Low oil pressure

[ntymd8r]

Pull thennnnn sending unit and check the screen (clean or replace it) Re-install then stick a mechanical oil gauge on it then fire it up to view the reading. Should only need to run it for a few seconds or so.

That would confirm/deny you actually have low OP or no

Pull the sending unit and check the screen (clean or replace it) Re-install then stick a mechanical oil gauge on it then fire it up to view the reading. Should only need to run it for a few seconds or so.

That would confirm/deny you actually have low OP or no

Pull the pressure sender and clean that little orifice out. The smallest particle of gunk can get in there and mess up the readings.

Then I'd remove the oil filter, and blow compressed air or brake cleaner down the pressure sender threaded hole. It goes straight down to the filter, so pressurizing that passage will help blow out the accumulated gunk.

Install cleaned pressure sender without the screen, add new filter and oil, and start engine to see what it says. If it's good, replace new screen & sender, and start up to check for pressure.

You could also thread a pressure gauge into the sender threads, and actually test the issue.

That sounds like a plan. I’ll update when I figure out what the issue was. Thanks!

 

[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.

 

[ntymd8r]

Update.
Drained the oil. No gunk in it. Swirled it around like I was panning for gold and no metal of any kind…wheew!! Unscrewed the oil filter and no gunk there either. Cut it open and it looked to be in order, but it was rather heavy and the filtration pleats where rather hard. Maybe just anxious but it did feel heavier than normal. Don’t know if “maybe” the orange rubber anti-feed back seal had an issue. Seemed like it was not letting anything in or out….sealed up pretty good and very hard to push down through any of the holes, like when try to open a door but you could barely crack it open due to what feels like resistance. *sorry, just trying to explain it!*

Talked to a buddy who used to be a mechanic. Said these model years are prone to have oil pump failures. Gonna be safe on this one and change out the oil pump, water pump, thermostat and all the seals and gaskets for them. Also the oil pan gasket, pick-up tube o-ring and relief valve. Switching to a WIX, too. I’ll update again when I finish.

 

[Geotrash]

Talked to a buddy who used to be a mechanic. Said these model years are prone to have oil pump failures.

Nope. First I've heard that. It's a dead-simple oil pump system. I would sooner suspect a stuck relief valve in the oil pan than a bad pump.

 

[j91z28d1]

Nope. First I've heard that. It's a dead-simple oil pump system. I would sooner suspect a stuck relief valve in the oil pan than a bad pump.

yeah, I'm pretty sure these pumps don't fail and if it did, you've have metal everywhere.

even a stuck bypass valve should build some pressure. to not see any is odd.



I still feel like is the oil pressure sensor. before you pull half truck apart I'd. check the oil pressure at the front of the block right after the pump. there's a test port right there. i believe it's a 16m threaded port, double check that but this cheap kit shows it has 16m size adapter.

https://www.amazon.com/Pressure-Tester-Gauge-Diagnostic-Engine/dp/B0BBGG72JN/ref=asc_df_B0BBGG72JN/?tag=hyprod-20&linkCode=df0&hvadid=652455257749&hvpos=&hvnetw=g&hvrand=14212927646033698544&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9028057&hvtargid=pla-1888426739933&psc=1&gclid=Cj0KCQjwjryjBhD0ARIsAMLvnF8BHk1ECf2Ry3W6gtfSw_ZQMGWb0Kp51jv1V6vX1f7XH4Cf9pmOa_8aAo-tEALw_wcB

if you don't have pressure there you know forsure something has gone wrong.

 

[ntymd8r]

My only issues of it just being the pressure sensor are:

The first time the pressure sensor went bad, there was a check engine light that said so and it ran fine till I replaced it. The oil pressure gauge was dead as a doornail.

This go around, no check engine light, a “low oil pressure, shut off engine” on the display, about 3 psi on the gauge and then the engine shut off itself (fail safe I reckon). So I’m feeling just replace everything….

 

[j91z28d1]

let us know how it goes.

 

[Dustin Jackson]

oil level sensor?

 

[j91z28d1]

oil level sensor?

I don't think these trucks have a level or temp sensor. I'm pretty sure they don't have a oil pressure shut down safety either. but I can't confirm that.

 

[iamdub]

My only issues of it just being the pressure sensor are:

The first time the pressure sensor went bad, there was a check engine light that said so and it ran fine till I replaced it. The oil pressure gauge was dead as a doornail.

This go around, no check engine light, a “low oil pressure, shut off engine” on the display, about 3 psi on the gauge and then the engine shut off itself (fail safe I reckon). So I’m feeling just replace everything….

I don't think these trucks have a level or temp sensor. I'm pretty sure they don't have a oil pressure shut down safety either. but I can't confirm that.

I depends on what fails with the sensor or its circuit. My bud's Tahoe had a failed sensor so it pegged the gauge either at 0 or 80, I don't remember which. AFM didn't engage and I don't recall if he had a code for it or not. His CEL stayed on for an EVAP issue. Engine ran fine.

A friend of his had a NNBS truck that wouldn't start and got one or two codes for the oil pressure and/or sensor. He replaced the sensor and it fired up and ran normally, displaying normal pressure on the gauge.

