I am trying to prime my freshly rebuit 250 and I cannot get any oil pressure. I know it is pumping oil because I can feel it bog the drill slightly and oil does come out at the gauge tap just no pressure, and the gauge is brand new. I took the valve cover off and oil is getting to the head on some of the rockers but it seems to be a very small amount. I have also rotated the motor several times while spinning the oil pump with know luck. Also I did clean all the oil passages and push rods with solvent and brushes before rebuilding.

You could very well have a bad gauge??? What size drill are you useing? Not that That should really matter. I have pushed Over 25 psi with a 1/2in drill. But I never tried to see just how high it would go.My biggest interest is Just making sure the Block is fully primed before starting it.

Are you turning it the right direction?? It's the same as the rotor, which is 'clockwise'.

If so; you are "sucking air" somehow/somewhere.

Check the various fittings. Next; remove the oil pressure sender & spin the pump till there is a "full squirt" comming out.

Good luck.

If he was spining it the wrong way I really don't think he would get oil anywhere.esp. Up top.

They will pump backward if full of grease/heavy oil first. Once they stop turning they lose the 'prime' & won't (or may not) re start (backward).

Sometimes (reversible) drill motors get switched in the middle of things, by mistake.

You mentioned a "slight" bog on the drill. I have primed different engines using different drills and I usually get a pretty decent bog. You also mentioned that you cleaned out the passages, are you sure the gallery plug behind the cam gear and/or the oil director are both in and secure? Is it a new pump and are you using a gasket with it?

First off thank you for the responses,

Here is what I have tried/found and am still have same problems:
I was using a 3/8 so I tried a 1/2 but that did not help the 3/8 seems to spin with more rpm so I went back to that. I took the gauge off the psi tube and only get drips when spinning the pump. I removed the back side cover and removed the first lifter from its bore and there is flow from the oil galley into the lifter bore but when I put the lifter back into the bore it does not seem to "pump" up as I get no oil flowing out the top of the lifter?? I am using a new pump with a gasket and I JB welded the pick up tube to the pump body. I also checked the pick up tube height/depth before installing the pan so it was not sucking against the pan or starving for oil.

I dont understand the sucking air where could it be sucking air from?? Could the lifters that came in the kit be wrong somehow??

Thanks

F;

It's just not pumping as a 1/4" drill motor will do, or just a 'speed handle'.

From what you say, it tried at some point. Also when you get "the bog" it should stay.

Your going to have to pull the pump & find out. Larry will know more about the 'pick up tube' so give him a call.

Try to make it work on the bench first.

just a simple question. do you have enough oil in the pan. if yes. have you modified the oiling system in any way? such as bypass at oil filter, relief valve in pump, forget to put the front oil galley plug in, if it has a oiler for the cam gear and forgot to put it in. that is a few. what oil are you trying? is it the correct filter? maybe spin the pump faster. tom

Finally got back on the engine and found the cam plug missing put the plug in and it primed right away. A very big thanks to all who posted.!!

Great to hear you found the problem. And is now fine.