No different than letting a car sit for a few days. There is no stress on bearings when just turning the engine over with the starter.

 

I always use plenty of assembly lube.

 

I just did this on mine after a rebuild.. I did it old school filled engine with oil (pan on of course) I had an old dist took it apart and used the shaft that I put into a battery operated drill, with the dist or crank sensor out insert the shaft into the top of the oil pump . I turned drill on and it primed the pump,if you want remove the oil filter and once the pump is primed you will see oil come out of the housing that the filter would normally be attached to,make sure you put a pan under it, oil will come out and pump ,is primed and you did not have to turn the engine.. If you do not have an old dist., you can buy a shaft made for this that will fit into the oil pump not expensive, or take an old large screwdriver remove the handle and put that in the drill it will work.., Then I would reinstall either dist or crank sensor disable start mode (pull relay) and crank engine a few times to circulate oil.. That`s it really pretty easy..

 

If the engine sits for a few days, the filter is still full and the galleys don't drainback through the pump.

If you remove the pump, the galleys usually drain back and empty themselves - dry start.

And, if the oil pump isn't primed, it may not pick up oil - going from dry start to dry run, and into bearing failure.

Do it once. Do it right. It's not worth the risk.

As I mentioned earlier, a Small Block Chevvy oil pump priming rod will fit the AMC I6 oil pump, once you remove the collar from the tang end.

You can also grind one yourself out of a 1/2" round rod, measure the drive tang on the bottom of the dizzy shaft and shape your 1/2" round rod end to match.

 

I've done it without priming on many 4.0s by just disconnecting the CPS and cranking. Had oil pressure in a matter of seconds. Less than 10.

Have I been just incredibly lucky?

 

The oil galleys drain into the sump anytime the engine sits awhile. There is nothing to keep it from draining. The anti-drainback valve in the filter does prevent 1/2 of its oil from draining, the other 1/2 drains out the center outlet of the filter into the main galley then gravity takes over and it goes into the pan. But whenever you do a oil & filter change you are starting up with a drained system!
UNLESS it is a newly rebuilt engine (must use assembly lube) there will always be residual oil on the bearing surfaces

 

Hm.

Since the engine oil pump is a positive displacement gerotor type, that alone can serve to at least VERY MUCH slow down the drainback of oil, if it doesn't stop it totally.

Unless you're engine's been sitting for a couple of months or so, you shouldn't get a "dry start" from it. This is why a stored vehicle in running order needs to be kicked over for about 5-10 minutes every couple of weeks, just to keep the gaskets wet and circulate the oil (run until the engine hits op temp, give it a couple of minutes or so, then you can shut down.)

Considering I've let engines sit for up to two weeks and gotten oil pressure immediately on starting with a mechanical gage, I think it safe to say that the drainback is minimal (if the galleys had drained out, pressure would not have built up for 5-10 seconds as they filled back up, since there is no resistance to flow - therefore no pressure - until that happens..)

 

So after reading your guys posts I've tried taking off the coil wire and the crank shft sensor thing and turning it over ... It didn't build any pressure. So after reading that if you prime it by taking off the distro take off the oil filter as well so you can see the oil come up.. My question now is could I just get a funnel and pour oil down the filter tube into the pump to prime it?

 

If you're not building pressure then something must be wrong.

Bring the engine to compression stroke on #1 cylinder. Take the cap off the distributor and verify the rotor is pointing just past the #1 spark plug wire and mark the outside of the distributor body. Remove the distributor. Prime the oil pump with an electric drill. I fashioned a tool using a very long bolt and ground down the head of the bolt to fit into the slot of the oil pump shaft. Some people cut the handle off a large flat blade screwdriver, but I hate wasting a tool like that. Run the drill until you feel it get very tight. Reinstall the distributor- this will take a little patients. you need to line of the slot in the oil pump drive and you will need to turn the rotor shaft counter clockwise a little. When the distributor is installed the shaft will turn clockwise a little and you will want it to end up at the mark you made previously. put the cap back on and start the engine. Check oil pressure. If you felt it get tight when you primed the pump with an electric drill but your gauge still doesn't read pressure then I would say there is something wrong with your gauge.

 

Worth a try. I've never had one not build pressure in seconds from cranking with teh starter. .

 

Older thread, but I'm doing this now. The Haynes manual says nothing about priming the pump. Went straight to the factory manual. Attached the page info. Dont think i will put vasoline in it.

 

I've built countless engines and replaced a few oil pumps on running engines. I've never put anything in the crankcase / oil pump - except oil. kill the fuel pump or ign one, crank it over until there's pressure, and be on your way. if it cranks over 10 seconds without pressure there is another issue.

 

Priming a pump after a oil pump change is hogwash. I can see it on a new rebuild but if the engine has not been rebuilt to fill the gallies. The residual oil left on the surfaces is more than adequate until pressure builds......You don't prime the pump after car has been sitting do you. And yes the oil drains out of pump b/c there is nothing to hold it in....gravity will empty it

 

Well, it ran for 30 mins and didnt blow up so I guess its ok. I was especially concerned because some kid that had this Comanche put a premium instrument panel in it, but the only thing that works is the speedometer. But, there appear to be no leaks from the rear main, oil pan or the valve cover gasket. I read some of the rear main posts, I didn't clean this one up beforehand but I suspect the primary leak was the valve cover gasket leaking back to the rear of the engine and appearing to be a rear main. The oil pan gasket seemed to be somewhat disintegrated, so it may very well have been leaking there also, but it would probably be very good advice to clean things up and have a good look around before declaring it a rear main leak. The oil pan deal was a fairly nasty job, but I'm glad I took it off, there was 3/4" of sludge in the bottom of the pan and the screen was partially clogged on the pump. I also wanted to strip the pan. And as easy as it was to replace the pump, it would be pretty foolish not to replace it unless you had done so very recently. Also, they were pretty expensive but I really like those FelPro gaskets, they are fantastic, very little RTV needed

 

Jeep 4.0 Oil Pump Priming

Don't mean to revive an old thread. Just finished a 99 Jeep 4.0 Engine Rebuild, forgot to pack oil pump with vaseline. Was getting zero oil pressure during cranking and during 1st 30 Seconds. Removed Dist. Ran with drill no dice. After all the rebuilding and installing definitely not in the mood to be pulling oil pan and pulling the pump to pack it or to prime in a bucket of oil.

So if you forget to pack your pump or have issues priming it all you need is.

1.) 1 Piece of Cardboard
2.) 3 Inches 5/8 Heater Hose.
3.) One Spark Plug4.) One Zip Tie5.) 1 Shop Vac (preference of a short hose)

Cut the Cardboard to just a little under the size of your shop vac hose, cut the heater hose, put the spark plug or any plug of your choice, zip tie it, cut the excess. Put the Hose that you just made with the plug on it onto the threaded portion of the oil filter adapter (return line) put the cardboard over the heater hose against the filter housing, put your shop vac hose onto the piece of cardboard and hold it tight. Turn on the shop vac for a min or 2 vac until oil shows on cardboard. Remove all said items. Now, all done! Spin oil pump drive with drill to verify pump is primed.

Easy, now go spend that extra 4 hours I just saved you with your family!