We pulled this 2003 Hummer H2 6.0L into our bay. Had a knocking noise. We found the noise which was the connecting rod bearings so we replaced them. For some reason a couple still have play & still giving the knocking noise. Also our oil pressure went from normal to low oil pressure, but if we give it gas it takes the oil pressure back up. We are looking at the Oil Pressure Switch on the back side of the motor being bad, so we are going to replace it.

If anyone knows of anything else that could cause either of these issues please feel free to comment & let us know.

Thank you for everyone's help

 

replace the oil pickup O ring. it is a know issue on LS /LQ based engines for the symptom you described (working before and now not). it might have gotten disturbed when working in the area they turn square as they age when they should be round. but it can also be the oil pressure relief spring. as for oil pressure try getting a physical reading directly from the engine block with a oil pressure gauge as the dash cluster might have bad gauge stepper motors and not read properly.

 

I had this same issue after my mechanic replaced the dip stick tube and broke it off in the block. I guess when he was fighting to get the remaining piece out he dropped some metal in to the pan it then got sucked up into the pump. 3 seafoam and oil changes still no difference. I had the exact same issue. At idle 0 pressure. If i gave it a shot of gas the pressure would build as normal. Let off back to 0.

Unfortunately, you are looking at a new oil pump which is located in the timing cover. I asked for the old one so i could take it apart and see where it failed. I found a small burr on the piston that would hold the piston in place and close off the oil port. A shot of gas would free it. Let off and it would lodge itself again.

Hope this helps, good luck