304 V8 - Can't get ANY oil pressure

2478 Views 20 Replies 9 Participants Last post by 254Triple, Mar 5, 2021

254Triple

Discussion Starter · Feb 28, 2021

1972 Jeep CJ5 with a 304 V8. All fresh rebuilt, new front cover, new oil pump basically everything new. I set the engine in frame today, put the break in oil in via the distributor. I am using the old distributor modified so I can attach to my drill to prime the engine. I also have a mechanical oil pressure gauge hooked up to the sending unit port. I started running the drill "clockwise" to build pressure and nothing, gauge never moves. I reversed the drill for a dozen or so rotations and then forward again and still no oil pressure.

I removed the oil filter(it was dry) and the oil pump cover plate. I packed it with moly engine assembly lube, put the cover plate back on. Re-Test - Still nothing. Pulled the oil pressure relief cap off, spring and took out the plunger. Did not see any blockage/problem and plunger moves easily into recess hole. Installed spring and cap, still nothing on Re-Test.
I remember when I set the new oil pan on, I verified the sump pickup was within specs, put blu-loctite on the threads before screwing into block. I have 6 qts of the break in oil in the pan right now. According to my dipstick it is about a qt overfull, but filter is still dry so it will drop and I will adjust as needed once I get oil pressure.

Anybody have some ideas/insight as to what I can try next? Everything I have tried still no oil pressure.

1 - 20 of 21 Posts

jeepdaddy2000

· #2 · Feb 28, 2021

You may need to run the drill for up to thirty seconds.
Insure your drill is sufficiently fast in order to pick up the oil.

If the above criteria are met and you've packed the gears, then the issue is between the pump and the pick up.

Plugged screen
Loose pickup (sucking air)
Passage blockage
.

JEEPFELLER

· #3 · Feb 28, 2021

I worked in a performance machine shop for about a year before I went in the Army---Mostly a tear down an cleaning guy.

A feller came in cussing out the boss.

He had fried his new engine.

Boss man never got upset, the boss explained if it was something he had machined wrong, he would take full responsibility.

The engine was machined at the shop------the owner built it himself

He continued blaming the boss.

We unloaded it off of the guy's truck and put it on an engine stand and removed the pan.

It really had the burned smell.

The boss told the irate customer that it was not the shops fault at all.

"How do you know &^*($# that????"

"Well sir, the tell tell problem is, this is the wrong pickup tube and is perpendicular to the oil pan, it's impossible for it to submerge in the oil"

(It was up in there around the crankshaft caps---sideways!)

Customer just could not accept it!

He finally got a free ride in a police car!

----JEEPFELLER

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JVino

· #4 · Feb 28, 2021

I just did mine about a month ago. Took about a minute total with my hammer drill. After I was done, the motor on the hammer drill was smoking. Keep going. During this time, lifter to piston number 2 was flowing at all. I was panicked. My neighbor told me to rotate the crank, via balancer bolt, about a half turn. I did that and bingo. Oil was flowing nicely. If giving it more time under the drill doesn't work, refer to JeepDaddy. Good luck.

jeepdaddy2000

· #5 · Feb 28, 2021

Addendum:
You will know when the pump picks up the oil.

It will try to twist out of your hand.

Be ready:surprise:

Reactions: 1

254Triple

Discussion Starter · #6 · Mar 3, 2021 (Edited)

FIXED IT !! I went out this morning and again used the drill in the distributor to spin the oil pump. After about 90 secornds, nothing, filter still dry. So I took out the oil filter bypass disc and spring. The disc looks homemade, not round but more octagon shaped. Tried spinning the drill again, nothing.

I undid the fitting to the mechanical oil pressure gauge just above the oil filter and put my vacuum suction/brake bleeder on the fitting and withiin 20 seconds it was pulling oil out of this. I put the line back on and back to the drill. Started the drill and within 5 seconds I had 35PSI oil pressure. Ran drill for about a minute, rotated crank, ran drill again and all pushrods are pushing oil out down the rockers. Previously packing the pump and letting drill run forever did not get me any oil pressure. Maybe the way I did it will help somebody out. Appreciate all the responses, now on to the next task.

Reactions: 2

254Triple

Discussion Starter · #7 · Mar 3, 2021

Held 35 psi pressure the whole time I had my drill on it. Stopped and came back about 15 minutes later and again cannot develop any oil pressure. So I put the oil filter bypass disc and spring back in, took the oil pump back off and packet it with vaseline. Put it all back together and still nothing even trying the vacuum portion again, this time nothing. I cannot think of anything I am missing but something is just not right.

