A friend and I are trying to track down a no oil pressure problem on his new bottom end. He blew his old 5.3 and had it rebuilt with new pistons, bearings, and oil pump.

Now the problem is that it cranks over without a problem but we don't see any oil pressure. The new engine hasnt been fired because of this problem and we crank it over by hand to see if the top end can get oil but there's not a drop. Havent had a chance to work on it because of work so he took it over to a shop, they replaced the oil pump and threw in some new pushrods as well. Today my buddy called and said there's still no oil.

Any ideas?

 

pickup tube o-ring, or the dumbell plug at the back of the engine generally 2 things people forget

 

These motors don't prime the way a gen I motor does. I jacked the rear of my car up as far as I could, which completely submersed the oil pump. After cranking it over for about 15 seconds it built up pressure. Some other people rig up fittings to put in the front of the block, whatever works. If you cant "prime" the system then I would look at the pick up tube o ring or the dumbell. Good luck!!

 

I thought i had an oil pressure problem when my engine shut down on the street and had to tow my car home!! My engine was cranking all my gauges were moving except my oil pressure gauge so i thought my pump or something else went bad!! I check the wire to the pressure sensor but nothing!! I didn't want to get my self too much into it and start taking it apart! so i did a basic test fuel and spark!! And found out that my fuel pump went bad no pressure!! when i finished installing the fuel pump my car started right up and then my oil pressure gauge started working!! So WALA!! I discover that the oil pressure gauge doesn't work when the engine is cranking only when running!! So i don't think you have a problem!!!

 

^^ this. You won't even see oil pressure on first startup for 3-4 seconds. If you don't see it after 5 seconds, shut it down and look for a mechanical issue.

oh.. and make sure it has oil in it. Don't laugh, I had a guy who asked me a ton of oil pressure questions and ended up forgetting to put oil in.

 

Double checked the oil pump o-ring but what's that dumbell plug your talking about? I didnt have a chance to take the bottom end apart when it went south so I'm not sure what part it is exactly. While back I remember seeing something odd taken out of the block, a plastic part that I though was rather odd.

The shop is having trouble tracking the issue, if worse comes to worse I'm gonna take some time off to check it out myself which I don't want LMAO!

 

Plastic part that looks like a dumbell that goes in the rear driver side of the motor.. Has an o-ring on one side of it..

 

This (see pic) & if it was removed (plastic part) you will not get pressure. Also, don't expect oil to the valvetrain as an indicator, if it's a pre-04 block. Rear oil passage is restrictive & it takes time to fill lifters & pushrods becasue of the restrictive rear oil passage. Post 04 or LS6 block, rear oil passage is much larger & eliminates the slow valvetrain oiling.

 

The block is off an '08 silverado 5.3 (aluminum). Yeah, I've seen that part before but i'm not sure whether or not the machine shop threw it back in. After a long afternoon, the oil still wont come up to the topend when the engine was cranked over. I have a feeling I'm gonna have to head over there and take the thing apart starting with that oil pump and moving over to that dumbell.

Gonna have a talk with the shop and get more info, maybe they can take care of it before I head over this weekend.