Oil pressure????

[James2003x]

Hey guys. I recently purchased a 2004 Tahoe lt with a 5.3 I did not notice before today but when stopped or in park the oil pressure gauge reads about 20 when driving about 2000-2400 rpm it sits right at 38-40

Should I start looking to replace the oil pump?
I'm fixing to take a trip in two weeks to Houston Texas and would really hate to lose all pressure while out of town.

 

[07burb]

Does it stay steady at those numbers or does it start higher and gradually go lower to those numbers?

 

[James2003x]

Does it stay steady at those numbers or does it start higher and gradually go lower to those numbers?

It will fluctuate pending rpm but if I hold it steady the needle doesn't move that I can see anyway.

 

[Prospect62]

My truck has 296,000 miles on the original motor.

Cold starts, the oil pressure goes to 40 psi and hangs out there for a few minutes. Once it warms up it drops to about 35. While driving, under load, at any RPM it swings from 25-35.

Seems a little low for my taste but it's still kicking.

 

[Jeff M]

The short answer is 20 psi is okay at idle as long as it comes up as the engine RPMs increase.

The reason why this happens is...Engine bearing clearances open up as a the engine wears. As this happens there is a higher flow of oil that passes through the engine and therefore drops the pressure. The pumps are fixed displacement with a spring loaded pressure relief valve (that is what keeps the pressure below 50 at higher RPMs). The rate at which this wear occurs varies greatly and is typically tied to oil quality and cleanliness. If the oil was not changed in a timely manner or allowed to run low engine wear will be greatly accelerated. This is something you really need to watch for when shopping for a used vehicle. I hope this helps.

 

[James2003x]

Thanks Jeff. That's at lease some good news. The tahoe has 165kiles on it. So I knew the pump could have been a issue.

 

[Jeff M]

My 2005 has 160k miles on it and the pressure is still holding strong. I have had it since it was new and have run nothing in it but Mobil 1 synthetic. I love the truck and hope to see it last for years to come. If I were you...I would purchase a pint of Rislone and add it at your next oil change. Make sure to use a high quality oil filter such as Wix or Purolator, I would change the filter again in ~1,500 miles. This will help remove any fine debris from the system which tends to builds up if maintenance is neglected. Again this is just what I would do, good luck!

 

[vernons]

james,
have you changed the oil and filter since you've bought the truck???? my 01 tahoe with 132,000 miles has always held 40 lbs idling and 40 to 50lbs under normal driving... then a few wks back i noticed mine started dropping to about 25lbs idling. and come back to about 40 driving.. started reading about members on different chevy forums reporting problems with those e-core oil filters.. which i had a pf-61e delco e filter on mine... so when i changed oil at normal 3000 miles with new filter.... the oil pressure problems disappeared... back to idling at a steady 40lbs.. so before doing anything drastic try a oil change with a good wix/napa oil filter... might be suprised at the results....
keep us up to date...
to me it's apparent something went defective in the e-core oil filter... as oil pressure still great after 2wks with the oil change and new filter..

 

[New Tahoe Owner]

Low Oil Pressure too

Had the oil changed last weekend and as soon as I started the vehicle I noticed that the oil press gauge was acting up. Normal pressure, then it would drop to about 20 then gradually went to 0. Drove a little and it gradually returned to 40 psi.

Next day, start the truck, head off and its constant 40-50 psi for the first 8 miles then tanks to 0. Same thing return trip.

I was thinking it could be that the oil sending unit has gone bad.

Is there a way to test it?