low oil pressure LQ4
 

I just put a LQ4 in my 03 2500HD that had a 5.3 swapped into it before I bought it. I was told.the motor came out of a 03 2500 that was running and driving with no problems with 100k on it. Well I started it up, let it idle for a min or so and shut it down to dowuble xheck theoil level. Oil was fine so I fired it back up and I have low oil pressure coming up on my gauge cluster and the needle on the oil pressure gauge is just barely off 0. When the motor is at 2500rpm theres around 20psi and at 3500rpm its around 40psi. Any ideas? Im thinking about having the oil pump modded to increase the preasure.

Did you have the pan off for any reason? Sometimes the o-ring for the pick up dries up or cracks and it will give you those symptoms.

No I never took the pan off.

I forgot to add that the motor has been sitting for about 4 months if that makes any difference.

Waist sitting without oil in it? That should not make a difference but I'm curious to know how the oil looked when the engine was taken out.

My guess is Oring like said above.

Looks like you got took for a ride, you can try replacing the pump and pickup tube o ring but doubtful it will help any. Once engine warms up you won't have any oil pressure at all if the need is just above 0 now. The cam, main, and rod bearings probably already have damage to them....probably why the engine was removed and put up for sale.

Ya the more I read the more I agree the bearings are probably shot already.

No it had oil in it. The oil didnt look bad at all honestly. No shavingd of any kind that I could see. It looked like it had about 1500 miles or so on it.

Pull the pan and check. Buy some plasti gauge and see what your gap is.