LMG Low Oil Pressure
07-07-2024, 02:05 PM
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LMG Low Oil Pressure Hello everyone,
I've got a 2012 Suburban LMG 5.3 with 198k on it. Bought it with 192k on it with a worn cam. Sent the engine out for rebuild (new rings, cam and crank bearings), bought a BTR AFM, DOD, and VVT delete kit while the engine was being looked through. New oil pump, gaskets, etc. Engine got an L92 cam, Non-dod valley plate, new oil pump (GM L92 pump), new pickup o-ring, new cam retainer plate. Used some 5w-30 driven oil for around 500 miles, changed the oil and filter after that interval to a full synthetic. Around 5k miles later, changed the oil and filter again. The vehicle has been running decently for the past 5k miles, displaying 60 psi of pressure. About a month ago, after getting the vehicle up to operating temp on my way home, I heard a slight knocking noise from the engine and the oil pressure had dropped significantly, both while at idle (around 40 on the gauge, which I now believe is closer to 0). While driving any speed, the pressure will maintain what appears to be normal pressure at 60 PSI. Recently, I changed the oil and oil filter just in case the ACDelco filter I had installed was somehow damaged, which did not fix the issue. Not too familiar with how used oil should look, but it certainly wasn't glittery. Is there anywhere I should be looking as the culprit? I've read that the LMG engines came with a separate oil pressure relief valve mounted inside of the oil pan that is prone to failure. This is something I was unaware of at the time of rebuilding the engine. Furthermore, there is a slight amount of oil coming out of the cover plate area. This engine doesn't consume or leak any significant amount of oil in the 5k oil change interval I performed on this. The only other thought I had was for the oil diverter barbell, but it's my understanding that I would have 0 pressure at all times if that were missing. While anything can happen, I find it hard to believe that a brand new oil pump would fail or the pressure relief valve internal to the pump would stick open.
I've got a 2012 Suburban LMG 5.3 with 198k on it. Bought it with 192k on it with a worn cam. Sent the engine out for rebuild (new rings, cam and crank bearings), bought a BTR AFM, DOD, and VVT delete kit while the engine was being looked through. New oil pump, gaskets, etc. Engine got an L92 cam, Non-dod valley plate, new oil pump (GM L92 pump), new pickup o-ring, new cam retainer plate. Used some 5w-30 driven oil for around 500 miles, changed the oil and filter after that interval to a full synthetic. Around 5k miles later, changed the oil and filter again. The vehicle has been running decently for the past 5k miles, displaying 60 psi of pressure. About a month ago, after getting the vehicle up to operating temp on my way home, I heard a slight knocking noise from the engine and the oil pressure had dropped significantly, both while at idle (around 40 on the gauge, which I now believe is closer to 0). While driving any speed, the pressure will maintain what appears to be normal pressure at 60 PSI. Recently, I changed the oil and oil filter just in case the ACDelco filter I had installed was somehow damaged, which did not fix the issue. Not too familiar with how used oil should look, but it certainly wasn't glittery. Is there anywhere I should be looking as the culprit? I've read that the LMG engines came with a separate oil pressure relief valve mounted inside of the oil pan that is prone to failure. This is something I was unaware of at the time of rebuilding the engine. Furthermore, there is a slight amount of oil coming out of the cover plate area. This engine doesn't consume or leak any significant amount of oil in the 5k oil change interval I performed on this. The only other thought I had was for the oil diverter barbell, but it's my understanding that I would have 0 pressure at all times if that were missing. While anything can happen, I find it hard to believe that a brand new oil pump would fail or the pressure relief valve internal to the pump would stick open.
