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NO OIL PRESSURE!! Help quick please

1736 Views 10 Replies 7 Participants Last post by  uniquecarriers
I just rebuilt an 05 cummins due to a dropped valve seat. I replaced all the piston rings, one piston, new head, all new bearings on everything by the customers orders. I got everything back together and started it. It showed oil pressure on the gauge but then dropped to zero. So i hooked a mechanical guage up and still had no pressure. So i thought maybe the mechanical is bad....i took the line off the housing and started it....NOTHING came out.. I then replaced the oil filter thinking it was a bad oil filter even though it was brand new...still didnt cure the problem... Does anyone have any ideas??? I need to have the truck done as soon as possible as college ended last week and im still working on it at the college. Thanks guys!
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Bump. Any ideas guys?

Thanks for the bump. Anyone??? anything???
I am not familiar with how the suction tube attaches to the oil pump, but if it is loose it would suck air and cause problems. Also the relief valve could be stuck open. Just thoughts off the top of my head.
I torqued the tube and im positive i put the gasket on the suction tube so im ruling that out. That was the first thing i thought of but it couldnt be. I also took the cap off the relief valve and pulled the spring and valve out and it seemed fine. it slid in and out pretty smooth. The engine didnt have any oil issues before the rebuild that i know of since there werent any spun bearings or cooked bearings but do you think it could be a bad pump??? it is the original pump but maybe it was almost done for and since it lost its prime it doesnt quite have enough suction to reprime??? Ive tryed forcing oil into the oil filter housing to get it to prime but no luck. Thanks up for ANY ideas
check out this thread, i listed what the manual says about low oil pressure and the lube system operation.
any chance there is sludge in the oil pan? could be clogging the pump. i had that problem with a chevy with a 350 in it that only had 60000 miles.
Nah i doubt it. I super cleaned everything including the block. its was completely torn down and thinking its the oil pump but i dont know. I need some more opinions before i tear it back apart because i really dont want to pull the front cover to find nothing wrong and then have to pull the pan. or the other way around.
Did you fill the filter with oil before you installed it? It holds about a quart and if the pressure sensor is after the filter (not sure) you will read zero until the filter fills.
Priming a new engine can be really fun. With gassers you can sometimes access the oil pump with an electric drill and prime it without running the engine. Hmm on a gas vehicle you would remove the coil wire and crank it over to prime. Lastly I would take the oil pump off take it apart and pack it with bearing grease. It's alot of oil to kill, but it will be primed. The grease provides a nice air tight seal to allow a draw. Make sure there are no leaks anywhere air could get in. Good luck.
Check the oil pump, I had a 05 engine rebuilt at a shop and it to had oil presure the first 1-2 hours then lost presure and toost # 6 rod out the side of the block.
When we dismantled the engine we found the pump had a crack in the casting of the pump and the drive gear brooken away. Don't know if it was stressed when installed or overtightened or maybe a casting flaw.
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