Low oil pressure but no noise

[Leonard country]

I have a 04 yukon with 5.3 was told last owner tried everything to get rid of low oil pressure nothing helped. The low pressure warning is on but truck has no valve rattle ticking or knocking this is the newest thing I've ever owned and only thing with 5.3 always been a 350 guy any ideas

 

[Tonyrodz]

I have a 04 yukon with 5.3 was told last owner tried everything to get rid of low oil pressure nothing helped. The low pressure warning is on but truck has no valve rattle ticking or knocking this is the newest thing I've ever owned and only thing with 5.3 always been a 350 guy any ideas

Did you confirm oil pressure with a mechanical gauge?

 

[swathdiver]

I have a 04 yukon with 5.3 was told last owner tried everything to get rid of low oil pressure nothing helped. The low pressure warning is on but truck has no valve rattle ticking or knocking this is the newest thing I've ever owned and only thing with 5.3 always been a 350 guy any ideas

Did he replace the camshaft bearings? Does the oil pressure fluctuate at all?

 

[Fless]

Post up some details of the rig: mileage, etc., and a list of what "tried everything" means. What repairs or tests have been done?

Had a recent oil report by, say, Blackstone Labs or somewhere else?

 

[Bandit-66]

Did you confirm oil pressure with a mechanical gauge?

This would also be my first option I would do for now

 

[Dbeal82]

I have a 04 yukon with 5.3 was told last owner tried everything to get rid of low oil pressure nothing helped. The low pressure warning is on but truck has no valve rattle ticking or knocking this is the newest thing I've ever owned and only thing with 5.3 always been a 350 guy any ideas

I had a similar situation with my 6.0L. I changed oil pressure sensor and screen. Truck runs fine now. If that doesn't work, I have heard that it could be a bad o-ring on oil pick up tube.

 

[Fless]

I had a similar situation with my 6.0L. I changed oil pressure sensor and screen. Truck runs fine now. If that doesn't work, I have heard that it could be a bad o-ring on oil pick up tube.

Which is why I requested more detail. Without knowing what's been done, we can toss all sorts of suggestions out there. Need more info if help is wanted.

 

[rockola1971]

I suspect that the oil pressure gauge is wrong. If there is one thing a GM engine wont tolerate, its low oil pressure. Youll spin a rod or main bearing or throw a rod right out of the side of the block with low oil pressure. The valvetrain would sound like a sewing machine before it got that bad. Its not uncommon for the before mentioned screen to get plugged up at the oil pressure sending unit. Quick and easy check. Another common problem is incorrectly installed or just old and split oring on the oil pickup tube. Or of course a worn out oil pump.

 

[Tonyrodz]

The NBS don't have screens under the oil pressure sender, that's the NNBS.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[JonnyTahoe]

You have Oil Pressure if you didn't you would know it like Rockola mentioned. If you have ever done a oil change but did not fill your oil filter before you installed it you may have heard a lifter tick for just a few seconds then it goes away when the filter is full of oil and the engine has pressure.

 

[E-Diddy]

Here's my experiences:
I've had a 2002 gmc yukon with 5.3L, made lifter noises when first starting, especially when cold outside, since i got it with 90,000 miles. Oil pressure is over 40 psi at idle, mobil 1 oil changes. Engine runs great.
The 2007 suburban with 5.3L with cylinder deactivation ate 3 qts between oil changes, got an oil warning light, oil was low so topped it off. OIl light still on. Checked oil pressure with mechanical guage, its a pain the first time since at the back of the intake near firewall and is done by feel, pressure was fine, replaced oil pressure sending unit with AC delco and screen below it (use a bent pic to remove, they are cheap so buy two just in case you lose it)...fixed problem...probably got clogged when i ran it low on oil.

 

[S1W99]

I had an '07 with the same problem. I put in a quart of transmission fluid into the oil. Ran it for about 20 mi did a full oil change and never had the problem again. My sweater. Bye Happy for Bye Happy for you

 

[rockola1971]

It is not a good idea to run an engine under load (AKA on the road) with a quart of transmission fluid in the oil. Transmission fluid does not have lubrication properties of oil which is why we put oil in the crankcase and not tranny fluid. Sure in the driveway at idle to free up sticky lifters then drain and complete oil change which ive done on many vehicles but I would never drive a vehicle out on the road with tranny fluid in the crankcase.

 

[CaptainAmerica1]

Oil pressure sensor, or associated wiring.

 

[Leonard country]

Did he replace the camshaft bearings? Does the oil pressure fluctuate at all?

It does drop about 5 pounds when warm

 

[Leonard country]

Which is why I requested more detail. Without knowing what's been done, we can toss all sorts of suggestions out there. Need more info if help is wanted.

They replaced the sending unit but not the screen truck has about 200k on it I ordered screen at pressure sending unit and oil pump and pick tube waiting on them to arrive I tested oil pressure on side of block has about 38 pounds warm I didn't have the correct adapter to test at the top and I wasn't sure what ecm would do if I unhooked gauge sending unit also tried a new cluster seeing as the tac was not working

 

[Fless]

The oil pressure sending unit in your '04 DOES NOT have a screen under it. That's for the AFM engines, which started in the GMT900s.