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Hey guys, i'm looking for a few opinions before I start taking things apart or wasting too much more time. I work at a small independent repair facility / used car lot and this is an auction bought vehicle. The symptom is low oil pressure displayed on the gage ( needle barely moves from 0 maybe 1/8 ").. "low oil pressure shut engine off" is displayed in the driver information center and the red oil pressure light is illuminated. The engine appears to be not that old. The engine sounds very good, no noises whatsoever. I first changed the engine oil and filter using pf63 filter with no change. Next I changed the oil sender and the VLOM filter screen with no change. I removed the screen completely with no change. Next I measured engine oil pressure at the engine oil filter using the EN-47971 filter adapter. I measured approximately 24 p.s.i. with the engine warm at idle. With the engine at 2500 r.p.m. the oil pressure measured approximately 58 p.s.i. Next I measured oil pressure at the oil pressure sensor location behind the intake manifold and measured approximately 9 p.s.i. at idle and 32 p.s.i. at 2500 r.p.m. I bypassed the engine oil cooler with a 2 bolt oil pan cover from a different engine with no change. I also stuck a camera as far as I could down the oil pressure sensor hole and didn't see anything revealing. I'm sort of wondering the next easiest step? Or if this engine is just no good? I don't have a ton of experience troubleshooting low engine oil pressure complaints outside of the common pickup tube o ring, sensor and screen sort of issues. I'm thinking about removing the VLOM, engine oil pan and Maybe the rear main cover unless the tests I performed just prove the engine needs to be overhauled / replaced. Thanks.
That's a weird one. Minimum oil pressure is 24psi @ 1000rpm hot.
The measurement at the filter housing is well within spec. Low oil pressure at the pressure sender, but good pressure at the filter would indicate a problem with the screen, but you removed it. I'm very curious to see where you end up with this one
IMO, with the oil pressure readings you posted, you're likely looking at worn camshaft bearings. It's somewhat common on this generation of LS engine. 5.3's, 6.0's and 6.2's. That'd account for your decent-ish oil pressure at the oil filter, but definitely low pressure at the pressure sensor. The camshaft is between the two on the oiling circuit.
As far as your next move, you can pull the oil pan and do a visual inspection inspection of the bearings to see if you can find one that's clearly overheated. But, even if you don't see clear signs of overheating, that doesn't mean they're not worn out. You could also use a engine oil primer to feed oil into the pressure sensor port and see which bearing gushes out. If you do find a bad bearing, you can replace camshaft bearings.
But, if I'm being honest, I think that's a big waste of time/money. How many miles are on this engine? If it's over 100,000, I think you're better off with a new or reman long block. These engines have TONS of expensive problems. Lifters collapsing, oil consumption, oil fouled spark plugs, oil leaks, like that.
Did it come in with oil on the dipstick? Was there any metal in an oil sample? If you have the old oil filter around, you can cut it open and see how many shiny bits are hanging around in the bottom of the filter.
