Alright, so i rebuilt my engine last week and it runs great but whenever the engine is under load, it loses all oil pressure.... I thought it may have been the sending unit so i replaced it but that changed nothing. I took the oil pan off and found that the oil pickup was clogged with **** (the little screen was) I cleaned the screen and put the oil pump back into the truck and then put the oil pan back....oil back in it, started it up and sure enough...NO OIL what so ever!!!! It worked before and now it doesn't but it makes no sense to me...I didn't take apart the internals so i don't understand why it no longer works....Any ideas? or should i just replace the damn thing....
Thanks for your hlep

 

so now its consistantly at 0 PSI? i heard if the oil pump is off by just a very small amount it can crack it. so it needs to be igned up perfectly.

 

How extensive of a rebuild was it? New oil pump?

 

what was the **** on the screen ?
is the pickup tube lined up correctly ?
did you prime the pump ?
did you bench test it to see if it worked ?
was the shaft from the distributor ok ?
did you use a new gasket ?
oil pumps not cracked is it ?

 

the rebuild did NOT include a new oil pump i did however take the original one apart and cleaned it out really nice. I've read that they don't go out for the most part so i didn't replace it. I did not prime the oil pump because that involves taking out the distributor and the shaft that goes down in there...way too complicated when the engine is in the truck...I did line the pick up back up to where it belongs....

 

i'd pull it back out and bench test it.
you can stick a screwdriver down in the hole where the dist shaft goes and spin it by hand. or, hook up a drill to it. then stick the pickup tube in a bucket of oil and give it a spin.

prime it by pouring oil in the top of the pump. if you don't do that, it can air lock.... that's probably what's wrong.

more importantly, what was the **** on the screen ?

 

I recently read somewhere that after a rebuild,...the oil pick up must be installed properly or this scenario of yours will happen. You need to check for the EXACT pan clearance to pick-up screen, mark it, and give it a weld to hold it in, PLUS the tubes have a knack of leaking by the grommet where the pick-up tube is inserted. That's why you need to weld it in, or you'll drive yourself "CRAZY" analyzing "0" p.s.i. oil pressure,...try it out, guaranteed to fix it. (p.s.: also make sure your bearings are up to snuff,..older engines..try some STP or Lucas additive to help pressure problems). *also,..can't hurt to use a Melling high volume oil pump either.

 

the **** was little tiny pieces of metal...probably from the screwed up bearings that were previously installed.

 

reckon any of that ****s up in the oil pump ?
i might replace it.
also just for fun, with pump and filter and sending unit removed, i might blow some compressed air back down the sending unit hole.

i've never welded in a pickup tube. i guess you could, but its tapered pipe threads. i just put teflon tape on the threads and tighten the **** out of it. make sure it stops in the proper position. sometimes it takes a couple of tries with the teflon tape to get the right amount.

 

If you have to get a new pump get a new pick up also.Not that much more $$