Matt1981CJ7

· #8 · Mar 4, 2021

Damn, that's frustrating.

Since altering the oil filter was the only thing that allowed you to build pressure, have you tried a different filter?

Matt

Shawn Watson

· #9 · Mar 4, 2021

Yeah, wow. It's got to be a "vacuum leak" in the pump (gaskets, midplate, terrible gear/case clearance), doesn't it?

Shawn

jeepdaddy2000

· #10 · Mar 4, 2021 (Edited)

So, initially the pump wouldn't pick up the oil. You ran the pump and no oil in the pump or galleys. Used a vacuum pump on a galley and the oil pulled into the pump and everything worked as it should. Shut it down and later the pump wouldn't pull oil again.

Sounds like an issue on the vacuum side of the pump as the pump won't pick up the oil. If there were a blockage on the pressure side, the drill would either stop or drag badly under the oil in the pump trying to push through. If it were the bypass, the drill would have drugged down and there would have been oil in the pump during the initial tries to prime as the oil would still be flowing through the pump.

There has to be an issue between the pump and the pick up. A bad/ripped gasket, cracked/plugged up pick up, oil too thick, etc.

I would start by double checking the pressure release valve simply to insure there isn't another issue. Then I would drop the pan, remove the pickup and check to see if there is suction there when the pump is spinning.
If so, then the pickup must be the issue. Check for cracks and blockages.

You might want to check any galley plugs on the vacuum side to insure it is sealed. If memory serves, there is one on the face of the engine.

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JEEPFELLER

· #11 · Mar 4, 2021

Where the pick up tube is driven into the oil pump.

Is there any sign that maybe the tube may have buckled inward creating a dimple or void between the 2 pieces (which might suck air).

-----JEEPFELLER

254Triple

Discussion Starter · #12 · Mar 5, 2021

2

So today, I went at it again. Loosened the oil filter and tried it just to see if an air lock would clear(hey, I'm desperate

. Nothing. I took the Oil Filter Bypass back out because the spring looks ok, but the little disc itself looks like someone made it with tin snips as it is kind of octagon shaped and not even at all. Tried again, Nothing

Took the oil pressure relief valve spring out, and put cap back on and tried it. Still nothing. The litlle needle portion that the spring pushes on is stuck tight in the bore. Not sure why as I had it moving in and out the other day with very very slight drag, but now it is in there tight. Ok, so I go get the original front cover with the oil pump cover. Take off the oil pump cover and compare this original "factory" as far as I know to the new one that came with new front cover. They are different. The pic of the one below is the NEW pump cover. Notice it only has the 1 hole for the Oil Filter Bypass valve. The original/old one has two holes right across from each other and the spring and disc fit much easier in this larger hole.

So, I wanted to try this old cover but upon trying to slide the needle in with the pressure relief valve, it was very tight. I am sure it is due to sludge buildup in the tube. So I left the Oil Pressure relief spring and needle out and put cap back on.
Mounted the adapter, put the filter on, put the oil filter bypass spring and disc back in and tried it again, NOTHING.

My brain is spinning and I can't figure out if by leaving the entire Oil Pressure relief spring and needle out would cause a no oil pressure situation. If so, I can clean the bore up and put it in and try again tomorrow. Can someone let me know if they believe leaving that out would cause a no pressure scenario. Sorry for long post, just trying to get it out right so you don't get more confused than me. Thanks for all the feedback to everyone.

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254Triple

Discussion Starter · #13 · Mar 5, 2021

One other thing I am going to try if next test fails is drain the oil out, and put my endoscopy camera in the drain hole and go up and see the pickup tube, hopefully see the line where it might be wet from oil level and then while my camera is in there, I will shoot air pressure in through the sending unit and see if I get any bubbles etc that would be a leak?

shadoow

· #14 · Mar 5, 2021

I've got a 258 6 cyl., but the relief/bypass setup looks to be pretty much the same. Years ago I had a problem with a relief valve part & long story short I ended up removing the relief valve pieces and blocked off the hole where the relief valve & spring went. I got the blocking piece from Bultear (sp?). A lot (maybe most) oil filters today have bypass capability so no need to have the relief in the oil filter housing.
Here's a link to the thread on mine:
https://www.jeepforum.com/forum/f8/258-oil-pressure-relief-bypass-2416913/

Reactions: 1

cjoffroad

· #15 · Mar 5, 2021

254Triple said:
So today, I went at it again. Loosened the oil filter and tried it just to see if an air lock would clear(hey, I'm desperate . Nothing. I took the Oil Filter Bypass back out because the spring looks ok, but the little disc itself looks like someone made it with tin snips as it is kind of octagon shaped and not even at all. Tried again, Nothing

