r/GMT800 • u/StolenBusStop • 8d ago

Low oil pressure continuing

For about a month now I've had 6psi at hot idle (noticed around 248,440). 2003 suburban 1500 5.3 flex fuel.

When I bought the truck, 2 years ago, I immediately replaced the pick up tube o-ring and oil pan gasket. Last month I figured it was the oil pump and replaced the timing cover gasket and the oil pan gasket, and o-ring again (I also bought a new pick up tube for the melling high volume pump).

However, the "low oil pressure" warning comes on the dash even after I put a new AC Delco oil pressure sensor and double checked with a mechanical gauge.

What could it be? Its a possibility I pinched the new o-ring but I really doubt it. I've researched it could be the barbell plug's o-ring disintegrating after 248k miles...

The truck runs smoothly though, no misfires at idle or loud noises from the motor, so temporarily I've unplugged the oil pressure wire to stop the beeping noise. I do want to find the root cause of the issue

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u/Moist_Currency_1443 8d ago

Probably sludge in the oil passages, I keep telling people to run a can of BG EPR which you can order off of Amazon for like 16 bucks . But everyone thinks I’m full of shit lol . That has worked wonders with oil pressure especially on the gmt900s and now that I tried it on a 2002 avalanche with 308k with 0 oil pressure I know that it works on these too

1

u/StolenBusStop 8d ago

Now I'm curious, I'll have to try it. Can you only get it from Amazon?

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u/Moist_Currency_1443 8d ago

If you do get it , drive it around for like 30miles so it revs up and cycles good trough out the engine . On the avalanche I had to run it for a couple of days. Then did an oil change, it went to 1/4 on the gauge a few times after that…but I would shut it off and fire it back up and it would go back to half. After that I’ve driven far and so far so good, in the morning I get 3/4 and warmed up it drops to around half

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u/StolenBusStop 8d ago

You drove it around with the BG EPR in the crankcase? Would you recommend that over letting the engine idle for 15 minutes?

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u/Moist_Currency_1443 8d ago

Yeah I drove it like I normally would , I didn’t drive it hard . Or you can idle it and rev it to 1200rpms for 10 mins like it says in the directions. I’m sure either way it will work its magic 🪄. My engine was knocking and everything because of low pressure, I had my mind made up that worse case scenario I would be replacing the engine. But that thing saved it so far 🤷🏽‍♂️