Hi Jeepers,
What's up with all these issues with the 2000 Wranglers & Cherokees?? Between My Brother, my nephew & myself we have about 7 Jeeps. My Brother has a 2000 TJ & my Nephew has a 2000 Cherokee XJ. The TJ started in the winter with no heat. There was never an overheat problem, it just loss coolant over time. Then the oil pressure started fluctuating.(0 pounds at Idle) The XJ did the same thing with the coolant but didn't have the oil pressure issue. The XJ got a new cyl head & was good for about 6 months and it started losing coolant and now is losing oil pressure.
The TJ just had a new head, oil pump, oil sending unit installed & now still has no oil pressure at Idle. Both of these Jeeps are under 80,000 miles & have had oil changes done every 3000 miles. Neither have ever been abused or even off road with the exception of Camp Jeep twice(I know thats a cardinal sin in the Jeep world to not take them off road)BUT!!!
I read on line of hundreds of people having the same issues. When we contact Jeep they act like they have never heard of these problems. They say "Oh we've changed a few engines" but they don't know why. They just claim like it's the customer's negligence in that the Jeep overheated & caused the engine to fail.
4.0 Jeep engines are the most reliable I've seen. We have 2 that are both over 240,000 miles & run like new still!!!
Neither of the above Jeeps mentions had been abused in any way or neglected. There is clearly a factory defect in the 2000 4.0 engine & Chrysler needs to admit it & take care of their customers who are the most loyal of any manufacturer!! Any advise or hints appreciated.
Both the TJ & the XJ have failed in just enough time to make attemding Camp Jeep 07 impossible for both my Brother & his son. Camp Jeep only refunds 1/2 of the $300 spent to attend if cancelled so the $1500 invested into the TJ to attempt to repair it has another $300 loss added to it now.....  

I have a 2000 Cherokee Classic and having similar problems.  The coolant issue doesn't bother me.  Just check it once a week, put in some coolant if it's low.  The oil pressure though is bothering me.

Almost two years ago I took it in because I notice the psi at 15 or lower when idling.  The garage did a thorough check of the gauge and cleaned everything.  It didn't help the pressure.  They called Jeep for me and they were told that as long as the engine is seeing 13 psi when idling, you were good.

Now to present day.  While cruising on the freeway/interstate I am seeing 30 psi after the Jeep warms up.  And when I am idling, it is dipping below 10 psi.  I took it to a different garage (because I moved).  Now they don't do major engine repair, but talked around and looked at things.  They said it could be one of many things: engine fatigue, bad sending unit, bad pump, etc.  But they couldn't pinpoint it.  They suggested that I call Jeep and see what they would say.  Though from the above post I don't think I will waste my time.

Are there any suggestion out there?  Has anyone had this problem fixed?  And if so, what did it take to fix it?  

Well the following is certainly not a fix but a try to at least limp it along before just dumping out the $4000. for a new engine. After we changed the Head, oil pump & sending unit the collant issue seems to be fixed. The oil pressure issue still hasn't changed. We changed the oil again, added 20w50 this time & some Slick 50. Now we're running a massive 30 pounds of oil pressure at 55 mph & a moderate 10-15 pounds at idle. We're going to run it until it blows then probably drop a 350 Chevy V-8 in it. Then we wont have to worry about loss of oil pressure or coolant ever again!!  

"Then we wont have to worry about loss of oil pressure or coolant ever again!!"

Oh I've seen plenty of 350 Chevy's lose it... What are your plans for the new engine?

Glad to here that your engine is running at least, knowing the 4.0 it will probably last another 100,000 miles even with the low oil pressure... lol  

Hi,
On a related topic, has anybody ever removed a fan clutch from a 2001 TJ? I want to do this to put an electric fan in my Jeep. The instructions in my manual are not accurate. Any help?  

easy peesy man, there are four nuts holding it on, but you have too pull out your fan shroud to get it out without damaging stuff, then you put on some spacers, "if you dont put spacers, it wont tighten up enough", so you can put the four nuts back on to hold the pully on the waterpump, then you can mount and run the wires, and thermocoupler for your new elc fan. : ) get to free up some ponies.  

Have you had any luck getting this fixed or getting jeep to do anything? I actually had a 99 cherokee and sold it to get a minivan(more room for expanding family) but I missed my jeep and wanted it back so we found a 2000 with 100k and in great condition for reasonable priced but after buying it on the way home i noticed coolant low warning beeping so we stopped to put water in and then noticed the oil pressure was not staying up and the check gauges light keep coming on. We have put alot of money in to fix problem, such as, replaced cap on coolant, replaced oil sensor, replaced oil pump, replaced oil pan and all that stuff after we had put cleaner in it and changed oil twice but we are still having the same problems and everyone we have talked to says that they do not know what else it could be or how to fix this problem. I love my jeep and plan on staying with the jeep products because they have always been good in past but I would really like to get this fixed because i am scared if i keep driving it it will hurt something else and i can not afford to buy new car or replace anything else in my jeep. Any info or help would be greatly appreciated. I am desperate. thanks  

If I were you guys, I'd save all my reciepts for any work that you put into your motors....If there's a recall on this, you might be able to recoup your money.  

i have a 00 tj thats overheated (260+) because of a plugged radiator & prolonged hi speed, 3/4 of it cold to touch when steaming from cap.so flushed rust & junk from block & heater core (new rad) no overheating now but drinking antifreeze, i'm sure its a head gasket but no time to troubleshoot,(check plugs,compression,etc.) daily driver so add here/there.no oil pressure issues tho.  

