XL. I noticed a knock that comes and goes at idle. I'd really like to know the normal reading for the engine oil pressure at idle in PSI. Could you help me with that? Do you think I need new crankshaft bearings?

 

[SunlitComet]

there is not really a set pressure for a given temperature for engines. tolerances in an engine can vary the pressure a bit. there are minimums tho. grab a data sample of the rpm, oil pressure, engine temp and outside temp when you can and post here. a sound clip or video of the sound when idling would be ideal as well. if this gets way to involved a thread in the correct year sub forum will be needed but will help you out here as long as this thread is not split up.

 

[eeehabt]

Hi,
Yesterday I let the engine cool down and started changing the oil pressure sensor that is located at the rear side of the engine block behind the inlet manifold. It was a pain in the a** job as I could see nothing. I barely could insert my right hand to disconnect its plug. I disconnected the fuel line to make the job easier. Luckily, I have a friend in a spare parts shop that told me there was an oil filter placed underneath the sensor. I took a copper welding wire and formed its end like a sharp hook and struggled to pull the filter out. Eventually, and after half an hour of persistence and cursing the designer of the engine, I succeeded in pulling it out. It was 80% blocked with hard oil residues. I flushed, cleaned and aired it until it returned as good as new. Then I reassembled the filter followed by a new sensor. The efficiency of the oil pressure has improved 90% and now I can safely drive it in the way I like. A graph showing the filter is attached.

 

[retorq]

The efficiency of the oil pressure didn't improve, the gauge is now reading correct, that's all. You have the same pressure to the mains and the rods that you had before.