Oil System Priming

I just got done installing my junkyard 4.0L. I had the head done, new gaskets, oil pan, rear main, ect.... Im trying to prime the Oil pump by hand before i fire it up. I spun the pump for a while and have yet to see any oil come out of the pushrods/rockers. Im spinning the oil pump clockwise with my air ratchet. Any ideas?

If the pump is completey dry it will take a while. Keep at it.

I always fill the pump with vasoline before installing. It creates a near instant suction.

Frank Z said:

If the pump is completey dry it will take a while. Keep at it.

I always fill the pump with vasoline before installing. It creates a near instant suction.

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After reading all the "Oil Priming" threads on various forums, I wish i would have known about the vasoline trick when i had the pan off.


I spent maybe 1.5-2 min spinning, but i wasnt timing it and it felt like an eternity. Clockwise is correct then? Would filling the oil filter manually help in this situation?

Yes clockwise, filling the oil filter....can't hurt.

Try using a drill.

Sounds good, i'll give 'er a try in the morning!!

Remove the sump, remove the pump cover, fill all cavities with Vaseline or with chassis grease. Even engine assembly lube will work.

Priming an oil pump "dry" is a 30/70 shot at best, and the odds are not in your favour...

Packing the pump will let it pick up a prime in the first few seconds, and then you spin the pump until you maintain pressure for at least one full minute. I typically prime with a mechanical gage screwed in where the electrical sensor goes, then remove it and install the sensor once I'm done priming. I'm usually happy to see 25-30psig @ 2500rpm (drill speed,) and then everything's just ducky.

Any chance of this might work?

-- Pull the oil filter and squirt or pour some oil into the passages on engine and then return filter and 'drill' it. (trying to go around the filter antidrainback valve. should be 'downhill' into pump.)

Good Luck,
Orange

orange said:

Any chance of this might work?

-- Pull the oil filter and squirt or pour some oil into the passages on engine and then return filter and 'drill' it. (trying to go around the filter antidrainback valve. should be 'downhill' into pump.)

Good Luck,
Orange

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Hm. Try turning the oil pump backwards slowly while you're doing it, so you fill all the spaces in between the gears and housing.

Seriously, I've never actually had an oil pump prime that wasn't packed with grease/Vaseline first. I've heard that it can work without it, but I've never had it happen in the last thirty years. Probably just my luck.

Good advice 5-90, thanks again!