I know a while back oil pumps were a porblem in most auto's. since the manufacturers of autos do not make oil pumps (farmed out to another company) but when the oil pumps are made they have a relief valvebuilt into the oil pump. it mainly consists of a steel ball and a spring (set to spring pressure to match oil pressure of pump.

so alot of oil pumps were manufactured with weak springs. after service they found that the spring would loose tension and would start to leak by the relief valve dropping oil pressure in the motor.

now chevy v-6 motor have a problem with using coolant because the collant runs through the intake. and the intake gaskets start to leak coolant to the cylinders and the motor just burns it off.

what happens is the operator doesn't realize there is a problem until the engine light comes on. by then it si too late the motor has over heated and taken out the heads. some like my wifes van she didn't have any heat last winter and I checked it to find no coolant. took it to the dealer and it had bad intake gaskets.


so my question is. does the jeep motors have coolant running through the intake manifold? would explain were the coolant is going. it doesn't loose alot. but over time as one person already said. check it once a week and add as needed.  

its probably a cycle started by an internal coolant leak (leaking head gasket) that lets coolant get into the oil. when the coolant hits the bearings it begins to destroy the babbit material in the bearings causing them to come apart. when the bearing clearances open up beacuase of the loss of their plating you lose oil pressure. thats why they have similar problems. they start to use coolant and then the bearings go and no oil pressure. changing the pump or anything in the oil system does nothing. the engine must be rebuilt to fix the problem.  

I know that the coolant will help eatt he bearings. that is why I asked if they had coolant running through the intake like chevies and fords do now on most motors.

the coolant leaks to the intake valve and burns it up. never had issue with oil pressure so you are more than likely right. getting into the oil. but I thought the one post said the oil was fine just low pressure?  

I also have a 2000 Jeep Grand Cherokee with the same coolant lose,oil pressure problem.To this point, I have replaced the sensor,replaced the oil pump with a 20% higher volume pump, and replaced the rod bearings  while I had the pan off. This Jeep has 133,000 miles,the pan had never been off, and the rod bearings had "NO Wear" to them. I figured the rods were fine because there was no rattle in the bottom even when the oil pressure bottomes out.So I dought the coolant is getting into the oil.The oil always looks good.It must be burning in the combustion chamber.So where is my oil pressure going? None of this made any improvment.The oil pressure still bottomes out when engine warm and idling. Any body got any idea? I checked a main bearing and it was fine. I wouldnt expect the cam bearings to be worn,without the other bearings having some wear.I would like to get to the root of the problem. I believe there is a flaw in these 2000 model 4.0 engines, and I wonder how many of us would have to band together to get Chrysler to do anything about it. Any ideas welcome.  

Hi all!  I have the same problem.  
A 2001 Cherokee with only 65k miles.  A couple of months ago I started noticing loss of coolant.  I did not see any leaks but did smell coolant sometimes after the motor was fully heated up.  Seems like every couple of weeks I had to refill the coolant reservoir.  A couple of times I had to also fill up the radiator.  I had no luck looking for leaks.  
Then, out of nowhere, the oil pressure started to drop once the motor was fully warmed up.  The gauge would drop to zero below about 1200 rpm.  

I took the car in to the shop and had them inspect the cooling system and oil pressure.
They could find no coolant leaks even with a pressure check.  They could find no oil pressure problems but replaced the sending unit just in case.  
There was new oil so no indication of oil/water.  Have to check that later.

I got the car back and not long after it warmed up again, oil pressure gauge dropped to zero.  Had to keep the revs up to keep pressure registered?

Has anybody heard from Jeep about this?  Does anyone know of a class action against Jeep?  Seems like this may be deserving of one.  

OK, has anyone used a mechanical gague to verify death?
I don't trust electrical gagues.
If you have 0 oil pressure, the lifters will be ticking like crazy.  It will go away when you revv it up to establish oil pressure if that is the problem.

If you have 0 oil pressure, you think you would have enough play in your bearings to hear it, thus causing the low oil pressure.  When you replaced the pump, did you clean the screen and pan well?  How about the gasket surfaces.  Air will really mess with the oil pump.

No, coolant does not run through the intake maniflod, at least on the inline motors. Never worked on a jeep V6 or V8.

If anyone has any more questions, I will try to help....  Email me at Benjorno@aol.com