Took the oil pressure relief valve spring out, and put cap back on and tried it. Still nothing. The litlle needle portion that the spring pushes on is stuck tight in the bore. Not sure why as I had it moving in and out the other day with very very slight drag, but now it is in there tight. Ok, so I go get the original front cover with the oil pump cover. Take off the oil pump cover and compare this original "factory" as far as I know to the new one that came with new front cover. They are different. The pic of the one below is the NEW pump cover. Notice it only has the 1 hole for the Oil Filter Bypass valve. The original/old one has two holes right across from each other and the spring and disc fit much easier in this larger hole.

So, I wanted to try this old cover but upon trying to slide the needle in with the pressure relief valve, it was very tight. I am sure it is due to sludge buildup in the tube. So I left the Oil Pressure relief spring and needle out and put cap back on.
Mounted the adapter, put the filter on, put the oil filter bypass spring and disc back in and tried it again, NOTHING.

My brain is spinning and I can't figure out if by leaving the entire Oil Pressure relief spring and needle out would cause a no oil pressure situation. If so, I can clean the bore up and put it in and try again tomorrow. Can someone let me know if they believe leaving that out would cause a no pressure scenario. Sorry for long post, just trying to get it out right so you don't get more confused than me. Thanks for all the feedback to everyone.

The oil pump cover you have pictured above does away with the oil filter bypass. If you're trying to put the little spring and disc in the one hole then that's probably your problem. If you intend to run that oil pump cover you'll need an oil filter that has the bypass built in.

Where did you source your new timing cover/oil filter cover? Did it come with a new oil filter adapter?

Hurricane4

· #16 · Mar 5, 2021

This is the oil filter I use on my '79 CJ5 304:

http://www.summitracing.com/parts/wix-51258/make/jeep/model/cj5/year/1979

254Triple

Discussion Starter · #17 · Mar 5, 2021

Purchased front cover and pump cover thru Summit a a complete kit, but it is a Crown part. Current filter is a NAPA gold 1258, I just went and picked up a WIX 51258 which is same filter. That is good info to know on the bypass, I will just leave it out. Going to try and get the plunger out of the new pump cover and see why it decided to bind up. I have 2 other new plungers. With the spring pressure from the spring that goes in there, I can't imagine there is enough pressure to begin to move that plunger, but I will put it back in with a free moving plunger.

Matt1981CJ7

· #18 · Mar 5, 2021

A 12-gauge shotgun wire brush works nicely to clean the bore of the plunger, FYI.

Also, you might want to check the clearances between the pump gears and the housing and the cover plate.

Matt

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254Triple

Discussion Starter · #19 · Mar 5, 2021

So far I have taken the old pump cover off and I hooked vacuum source up to the port on the front cover where the oil pump would suck oil from sump. No oil came through after about 5 minutes of holding vacuum on the port. Attached pic shows where I hooded vacuum and I also noticed the gasket that came with the front cover kit was blocking another port/channel. Not sure where this one goes, but the oil pump adapter does have a hole/port in it that would match up to this one on the front cover. Not sure what that little port is for but it would have been blocked off by the gasket. Don't mind the vaseline and gasket material still on there, I will get all that off. I checked a new gasket that I have with a brand new Melling oil pump repair kit and it does have the hole in it so it would not block this off. Maybe that port is to allow air/oil flow through to start suction?

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cjoffroad

· #20 · Mar 5, 2021

254Triple said:
So far I have taken the old pump cover off and I hooked vacuum source up to the port on the front cover where the oil pump would suck oil from sump. No oil came through after about 5 minutes of holding vacuum on the port. Attached pic shows where I hooded vacuum and I also noticed the gasket that came with the front cover kit was blocking another port/channel. Not sure where this one goes, but the oil pump adapter does have a hole/port in it that would match up to this one on the front cover. Not sure what that little port is for but it would have been blocked off by the gasket. Don't mind the vaseline and gasket material still on there, I will get all that off. I checked a new gasket that I have with a brand new Melling oil pump repair kit and it does have the hole in it so it would not block this off. Maybe that port is to allow air/oil flow through to start suction?

The port you have circled in orange is the oil pump/filter discharge to the block.

The area you have circled in red is where the oil pump relief valve would relieve pressure back to the suction side of the pump gears.

The actual sump suction is below the areas you have circled inside the pump casing just above the word gasket in your picture with the discharge to the oil filter directly across from it.

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