I’m a long time lurker but first time poster. I’ve read through all the low oil pressure posts, but didn’t find one about the issues I have with mine.
Quick backstory first: When I got my avalanche, the previous owner removed the check engine light and jacked around with a lot of other stuff. I’m not sure what else they may have torn into, but I don’t think they kept up with regular maintenance.
2005 1500ls 2WD with the 5.3l.
On a cold start, oil pressure is around 42psi and stays there until it gets up to temp then slowly starts going down until the low oil pressure message appears on the dash. I’ve verified it with a mechanical gauge and it does, in fact, drop. Revving the engine will make it climb to a max of around 34psi. I also get a DTC for the knock sensor in bank 2, but that could very well be due to it running when the pressure is low. There is no loss of power, so I wouldn’t think it would be the cam bearings. Rod bearings have a clearance < 0.005” and main bearings are also well within spec (except #5).
Yesterday when at temp pressure tanked as usual, but when I revved the engine to about 2k to build pressure, it remained around 20psi at idle for a good 20 minutes. I shut it off then started it again around 10 minutes later and it tanked to around 5psi again. Couldn’t get it to stay at 20psi again like it did earlier.
I have tried the following to no avail:
Replaced o-ring on the pick up tube
Replaced oil pump
Replaced rod bearings (journals looked perfect, so did a roll in)
Replaced main bearings (all except #5 because I didn’t want to drop the transmission; journals looked perfect so did a roll in)
Replaced timing chain and gears (since I had to pull the timing cover to replace oil pump figured I might as well while I’m in there)
Added 1 quart of Lucas oil and filled the rest of the way with 5w40
Is there anything else that I haven’t thought of? At this point replacing the engine is the only thing I can think of. It has around 204k on the cluster, but I think someone swapped it because carfax reports 240k.
Quick backstory first: When I got my avalanche, the previous owner removed the check engine light and jacked around with a lot of other stuff. I’m not sure what else they may have torn into, but I don’t think they kept up with regular maintenance.
2005 1500ls 2WD with the 5.3l.
On a cold start, oil pressure is around 42psi and stays there until it gets up to temp then slowly starts going down until the low oil pressure message appears on the dash. I’ve verified it with a mechanical gauge and it does, in fact, drop. Revving the engine will make it climb to a max of around 34psi. I also get a DTC for the knock sensor in bank 2, but that could very well be due to it running when the pressure is low. There is no loss of power, so I wouldn’t think it would be the cam bearings. Rod bearings have a clearance < 0.005” and main bearings are also well within spec (except #5).
Yesterday when at temp pressure tanked as usual, but when I revved the engine to about 2k to build pressure, it remained around 20psi at idle for a good 20 minutes. I shut it off then started it again around 10 minutes later and it tanked to around 5psi again. Couldn’t get it to stay at 20psi again like it did earlier.
I have tried the following to no avail:
Replaced o-ring on the pick up tube
Replaced oil pump
Replaced rod bearings (journals looked perfect, so did a roll in)
Replaced main bearings (all except #5 because I didn’t want to drop the transmission; journals looked perfect so did a roll in)
Replaced timing chain and gears (since I had to pull the timing cover to replace oil pump figured I might as well while I’m in there)
Added 1 quart of Lucas oil and filled the rest of the way with 5w40
Is there anything else that I haven’t thought of? At this point replacing the engine is the only thing I can think of. It has around 204k on the cluster, but I think someone swapped it because carfax reports 240k.