I am on a fresh rebuilt 99 ls1. Drove the car for 3 days and oil pressure was slowly decreasing. Got down to about 10psi hot at idle on a mechanical gauge so pulled the oil pan and front cover off. Replaced oil pump with a new ls6 ported oil pump, and replaced the cam retaining plate and new o-ring. I checked all the bearings and they checked out great, pulled the cam and checked the cam bearings and they were ok.

Got engine all back together and have 10psi at idle still. Bottom end is quiet but the valvetrain is a little noisy. I am stuck and need some ideas. Please help!!

 

Bump any ideas?

 

Does it have the barbell in the rear of the block? Is the oil galley plug installed in the front, to the right of the chain/pump installed? Could still be an o-ring/pumping issue.

 

still seems like a o ring issue to me too. you sure you dident pinch the o ring?

 

Yep usually the pressure will steadily fall if the O-ring is pinched. Did you lube it before installing?

 

Yes the oil barbell is installed. Not sure on the oil galley plug on the front. The previous o-ring was fine and lubed the new really good before installing.

 

Im assuming when you say fresh rebuild you have all new bearings..... rod, main, cam etc. Did a shop do the rebuild?

 

Is your new pump a high volume or high pressure or both?

 

A shop did all the machine work and I assembled it. Yes I put all new bearings in. The oil pump is a brand new gm ls6 ported pump with the normal spring.

 

I even rechecked main and rod bearing clearances with oil pan off and everything is within spec and look great.

 

Man thats a tuff one, Sounds like everything is in check so it shouldnt be runing that low. It couldnt be just be a bad gauge could it? have you tried another gauge. Do mechanical gauges work directly in place of the stock sending units? im sure they do I just dont know. FYI I had an ls1 that wasnt put together right and was getting 10psi when hot and only drove it 200 miles befor looking into it. by that time it had ravished the cam and other bearings. 10psi is to low for that engine. If you say your bearings are good and there is no metal shavings in the oil id say that your oil pressure has to be higher than what its saying.

 

check the oil gallery freeze plug, on the front of the motor under the timing cover, when i finished putting on my oil pump the other day, before i bolted up the timing cover, i decided to crank the engine till oil psi goes up, and it did, while cranking it hit 45 psi. then i looked closely to see if any oil will bleed off from the pick up tube o ring, and i guess mine was ok, no oil. but my dad also made me a girdle to slide over the pick up tube, i think that helped alot, alot safe and secure seal. i also used assembly lube in the pump and that created like a suction for the oil to build psi up faster