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MikalCarbine 05-21-2013 10:04 PM

Zero Oil Pressure - Manual Gauge Verified
Long story short, I did a few water/mud crossings, got stuck in semi deep mud twice, probably enough to sink the oil pan. Afterwards my oil pressure was crazy up/down and I had some engine noise at 2500rpm so I did the following:

-Cleaned oil pressure sending unit
-Changed oil (NAPA Gold and Rotella 10w30) - Came out nasty
-Ran 6oz seafoam in crankcase for 30 min at idle
-Changed oil again to flush (Puralator filter and cheapo 10w-30)

This didn't change much so I hooked up a mechanical gauge, at cold start I was getting about 30psi but it slowly dropped to 0-2 PSI at idle once hot and 16-20 PSI at 1600rpm. I even tried clearing out the pressure sending oil valley in the block by running it open with a tube into a pan with no help. At this point I decided to drop the pan and check out the pump/rod bearings and do the RMS while I was at it

The bottom 1/2" or so of the pan was complete sludge, I have a feeling this was blocking the oil catch/screen but the catch showed no signs

I took the pump apart and it didn't show any huge signs of wear. I couldn't seem to actuate the pressure relief valve though, how tough is the spring on this thing? Any advice on how to make sure it is working right and isn't jammed?

I pulled the rear main bearing cap to do the RMS, this is what the bottom portion of the bearing looked like

Doesn't look too kosher but I don't know what I'm looking at with the wear mark in the center, here is the crankshaft at the RMS

I'll be pulling the rest of the bearings tomorrow and taking photos, I'm expecting similar wear especially on the top bearing halves based on the copper/gold specs in my oil/sludge. Any advice with all of this would be greatly appreciated!

MikalCarbine 05-22-2013 07:25 AM

Bump, trying to get a feel of what my options are if the rest of the crank/rod journals are like this. Can I simply replace the bearings to give me some extra time? I can afford a full rebuild and she isn't a DD, probably sees 4,000-5,000 miles a year if that

MikalCarbine 05-24-2013 03:07 PM

So I took the relief pressure valve out of the oil pump, the valve itself showed some signs of wear and the valve bore had some flat scores ("|") in it which the valve might have been catching on...

I pulled the #5 rod bearing and it is slightly scored, along with the crankshaft

#2 was the same way, I haven't bothered with the rest or the main bearings. I'm going to replace the pump and RMS. Does anyone think this scoring is enough to cause me dramatic pressure issues? She isn't my DD so I'm not looking for her to be in 100% pristine condition, I'm just aiming for ~10PSI to wheel it and cruise around. I'll have time for a full rebuild/stroking in a year or two

Offrd 05-24-2013 03:15 PM

The bearings should be shiney like a mirror. Yours look trashed as well as the crank journals. I would recommend a rebuild from your pictures. The cylinder walls are probably also scored. All the oil galleys need to be cleaned, the lifters and push rods also will have silt in them. Sorry.

flflash 05-24-2013 03:25 PM

That picture of the oil pump gear laying on its side when blown up looks like a lot of debris has passed thru it. The real bad news is a oil pump will not pump the mixture of oil and water very efficently and oil/water is not a very good lubricant so you wind up starving bearings for oil and damaging them. The bearings you can't see are the first ones damaged on a 4.0. The oil pumps from the oil pump to the cam bearings first before going to the main then rod bearings. This also makes the cam bearings the first to be starved for oil and the first to see debris when it gets pumped thru the engine.
You really need to examine your cam bearings. I've seen several of these motors that someone replaced the rod and main bearings and still had no oil pressure every time when I pull them down I find damaged cam bearings, everyone over looks them.

MikalCarbine 05-24-2013 05:18 PM

This is nothing a heavier oil can't get me through another 6-12 months with?

KaiserJeep 05-24-2013 06:08 PM

Nope. Rebuild it now or park it until you can rebuild it. If you continue to drive it you will continue to trash internal engine parts, and greatly increase the cost of the rebuild.

As we say around here, it's a Jeep not a submarine. You are the latest of many to discover that you cannot submerge the engine.

Not to make you further depressed, but if you dunked the engine, both axles very probably need a lube change as well. Don't let them sit with water inside them, either.

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