I know there is a thread already discussing oil pressure problems but my symptoms are a bit different. So I bought my 01 xj about 6 months ago and ever since I was noticing I was losing coolant, truck turned off while idling randomly, my oil pressure was low and my oil started showing grains of sludge at the end of my dipstick right after I changed my oil. Turned out my head was cracked so I replaced it a few days ago and it is working better than ever with plenty more power than before but... I noticed my oil pressure is still running at about 20 psi even while driving around and it is still turning off randomly while idling. Not sure what normal operating pressure is but when I first bought my xj my pressure was constantly around 40 and now around 20. So my question is do you think my oil pump or oil screen could be failing or clogged and that could be the cause of my low oil pressure and my vehicle turning off? Thanks everyone!

 

Does it turn off smoothly as if u turned the key off or does it make any noises or shudder and shake?

 

everything runs smooth and turns off smooth. Even before I swapped out the head it ran and turned off smooth which is weird. It turns off about once a day for some reason. The rpms will drop and it will just shut off.

 

Once damaged to a certain point, engine bearings will continue to wear until failure, i.e. rod kisses the block.

 

Damn.. I didn't even think of that. Do you think my rod bearings are shot? It runs fine. Is there any way to postpone the death of my bearings lol? I know routine maintenance but maybe a good additive or change up in oil weights? Really not trying to spend a fortune on rebuilding my engine after I just replaced my head.

 

If it runs fine and shuts off without sputtering or warning, see if you can pull any codes. Mine would do that and it turned out to be a general pcm problem. I unplugged it, reset it and it has worked fine ever since.

 

Remove the oil pressure sender and let the little port flush itself out. If you have crud on the end of the dipstick, you might also have crud partially blocking the passage for the pressure sender. It's pretty small. Screw a mech pressure gauge in there while you're at it to see what the pressure really is.
The random shutdown problem is most likely unrelated. Does it start right back up?

 

First things first..DO NOT USE THICKER OIL or ADDITIVES. Now you said your oil was gunky looking. Antifreeze will make oil gunky and create sludge so I would focus on that first. If your pressure is 20 at idle your bearings are probably ok. Since it stays at 20 when driving it sounds like it is starving for oil from a clogged pickup screen. I would drop the pan and inspect for sludge. While you have the pan off this would be a good time to inspect the bearings too.

I repeat, DO NOT USE THICKER OIL or ADDITIVES. A healthy machine is a well oiled machine, not one that has restricted oil flow.

 

^^This is where I would start!^^

 

Do you just remove the oil pressure sender and then turn the XJ on for a few seconds? How much oil is going to come out in this process?

 

A lot. Be prepared. A couple of seconds.

 

Run a hose from the sending unit to a bucket....

 

step 1- verify oil pressure on engine at 210 degrees at idle and then at 1600 rpms record spec. if above 13 psi at hot idle and 37 plus at 1600 or greater oil pressure is in spec. if not proceed to step 2.

step 2-remove sending unit and run a hose from the hole for sending unit into a clean bucket, and run engine for a few seconds. see if any crud comes out if so pull oil pan
and inspect the pick up tube screen.

step 3- if you do indeed have low oil pressure how long has it been since the oil was changed? what weight oil? what brand of filter? if its orange get a different filter, preferably wix or mopar.

step 4- if all criteria in step 3 is good, inspect rod and main bearings for excessive wear. IE excessive amounts of copper showing on the bearing (more than 25 percent) or several minor grooves on the bearings. if grooving or excessive copper is exposed inspect the main and rod journals on the crankshaft for excessive wear. do not let the bearing caps get mixed up they must go back on the main journal or rod cap whci they were removed from... and in the same orientation.

also does the jeep immediately restart? have you checked you're battery cables??? make sure they are all tight. all ecm terminals tight? check all the engine sensor connections and make sure they are secure. if the above is good i would suspect a faulty ecm or bad crank position sensor.

 

If the poster isn't comfortable tearing the engine down, used oil analysis will flag excessive copper levels too.

 

yeah you could do an oil analysis but typically i find them to be inaccurate. atleast wokring in a truck shop. every time i send one out for a caterpillar or cummins they always come back with... traces of coolant, traces of copper, etc.... im more of a fan of seeing a problem and then going from there. like unexplained coolant loss or oil pressure suddenly dropped to 20 psi from 40 overnight.