Oil pressure switch, screen?

[malmed]

I have searched and can find no definite answer...
Does the 03 Denali 6.0 have a filter under the oil pressure sending unit....?

My oil pressure has been fine, idle at 40 psi, 60 psi under acceleration.
One day about a week ago, suddenly oil pressure down to 10 psi idle and 20 under acceleration.
If I dont keep the idle up, she bing bing bings me, low oil pressure warning.

Now, I really don't believe the oil pressure is low, no indications at all... seems fine, except the warnings....
So, I just figured 200,000 miles, oil pressure sending unit...
Swapped it for a new one today...
NO change at all.

I run an AC Delco oil filter and Mobil 1 10w30.

My son says on his 07 truck, he changed his AC Delco and the oil pressure went back up to normal...?
I don't buy that, but, ?

So, I went and did an oil and filter change today, to a WIX synthetic filter... NO change.

All I can guess is there IS a filter under the oil pressure sending unit, and it is dirty... or my oil pump suddenly went bad, which really does not seem likely to me, slow progression I could see, overnight? no way....

 

[Rocket Man]

Just the NNBS have a filter there AFAIK. Not the NBS. It might be the o-ring on the oil pump pickup tube; they've been known to crack and oil pressure goes down since suction is lost. You can use a manual pressure gauge to test actual pressure. I haven't done it but I know there's a way.

 

[Rocket Man]

Just the NNBS have a filter there AFAIK. Not the NBS. It might be the o-ring on the oil pump pickup tube; they've been known to crack and oil pressure goes down since suction is lost. You can use a manual pressure gauge to test actual pressure. I haven't done it but I know there's a way.

 

[malmed]

After further reading here: https://www.motor.com/magazine-summary/trouble-shooter-jan-2017-low-oil-pressure-vortec/ I am convinced my oil pump pressure relief valve is stuck open... recent cold startup, high rev to warm her up fast, pressure hit 70, relief valve opened and stuck.... Sooooo, any way to make it move back into place? to close a stuck open valve without tearing her apart?

 

[SnowDrifter]

No screen. It wasn't implemented until AFM I believe. Or it might be the NNBS. Can't remember.

You need to remove your pickup tube to get to the pump if you believe that to be the issue. However I'd question what causes the thing to stick. It's an oiling system, everything is lubricated. The channel the thing sits in is machined and smooth. Under normal operation, it shouldn't stick period. So that means something made it stick. Sludge, debris, etc. The mind boggles.

If it's sludge, you could potentially run a diesel/kerosene mixture. But I really, really wouldn't advise that option. To be frank, I wouldn't run your vehicle at all. You'll toast your engine in far less time than you think.

If your oil pump gears cracked, there would be no warning or lead up.

Another option is you could have incurred a failure in your oil pan gasket. It has some passages cut into it which are sealed off by the gasket. If that suffers a failure and begins leaking internally, you'll end up with low oil pressure.

Quick check to see if it's pickup tube related or something else is to overfill your oil. No. Seriously. Bring the oil level up to the level of your oil pump pickup or just a hair past it, jack the ass end of the car up in the air, and give it a start. Do NOT drive or run the vehicle for longer than a few seconds in this condition. You'll be grossly overfilled. The crank is be whipping up the oil, splashing large amounts into your cylinder walls, oil sitting on your crank seals, etc etc. Fine for a quick diagnostic. Not fine to drive or operate for longer than just a moment.

Admittedly I'm not sure how much oil you'd need to add over fill, whether it's 2 quarts or 8. Theoretically you could remove your dipstick tube and fill the thing like a differential - until it dribbles out.


Don't forget, in all of this, to check pressure with a mechanical gauge. A new oil pressure sender doesn't mean it's good. And it doesn't mean wiring for the thing is fine.

 

[malmed]

While I agree the new oil sending unit does not guarantee it, but since the new and the old read almost identical, that's a pretty sure indication it is NOT a sending unit problem... broken gear in the oil pump is an idea I have not thought of as a reason it happened suddenly... I'm thinking about a heavy dose of marvels mystery oil or seafoam, and see if it free's up the stuck relief valve...? I have filled her as full on the stick as she can go, and I am going to find a very steep hill today and see if the oil pressure comes to normal to test the o-ring... It makes some sense to me about the pressure relief valve sticking. I work second shift, we have had some very cold nights, I walk out start my truck, and was really kinda amazed at how high my oil pressure would go nailing it to 'warm her up fast" I know I have seen 70 psi on the gage.... so, I pushed her hard, with good clean oil, relief valve opened, and stuck open... very believable with my symptomes... or it could be a filter under the sending unit, if it has one... but it looks like it does not from what people say... Thanks for the input... still really just trying to figure out what's wrong, before diving in.... broken gear in oil pump, could be....

 

[malmed]

I got her as full of oil as I could, and still feel it was ok to drive, found the steepest hill I could find, and it made no difference at all....

My gut at this point is, that the pressure relief valve is stuck, or the oil pump broke a tooth or something, but I have put about 100 miles on it since this problem started.... so... ?

 

[Rocket Man]

I doubt there is a problem with the oil pump, they last almost forever on the LS engines. Pressure relief valve possibly. I would test the pressure with a mechanical gauge and if it's still low, either drive it as is or put in a new oil pump to correct the relief valve issue. You can put in a new pump without dropping the pan. The hardest part I found was pulling the harmonic balancer but there's a YT video I can direct you to that makes it pretty easy.

 

[malmed]

Sure, link me to it, I guess a new oil pump is in order, I have watched a couple YT vids on it, seems easy enough, hard part is harmonic balances, and if I break the damn bolt.... and the screw for the pickup tube, I guess fishing line and a magnet are the answer there.... While I have her apart, I guess new water pump, lower hose, and what else? Timing chain seems a waste to change as they rarely go bad....

 

[Rocket Man]

Here’s the link. As you’ll see in the video, the Chrysler puller works perfectly. Don’t even try any other method, this works so easy you’ll be amazed. As for the bolt for the pickup tube, stuff a rag in the hole below so it can’t fall into the pan. At 200k I’d do the chain, they do stretch. No need for the water pump, it can be done any time. This way you’ll have taken care of the o-ring too since the oil pump comes with a new one and the pickup tube will be disconnected. Also I recommend an ARP harmonic balancer bolt, easier to install.