I put an engine together with an 89 block, 94 head, 00 intake, 95 exhaust. Fired it up and it has no oil pressure? The cylinders looked great upon install, still had the honing marks.
It has a bit of pressure when throttled but no more than 5-10psi. It sounds fine when running but at 1500-2500 rpm it sounds terrible, under and above those Rpms sounds fine. The lower end was from a jy engine with <150k on it. I'm guessing the oil pump is toasted or lost its prime while sitting in the jy for however many months? Need advice before I break the engine down again, thanks in advance

 

Once I have the same problem, no oil pressure upon start. I friend that was by told me to remove the oil pressure sensor, and pour oil through that hole in order for the oil to reach from up down to the pump, the to try to plug the hole with my finger, and crank the engine for a couple of cycles, I did it, and then install back the pressure sensor, sure thing it started working correctly, and oil pressure when up to normal.

That may or may not work for you, a couple of more turns will not harm, but if does not work I recommend you to check that oil pump before starting the engine again.

 

Thank you, I'll try that tomorrow morning when I have the day off! Hopefully that's not it, I'd love for the engines issue to be just the pump haha.

 

Before you get to concerned. What brand of oil filter do you have on it now? Also you can barrow a mechanical pressure gauge and connect it where the oil pressure switch goes and verify the pressure.

 

I'm running the same k&n I have Been for the last year or so ( switched a few times now of course ) it's brand new, I believe it's the ps-2004

 

Remove the filter and cut it apart and inspect the filter. See what it looks like.

Oil pumps move volume. They DO NOT create pressure. Pressured is created by a restrictor on the outlet of the pump. (think of a garden hose flowing water freely. Now put your finger over the hose. You've just created pressure. Same concept with the oil pump.)

The clearances between all the metal parts (bearings, main bearings, etc) also create pressure. Huge worn out clearances leads to low oil pressure.

 

Pressure is created by the combination flow volume and flow restriction so if the pump is not flowing as much as it should then it can be the reason for low oil pressure. The garden hose example only works if there is forward pressure so that your finger can create a back pressure when it closes off the hose. Attach the inlet of that hose to a bucket of water and you will get flow, but when you put your finger on the other end you will only build up as much pressure as gravity and the depth of the water column will produce.

So the pump can be the cause of the loss of pressure if it is not pumping as much volume as it should due to worn pump gears, or if the over pressure valve is stuck open(not sure if the Jeep pump has this but I know the old Ford pumps have built in pressure relief valves which we used to shim to make more pressure).

 

i agree with above, check pressure with mechanical gauge, our engines oil sending unit gauges are infamous.

 

Of course the pump makes the pressure. Those of you who doubt that, try it without the pump. . The less of it that leaks out, the higher it will be. (leaks say, at cam bearings, rods...lifters)

An 00 intake on a 94 head? Ok...(that bugs me). So you didn't change the lower end, (crank) in a different block. Just if you read that right it might read you changed something. Did you have the pan off? Oil pump pick up screen is not clogged? I'd think if it runs at 10 Lbs, it's at least primed.

You have oil up in your rockers? I'm just tossing around some stuff..checking it with a known good gauge makes sense. Also the hole for the sender can even plug up. Me, I might remove the sender and fire it for a second and see what happens.

I've never removed my Dizy and put a big flat blade in a drill and ran the pump until I saw oil at the rockers. I've just cranked with the key to prime a new install.

I'm somewhat at a loss. Sounds "terrible", clacking, or knocking? Maybe check the pressure with a mechanical, like said...

 

By terrible I mean it sounds like rods slapping ( loud tapping) I started it today and it has pressure again, 20-30psi... Same sounds
Pulled the valve cover and fired it, 4/6 rocker sets are spraying (enough to tag the hood) and the others are non cooperative, I suppose that'd make rocker/rod tapping? Is this still a pump issue, or a cam/lifter?

 

I had it all disassembled, everything looked mechanically great, had them inspected by a coworker that's been working engines for 25+ yrs.

 

The 00 manifold is an upgrade for 20 something horsepower, bigger ports, better flow.

 

Lifters not pumping up and other valve stuff can make a pretty hearty knock.
I'm thinking if you have pressure and it's not getting up to the rockers, you might have lifter issues.

Come-on somebody...why do I feel so lonely! I thought Cruiser found something better than MMO to help with lifters...You might check the push-rods them selves, make sure the passage is clear. Just thinking not having oil up there is a sign something is wrong in that direction. Never done it that I remember, but I've wondered if a guy could dribble some solvent down a push-rod so it soaks a lifter, leave it a while. The rocker pivitos (and the rest), might ware pretty fast is they are dry, might want to watch that.

I'm not at all clear on the oil galleys. I'd think if 4&6 had pressure, the others should as well. I guess if it was me I'd check those push-rod tubes, for lack of a better idea at the moment.

 

Maybe use diesel fuel, or WD40, down the pushrod, then work the piston in the lifter by pushing it down repeatedly with the pushrod to break lose any sludge that might be in it. Afterward remove the pushrod, pour oil down on the lifter then work it again with the pushrod to get some oil back in it.

If there is something blocking the oil from getting to the lifter though, that would require a tear down and hot tanking most likely.

 

X2, good idea. Work the plunger in the lifter...feel it compared to those that are working. Maybe even "rap" on it somehow?