Oil pressure dropping

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Rocket Man

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Mine has always read 40-45 at idle, 55-60 when driving. I've heard above 15-20 at idle is fine.
 

sam05

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Here is my oil pressure AFTER repair at 1000 RPM and at idle...Shop says I should only check it at 1000 RPM because my idle is too low.
1000 RMP Oil Pressure.jpg idle oil pressure.jpg
 

Rocket Man

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Idle looks close to normal- mines about 700 but yours looks to be 500 according to your tach? I forgot that after a new pump my pressure is about 60 at idle. Ask them if they checked pressure with a manual gauge so you can rule out a problem with your gauge. Is it possible that someone has replaced stepper motors or your gauge face and didn’t get the pointers back on right so your gauges are off? If you have access to a cluster from a 2000-2006 Tahiti/suburban/Tahoe it pickup you can swap them for a minute to compare the readings on the gauges. Otherwise if it’s not knocking and there’s no warnings you should be ok.
Edit: I just noticed your volt gauge appears to be off so my theory of someone messing with the pointers seems more and more possible.

C8472D8C-CC40-4BA1-9BB0-3EBD1575A755.jpeg
 

sam05

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Thank you. I was thinking about stepper motors. Would an extra/aftermarket oil pressure gauge make sense? Then I could monitor it. I will be going back to the shop for him to recheck it on his actual gauge.
 
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Musicars

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Here is my oil pressure AFTER repair at 1000 RPM and at idle...Shop says I should only check it at 1000 RPM because my idle is too low.
View attachment 199139 View attachment 199140
Your gauge is reading exactly the same as mine does right now after I replaced my o-ring, both at idle and at 1000 RPM. It's a little higher when cold. It used to sit at around 40 psi. I have not done the pump yet.

Mine was lower before the o-ring and triggering the "Low Oil Pressure" warning. Is this current reading the same reading you were getting before the repairs or was it lower before the repairs?
 

sam05

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This is very close to before repairs but when driving it now goes up around 35 if the RPMs are up. Prior to repairs it was not getting that high.

The shop is telling me that the rear main seal can be problematic for oil pressure but I had that changed last month with my flex plate replacement so it shouldn't be a problem. I'm waiting for the transmission shop to call back with the part numbers they put on for the rear main seal...hopefully they did both pieces and not just the gasket!

My other lead(s) have to do with Rocket Man's suggestions about stepper motors above...I'm trying to find out if my bluetooth ODBII reader will give me an oil pressure reading on my app...if not, I'll have to get an external gauge to try.
 

Rocket Man

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I looked with my Tech II and it doesn't show actual oil pressure so I'm thinking it isn't available through the system although I don't know why it wouldn't be. It shows whether the oil level switch is working and whether the low oil pressure has been triggered so I dunno. As far as aftermarket oil gauge, I'd suggest just getting the dash one calibrated if it's off. You could rent or buy a mechanical gauge and see what the pressure is at idle and 1000 rpm and set your cluster needle so it's correct. There's a way for an instrument cluster repair place to calibrate the gauges so that's another possibility if it's off.
 

sam05

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I can't find oil pressure as an option in my app (or an additional app I tried) just like you said. I picked up a mechanical oil pressure gauge but ran out of time this weekend before I could put it on the truck to test my actual pressure. Maybe tomorrow it will happen.
 
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Musicars

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Just reporting back with were I am at since the start of this thread. Finally got the new oil pump in. Started it up and the pressure is right were it was when I started this pain in the rear project.

Drove around and made notes. Highway from 55 mph to 70 mph the oil pressure sits steady at 30 psi. Driving around town it runs 20 psi to 25 psi. It idles with 10 psi. Last night I shut it off and restarted and the oil pressure was just below 10 psi. I'll have to see what happens today.

Very frustrated and not sure what to do from here out. Still find it weird the way this dropped pressure over just a few days. In the past worn bearings seem to gradually get to this point. There were some tiny flakes of metal in the pan but I would have expected more unless they were trapped in the filter. Even more frustarting is that the last couple of times I have gone to mechanics I have found them to not be reliable so I'm not even sure who to take it to. Sounds like keeping this truck is going to be expensive.
 

swathdiver

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Just reporting back with were I am at since the start of this thread. Finally got the new oil pump in. Started it up and the pressure is right were it was when I started this pain in the rear project.

Drove around and made notes. Highway from 55 mph to 70 mph the oil pressure sits steady at 30 psi. Driving around town it runs 20 psi to 25 psi. It idles with 10 psi. Last night I shut it off and restarted and the oil pressure was just below 10 psi. I'll have to see what happens today.

Very frustrated and not sure what to do from here out. Still find it weird the way this dropped pressure over just a few days. In the past worn bearings seem to gradually get to this point. There were some tiny flakes of metal in the pan but I would have expected more unless they were trapped in the filter. Even more frustarting is that the last couple of times I have gone to mechanics I have found them to not be reliable so I'm not even sure who to take it to. Sounds like keeping this truck is going to be expensive.

Tiny flakes is a sign that something is up and not right Joel. Have you sent the oil out to be analyzed? They may be able to decipher what kind of material is in the oil and whence it came from. Seems to me though, after all the work you've done, that it's time to put new bearings in it; time to freshen up the bottom end.
 

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