304 Seized Oil Pump

I’m working on my 74 cj5 with a stock 304. Earlier this month while driving up my hill the jeep died. A quick check showed no spark so I replaced the electronic ignition. No spark still, I found the rotor not turning, distributor drive gear was stripped. After trying to track down another stock distributor for a few weeks I finally just ordered a msd distributor drive gear. I installed it, put it all back together, still no spark. The new gear is stripped. So I try the oil pump with a screw driver and it’s stuck.

I’ve heard of a lot of things but an oil pump seizing in a running motor isn’t one. Anyone have thoughts? Maybe a good source of a quality oil pump?

 

Not in a jeep but a 302 ford motor, A small piece of paper/foil gasket about 1/4 x 1/4 inch found it's way to the oil pump and locked down the close tolerance between the gear and case Not between the gears.

 

I would add as well what if any damage was done by its locking up,

 

An uncommon but known problem. Usually pieces of old umbrella seals or a chunk of a nylon cam gear. The mess will block pickup screen and then when the bypass valve opens, a chunk gets sucked up into the gears, usually sheering the distributor gear roll pin.

 

Could be a foreign body.

Mmm. I would expect to take the timing cover off and look, at the very least. Sometimes replacement timing sets are machined wrong and the oiling from the cam end is blocked. Oil is supposed to come out from the end of the cam and through passages (grooves) in the back of the sprocket. Usually this defect destroys the distributor gear, but I suppose it could starve the top end of the oil pump shaft of oil, and make it seize in the timing cover.

SOme pictures here - Timing cover & chain sets ?? - International Full Size Jeep Association There are more threads about this issue on IFSJA and the AMC forums.

 

I believe foreign body is correct. I checked again last night and am getting a little bit of movement in either direction making me suspect theres something in the oil pump drive gears. I’m working on another project for the next few days, then I’ll pull the timing cover.

On that note I’m seriously hoping that timing cover is fine. Some time on bulltears sute the last few days suggest this 304 could get very expensive very quickly. Thank you very much for the link Tim.

 

You said that distributor gear was stripped....i would say you could have metal saving getting in the pump and locking everything...

 

Found the culprit. I’m still unsure which occurred first. But the oil remote filter housing was full of trash. Some looked like coked oil, and of course distributor gear debris. The worse news is the timing cover is hashed. The main oil gear pocket is badly marred as is the remote plate the gears ride against.
So for the sake of getting her moving for however long it lasts I went ahead and installed another gear and melling oil pump kit. This motors Been living on borrowed time for awhile anyway. Number one cylinder was rust seized when I got the jeep a year and a half ago. She’s a runner for now though and oil pressure looks to be about the same if not a a bit better than before. In the mean time I’ll start getting more serious about figuring out what to do long term for a motor.

 

If you haven't already, you might think about dropping the oil pan and checking for debris in it and the pick up tube. While you are there, might also drop a main and rod cap and take a look at the bearings, which would help give an idea of the health of the bottom end.

 

That is exactly the kind of adventures which is unpleasant, needs a lot of time to check all... add days for checking and cleaning. If there is metal, maybe a magnet will help.
I hate when it is broken glass (in the kitchen, or any place). Take time, get new parts, and a "new" Jeep will surge in next future.

 

I had the rear main cap of doing the rear main a few months ago. It wasn’t great. Her days are numbered. But then I suppose I said the same thing about 12 years ago with the 75’s 258 when I pulled that rear main cap for a rear main seal. I’ll pull the pan again. Not right now though. I need this out of my main working bay.