Maybe it's a dead short versus open circuit thing?

 

[ntymd8r]

UPDATE:

Didn’t feel like troubleshooting one thing after another and increasing time and $$. Did all this in one shot over about 20-25 hours of wrenching $400.00 in parts:

Pulled:

Water pump, thermostat, harmonic balancer, timing cover, oil pump, oil pan, oil relief valve, pick up tube, oil sending sensor and screen, cross member and dropped rack/pinion.

Put on:

New water pump and new gaskets, new thermostat and seal, harmonic balancer, timing cover, new seal and new gasket, new oil pump, oil pan and new gasket, new oil relief valve, oil pick up tube and new o-ring, new oil sending unit and new screen, reinstalled crossmember and rack/pinion and primed the new oil pump through the galley port. Torqued everything to spec. It was an involved job but very rewarding because on start up, she feels and sounds like new. Oil pressure back up to normal and no warning lights. No unusual sounds or leaks after 100 miles so far! Very happy with doing this myself and saving the thousands of dollars it would have cost.

 

[Geotrash]

UPDATE:

Didn’t feel like troubleshooting one thing after another and increasing time and $$. Did all this in one shot over about 20-25 hours of wrenching $400.00 in parts:

Pulled:

Water pump, thermostat, harmonic balancer, timing cover, oil pump, oil pan, oil relief valve, pick up tube, oil sending sensor and screen, cross member and dropped rack/pinion.

Put on:

New water pump and new gaskets, new thermostat and seal, harmonic balancer, timing cover, new seal and new gasket, new oil pump, oil pan and new gasket, new oil relief valve, oil pick up tube and new o-ring, new oil sending unit and new screen, reinstalled crossmember and rack/pinion and primed the new oil pump through the galley port. Torqued everything to spec. It was an involved job but very rewarding because on start up, she feels and sounds like new. Oil pressure back up to normal and no warning lights. No unusual sounds or leaks after 100 miles so far! Very happy with doing this myself and saving the thousands of dollars it would have cost.

AWESOME!!! Well done, and thank you for following up!

 

[Roger906]

Thanks for the replies!

I’ve read a bunch about the screen and sender unit. But I think that’s good. Also pondering the o-ring and oil pump. My added difference is the “shutter and engine self shut off”, which scared the heck out me. It will start again. Just self shuts off after a bit. I’m gonna try it again tomorrow to see what it does. I’ve read oil filter and oil could be culprit, too. Used GM Dexos from day one with AC Delco filters. This last go around I changed to a FRAM and Mobil 1 (Dexos approved) because of inflation. Used this in my 01 Camaro and never had an issue but could that be it??? I’ll update tomorrow with what I find in the filter.

I don't think I've ever heard ANYONE bad mouth Mobil 1. It's a good product.

 

[Roger906]

UPDATE:

Didn’t feel like troubleshooting one thing after another and increasing time and $$. Did all this in one shot over about 20-25 hours of wrenching $400.00 in parts:

Pulled:

Water pump, thermostat, harmonic balancer, timing cover, oil pump, oil pan, oil relief valve, pick up tube, oil sending sensor and screen, cross member and dropped rack/pinion.

Put on:

New water pump and new gaskets, new thermostat and seal, harmonic balancer, timing cover, new seal and new gasket, new oil pump, oil pan and new gasket, new oil relief valve, oil pick up tube and new o-ring, new oil sending unit and new screen, reinstalled crossmember and rack/pinion and primed the new oil pump through the galley port. Torqued everything to spec. It was an involved job but very rewarding because on start up, she feels and sounds like new. Oil pressure back up to normal and no warning lights. No unusual sounds or leaks after 100 miles so far! Very happy with doing this myself and saving the thousands of dollars it would have cost.

Well you pretty much almost covered everything my 250k + 5.3 needed! I don't wanna jinx ya...but exhaust manifold bolts and knock sensors in the intake valley too. Also, I lived in the rust belt....fuel n brake lines.

 

[Roger906]

Change the oil filter to an AC or Wix... The fram filter (or any brand) could have
an issue, be clogged with debris, or failed...
That's where i'd start. $10
I don't care for/ or will ever use a fram oil filter on anything of mine or the others I work on.
But that's my deal.. Others are ok with fram... I've had bad experiences and will never spend $ on
them again.

I had a Fram once that had a pin hole leak from manufacturing defect. I had owned the vehicle awhile n did my own changes regularly. So.....I didn't check oil much, if at all between changes, as the vehicle never used any. And then. One cold dark winter night I was driving looking for the family dog and noticed the idiot light dimly coming on and going out for oil pressure. Found dog. Parked vehicle. Pulled dip stick next day, and nuttin. Grrrr! Looked underneath and on the 318 Mopar it only took a glance to see it was near the filter. Wiped filter added oil n checked for leak. Pencil lead sized weep coming out of the top seam!!!
I wasn't concerned about motor damage cuz I've personally abused these things in several different vehicles and machines! A flicker on the idiot light is about as worrisome as a cloudy day!

 

[Roger906]

That sounds like a plan. I’ll update when I figure out what the issue was. Thanks!

(In my best Beavis and Butthead voice) ^^^^^^ he he ...he..he....he said little orifice...he he he he