Dave51

Although since the next step is going to get pretty involved IIWM I'd do another oil + filter change before I took the plunge. I mean, 110,000 miles? I'm the first guy to advocate pulling the pan, checking pump and bearings but I'm just not seeing bearing or oil pump wear given the sudden onset.

betic72

I've got 10w30 in there at the moment. It's the "suddenly" part of this that is odd to me as well and has me perplexed.

Dave51

Just got back from an errand, I'm 20 PSI at hot idle and 140,000 miles. 40-45 PSI with any kind of movement.

Ralph77

Do you know what page you saw that on? Wondering if there are other specs for compression and what not there too.

Dave51

page 9-118.

Compression on page 9-116 (120-150).

Ralph77

Thanks for that. I could never seem to find these in the FSM.

betic72

Well, I changed the oil and put on a Mopar filter. Oil is 10w30. Ran the engine for 6 minutes at idle after heating to 210 with the pressure hovering around 18psi, occasionally dropping to 15psi. I revved the engine to 1250 rpms a few times after this and let off the gas to see if it had any effect. Let it idle until it hit 10 minutes with no ill effects. So, I guess it was a faulty pressure relief valve? Looks like it. It's still low, but within spec so I'll call it ok for now. Thanks for helping troubleshoot. I'm still questioning if this engine actually has 110,000 miles on it. If so, it's been a hard 110,000. The engine runs louder than the other 5 XJ's I've owned. I linked to a video of it running so you could hear it. Sounds like a fleet of typewriters going to town. After I move, I'm hooking it up to a compression tester and see what I find out there. Anyway, guess we'll mark this as solved. I'll update if it takes a dive on me when I decide to get it out on the road.

Dave51

There are 2 pressure relief valves, one in the filter



and one in the oil pump. If the one in the oil pump sticks open then you can lose oil pressure, but given these results it could be simply that the filter was due.

Yeah, that's up there.

Amen to that, brother.

third coast

I wonder if the oil pump relief valve is sticking and it will clean up with an oil change or two. I think I would do short interval changes for the next couple. It is possible that poor quality oil and infrequent changes are to blame for the low oil pressure and valve train noise. Maybe a few lifters will clean up also. Let us know.

betic72

Just an update. I took the Jeep out for it's first drive since letting it run in the driveway. After I went about 4-5 miles, the pressure dropped again and stayed around 10psi when at idle. When on the gas, it was around 20psi. So, it's back in the driveway and I'm going to give it a go with changing the pump next. As soon as my wife gets back in the other Jeep I'll head to the parts store, pick one up along with a rear main seal since I'll have the pan dropped and I already have oil pan gasket so that should be about it. Will probably be a couple of hours before I can run to the parts store, so if anyone has some thoughts before then, I'll be checking in. Otherwise, I'll update with progress when I get the pump on.

dave1123

I'm pretty sure the low idle oil pressure problem on these XJ's is due to the restriction of that banjo bolt that mounts the adapter. I think the problem would be cured if you could screw a filter directly on to the block. Lacking the room for that, maybe a remote filter would work. Autozone sells a remote filter adapter that replaces the stock angle adapter and has 2 hoses that lets you mount a filter on a fender or anywhere else the hoses reach. Is it worth $50 to find out? The beauty of this adapter is you could use that BIG Ford filter in an upright position and not get any drainback. The only thing I would do is replace those wimpy barb fittings in the kit with hydraulic hoses.

Dave51

Beautiful day in New England, was out on the lake fishing so here a little late.

Get some PlastiGage and check the clearances of a few rods and mains (definitely the front and a couple others). Maybe because I have a subwoofer hooked up to my computer, but IMO not all that noise was lifters.

Give some thought to the oil pump. If the bearings are a little loose, but not bad, consider going to a high volume pump. You'll probably have to bang out the pan a little bit, but NBD.

Check the "bad" oil pump. Clearances are in the FSM.

betic72

Well, final update on the Jeep. It took me a bit longer because our house was being inspected before sale and I couldn't be here working on it during that time and weather also interrupted. Once I took off the pan and the first long bolt of the oil pump, while holding the pump and literally touching the other bolt, the pump fell off into my hand. It was broken/cracked apparently across the wing with the shorter bolt in it. Either the last person who changed this beat it to death while installing the pickup/screen or overtorqued it, I don't know but this was clearly the problem. When the engine heated up, the pump would drop slightly because of the 1 bolt and crack and suddenly there's a loss of pressure. Also, the oil would then be hot, have a lower viscosity and flow more quickly out of the crack. I went ahead and changed the rear main seal while in there, but because of weather and the loss of time with our house sale, I wasn't able to clean up and access the bearings to get an accurate measurement of clearance. I'll leave that one for a day when I've moved and have a garage.

So, I took the Jeep out for a spin after letting it run in the driveway for 10+ minutes and the pressure is now fine. It starts off around 45psi cold and drops down to a little over 30psi when the coolant temp is at 210 degrees and driving for a bit. With gas, it goes back up to 40psi at that temperature. So, I'm marking this one as solved. A cracked in half oil pump probably isn't a normal thing, so this wouldn't be a solution for everyone, but I'm glad it was for me. Also, the Jeep is significantly quieter now. The lower end rattling I could hear isn't from the motor (stuck a mechanics stethoscope on it). It appears to be coming from the exhaust. Maybe a bad cat or something. Still investigating that.

Finally, I do have one last question. I had placed a jack between my axle and frame to lower the axle about another 1/2" or so and when I lowered the jack on the passenger side, a piece fell to the ground below the wheel well. I can't for the life of me figure out where this goes or what it is. At first glance, I thought it was part of the bump stop. I've looked at the Jeep and through the parts catalog and can't find this thing. So, if anyone recognizes what this is and where this goes, would love to get it back in place before trying to drive it for a long time. But, it's been 10 miles so far with no problems. Anyway, thanks for all the input and helping me walk through this. I'll post pictures of the broken pump below and that piece I can't identify. The piece is what's in my hand in the 2 pictures.



Oil pump break

Oil pump break with both pieces shown

Piece to ID

Piece to ID

Dave51

I love happy endings!

That part looks like one of those things guys screw into the coils to jack up the vehicle.

Dave51