HELP! No oil pressure after new pump

Just installed a new oil pump and rear main seal.
I checked everthing twice
filled it with oil. 6qt
Checked the dipstick.
Started engine
NO OIL PRESSURE!!
What did I miss??? :banghead:

It´s recommended to pack the pump with vasiline, before assembly, helps it to suck better. Make darned sure the pickup didn´t fall off or get knocked loose during assembly. I´d guess the pump cover or gasket, could be a possibility. If the prime leaks out of the pump or the pump sucks air, it won´t work well.
I´ve never tried to pre oil a 4.0 motor, with a drill and sloted rod. Someone else may have some imput.

Pre oiling is the only way. It takes a minute to get the oil up into the pump but its better to do it while the crank isn't turning than when it is.

I just read through my FSM, it said oil can be pumped into the oil pressure sender opening or the motor can be cranked, with the igniton disconnected, until pressure comes up. Recommend a mechanic gauge be used, during the engne cranking methode, the pressure probably being to low to register on the electrical gauge.

Thanks.
My FSM didn't mention vaseline in the pump. However I did read that in a post when I searched. I did put some in but was hesitant to put to much I guess I didn't get a good prime. I will try the other methods. If no luck I'll drop the pan again. Thanks for responding if anyone else has input I'll take all the advice I can get.
Thanks

Pull the distributor, chuck up a blade from a big flat screwdriver. spin it up with the key on until you get ample pressure on the gage or the light goes out. Replace distributor.

I'd also do an oil change/filter again soon after a dry start.

There is an easier way. Just start it up and run it, which I am sure you already have. Then just rev the engine to about 4K rpm a few times, and if everything is good, you will get oil pressure. This is a somewhat risky method on an older engine, but it will work. Go ahead and flame away at my hacker methods if you want, but results are what count. :firedevil

Like I said, if you really don't want to pull everything apart, and you already ran the engine, I say go for it. I haven't had good results with just cranking the engine until it gets pressure. I also use this method whenever I install a reman 4.0l engine. Since they are assembled somtimes monthes in advance there ie very little oil left in the oil pump to get a good prime.

I guess the proper way to do it would be to tear it apart and fill the entire oil pump gear cavity with vasaline. Once you do that, make sure you fill the oil filter with oil before installing it. Then just start the engine and you should be good.


Bryan C. AKA hack flat-rate mechanic :firedevil

Well here's the update :gonnablow
I trie all the suggestions with no luck.
So I dropped the pan and re-primed the pump this time I put about 10lbs of vaseline in the pump.
Started it up and got oil pressure arty:

But no the engine is tapping!!!!!!!!!!! WTF
Did I destroy it??
Can or will the tap go away?
I'm not real good with engines. Water pumps, thermostat, Oil pumps (I thought) I can replace. But I'm lost when it comes to the valve train etc. :doh:

Nevermind the Distributor wasn't seated properly :wstupid:
Thanks everyone for the help!!!!!!!!!!!!!
I love this club!!!

Go ahead and run it for a while. There are two things that can be causing the tapping. Either you have a lifter that has yet to prime, or your fubar'd the rod bearings. One goes away with time, the other one does not.

Tapping went away. Thanks
I let it run for about 30 min. and went for a drive.
Pressure is good all is well

Just FYI, but I had one lose prime, and took the oil filter off, and filled the center, (the part it actually spins onto) with oil. Let it drain into the engine, and filled it again, several times. Picked up the oil first time the engine cranked.

In worst case scenarios, I have also over filled the engine with oil. Put enough in it that the pump is submerged. Ususally about 10 Qts. and let it sit. The oil will eventually fill the pump, and will have pressure when you start. Just don't run it for very long at all. Drain the excess oil, and you are good to go.

After cooking the mains on a 360 I rebuilt, I´ve packed the oil pump with everything from bearing grease through 90 wt. gear oil, blue moly gear additive and STP (they all worked) to Vaseline. Vaseline seemed like a good idea (thicker than oil, thinner than grease), I´ve used it as a coating on other parts and it`s worked out well (greased the inside of a corroded starter solenoid with vaseline, ten years later it still looked good). I usually fill the oil filter about half full, really makes a mess, full makes even a bigger mess. I´d thought about pouring oil into the filter feed, seems like a good idea, I´ll try next time.