hello all

i recently rebuilt my engine from top to bottom. finally got her in yesterday and fire her up. had 40 psi of pressure for about 30 sec then to 0. i shut it of restarted and same thing any ideas? oh its 5.2 and has new oil pump and i did prime or i thought i did. but was a week before the install of motor. thanks Jay

 

just thinking out loud.
i wonder if oil pressure sending unit might have gotten damaged during install.
is the sending unit plugged in securely.
could oil filter cause this problem. its the easiest thing to change.
could a foreign object have gotten onto pickup screen or intake tube.
is it full of oil. sorry, had to ask.

 

yes it is full of oil. lol i did my best to clean screen and any other part. i didnt clean the sending unit. but was also wondering if the lifters could have anything to do with it? i used the original roller lifters i had them all apart any the were moving freely? wondering if my new pump is bad from napa auto parts

 

i also filled the oil filter with oil before puting it on

 

i don't think the sending unit is cleanable. its probably a diaphram/spring thing. it might be damaged, but its a little expensive to blindly replace. something like 25-30 bucks. have you got a manual gauge you could toss on just for a second opinion.

i don't think lifters could cause or contribute to pressure problems. they either pump up or they don't, and they either open the valve or they don't, and they either make noise or they don't. not related to oil pressure that i can see.

i doubt the oil pump is bad. its a big hunk of metal housing with metal gears. they usually either work or they don't.
question though - is it a super duper high volume pump or just a standard pump ? i've heard internet stories of high volume pumps outpumping the ability of the oil to drain back down, but i've never seen it and think it might be an old wives tale.

i'd put a new oil filter on just to be doing. who know's whats going on inside it.

 

You took the lifters apart?
If you did, did you keep the parts of each lifter separate or mix them up?

 

its just a standard pump not hv. no when i did lifters i did one at a time to keep each part with one it came from. but i dont know if i have some air lock or what or if there is a way to prime lifters to but they are noisy not insane but you can hear them

 

Well thanks for your input. I think im going to try a new oil gauge first. When i bought the truck i knew it had a rod knock and it was rather loud. I didnt think to pay attention to the oil psi. Also as i said i hear the what sounds like lifter noise in the valve covers but i dont recall that before but it was as i said a loud rod knock. Here is a list of what i did and maybe this helps for other ideas.

1. all new bearings (crank, rod, cam)
2. new oil pump (standard volume)
3. crank spun
4. block line honed
5. new rings
6. reused roller lifters and cam
7. heads (new valve seals, reground, new guides)
8. every gasket was replaced

let me know if anyone knows something im missing. Alot of time and money invested thus far to spin a bearing.