aa2001cherokee

Hey guys im very new here and i thought this was the best place to ask about my cherokee, so here i am. i recently bought a beat up cherokee that i would like to fix. i am a young kid and passionate about my car. so heres my problem. my jeep was broken with a brake and axel problem and sat for about 3 weeks. before those 3 week my oil pressure was always fine and my engine temp never even got up to 210, even after a couple hours of driving. this was also when the weather was a bit nicer here in illinois. i started driving it again and now my engine is getting too hot. it is running at about 220 to 230 never goes higher. i also have a small leak in my rear main seal, that i was going to fix but a different problem arose. before i drove i made sure i had plenty of oil. it also got changed about 1500 miles ago maybe around 2 months or so. so heres my biggest issue. when my engine is cool my pressure is oil pressure is high, thats what i expect knowing how oil viscosity works with heat. but as my engine get hotter my oil pressure rapidly drops. eventually when it gets to about 220 to 230 degrees i will be driving around at about 1800rpms with about 20psi, but what scares me the most it goes down to zero. it eventually dropped to zero when i was driving down the highway. i just threw in a quart fot the hell of it. when i got home i let the jeep sit and drained a little bit. WHAT THE HELL DO I DO?! Please help i have to fix these probs asap i have a week off of school and i need to get to work. thanks in advance.

ZINGGG

Firstly, the oil leak you speak of that's supposedly coming from the RMS may be coming from elsewhere. There are other areas above it (most commonly the valve cover and oil filter adapter) that can leak down to that area and mimic a RMS leak. Degrease your engine and find exactly where it's coming from before pulling the trigger on the RMS.

Secondly, you want to verify the oil pressure with a mechanical gauge and not base your readings off the gauge. XJ gauges have a tendency to be inaccurate and that is the most common gauge that is inaccurate.

Lastly, sounds like it may be time for some cooling system maintenance. What color is your coolant? I'd start with flushing the system and replacing the thermostat.

What year is your XJ?

aa2001cherokee

i have recently replaced my radiator. and flushed my coolant. my coolant was pretty brown. but i also know that oil leaks on cherokees are always coming from that 2 piece RMS. but sure i can flush it again for the winter and replace the thermostat. also by gauge do you mean sending unit the or the actual gauge? and yeah ill take it to my highschool shop degrease it and ill check it out. what spots should i be looking at? and lastly when i did my coolant flush i put back about 75 water 25 coolant to flush all the crap out nicely. and i will do the flush this up coming weekend. thanks.

cruiser54

The oil leaks ARE NOT ALWAYS coming from the rear main seal. Read this and save yourself some headaches and money.

　
I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.
Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking.
Many mechanics, friends, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?
A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.

Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.
First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$hit flows downhill".

Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.
Revised 9-15-2012

cruiser54

Get a new thermostat in it for sure. Use only the one from the dealer 83501426 if you want to change it only once.

aa2001cherokee

alright see i understand the where you guys are coming from with the thermostat. but can my oil pressure really drop so low just from one of those leaks?

cruiser54

First off, you don't know if you have accurate oil pressure readings. Not til you check it with a manual gauge.

What brand of oil filter are you using?

Oil pressure sending unit and oil filter adapter seals can cause a little loss of pressure. Nothing else that was mentioned in the write-up can cause pressure loss, only leakage.

bigbadon

You said that you are running hot after a coolant flush? Hot temps will definitely affect oil pressure at idle. Did you burp all the air out of the system?