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I just purchased a 2000 Jeep Grand Cherokee and drove it home to find the oil pressure after warm up drops so low the {idiot light} comes on. When I test drove the vehicle it ran fine and showed no signs of loss of oil pressure.I have changed the sending unit and have also replaced the oil pump. I have also plugged in a direct gage to find the same effect oil pressure starts high at cold start up at about 40 psi and as the engine warms the oil pressure drops. The Jeep has 120,000 miles and strats easily and seems to have plenty of power. Any ideas on what to look for or do next? Any help will be greatly appreciated  

I have a 2000 Cherokee Classic, which I have owned since day one.  I am having the same issues, but I haven't gone as far as replacing anything yet.  I have taken it to three different shops, and a Jeep dealer, and they all don't know what's wrong (though the dealer said that if changing the pump doesn't help then I am looking at a new engine).

I have read around quite a bit of others having the same problems with Jeep engines over 100,000 miles (mine is just over 127,000).  However, no one seems to have them die/seize up on them.  They all run well on the lower pressure.  Obviously this is not comforting news, but I have found out nothing further.

The only suggestion that I have heard is using a heavier weight oil.  But then what do you do when winter rolls around?  I am stuck too and would love to hear if anyone else has any other suggestions.  

If the problem is mechanical and you have replaced the oil pump then one would expect a journal bearing or lifter assembly is losing to much oil. This is considering the relief valve has been changed including the oil filter. The reason your dealer suggested a new engine is it would be expensive and time consuming to inspect all the bearings and the valve train. So you would taking a risk if you assumed it was the cam bearings.  

It has been almost 2 years since this happened to you. What was the out come???
My 2000 JGCL is now at 100,000 and the oil gauge is acting more like a tachometer.
If you read this any time soon email me with the results of your findings.
henthorns@comcast.net  

there are a bunch of people with this problem...


change the oil pressure sending switch...     use the proper oil pressure sending switch socket to do it..  some stores have tool rentals so you may not have to buy it...

the idea is also to clean the area of the threads with brake cleaner first... (Before you take out the old sender)  then if you jeep has a coil.. unplug it...  with the sender out.. crank the motor over for a few seconds... this lets the oil pump push out any oil and buildup from the pressure passage...  put the new unit in...

you might also want to if you have a 4.0L motor ... replace the rear PCV unit..  the rear elbow on the valve cover... and the pair of thin nylon vacuum lines to it.. both available at jeep dealers.. the vacuum hoses are about 16 bucks last time i got them...  i have forgotten how much the rear fitting is...

turn it left about a quarter turn to get it out...  

what happens is the tiny vacuum hoses clog with oil and carbon.. preventing the crankcase vapors from being burned.. this can build up some pressure in the crank case...  usually it blows out into the air filter housing ... messing that up...

the lines come taped together... don't tear them apart..   they do fit...

best of luck... and this usually does fix the problem...  

i have the same problem with my 3.9 dodge. plenty of presure when cold but drops when warm. i have tried oil additives but nothing works any advise form you would be great.thanks. please e-mail mattjoly@hotmail.com  

I have a 1995 Grand Cherokee Laredo, and have the same problem.  It started when I had a tranny leak a while back, I had to have a mechanic replace the tranny twice(first replacement was a dud) then it worked fine for a while, then started leaking engine oil out the main seal(The one between the engine and tranny), oil pressure stayed fine as long as I kept the oil level up.  Then I decided to see if the bolts connecting the tranny to the engine were tight to find out that I could actually loosen the main bolts with my fingers, so I tightened them down as hard as my hand wrench let me, hasn't been leaking since, but now my oil pressure gauge acts like a tach, dropping to slightly above 20psi at stop light(but stable), then when I accelerate it goes to a little above 40psi.  Right now the problem seems like it's correcting itself.(The pressure doesn't drop as low as it use to)  

My jeep just went over 100,000 miles and Ive been having some problems with it and one of them was the oil pressure. When i sit at a red light or in park the oil pressure would drop to 0 followed by the check engine light.

The one thing i learned about Crysler, Jeep and Dodge products is everything is ran with a sensor.i just changed my Oil Pressure switch this week and Ive had no problems since. The other one i replaced was the coolant temp sensor because it was reading that my jeep was over heating but the sensor went bad. You will also see the same thing with the Crankshaft Position Sensor, which is tricky, because it could be a false read because of the Camshaft sensor too.

hope this helps  

i just  went on this sight and have the same problem and jeep runs fine  but have oil preasure issues when warm,do you still have the jeep and did you fix it  

couteret123:
I just purchased a 2000 Jeep Grand Cherokee and drove it home to find the oil pressure after warm up drops so low the {idiot light} comes on. When I test drove the vehicle it ran fine and showed no signs of loss of oil pressure.I have changed the sending unit and have also replaced the oil pump. I have also plugged in a direct gage to find the same effect oil pressure starts high at cold start up at about 40 psi and as the engine warms the oil pressure drops. The Jeep has 120,000 miles and strats easily and seems to have plenty of power. Any ideas on what to look for or do next? Any help will be greatly appreciated

have you fixed the problem and if you did what did you do  

scooter13:
I have a 2000 Cherokee Classic, which I have owned since day one.  I am having the same issues, but I haven't gone as far as replacing anything yet.  I have taken it to three different shops, and a Jeep dealer, and they all don't know what's wrong (though the dealer said that if changing the pump doesn't help then I am looking at a new engine).

I have read around quite a bit of others having the same problems with Jeep engines over 100,000 miles (mine is just over 127,000).  However, no one seems to have them die/seize up on them.  They all run well on the lower pressure.  Obviously this is not comforting news, but I have found out nothing further.

The only suggestion that I have heard is using a heavier weight oil.  But then what do you do when winter rolls around?  I am stuck too and would love to hear if anyone else has any other suggestions.

our 2000  has 118000km and is in mint ,it is a classic and runs good  and when it gets warm at a light it  or the oil light comes on and goes back up when we start driving,i just cant see it as a internal as the engine sounds smooth,what did you find out  

navyboi23:
My jeep just went over 100,000 miles and Ive been having some problems with it and one of them was the oil pressure. When i sit at a red light or in park the oil pressure would drop to 0 followed by the check engine light.

The one thing i learned about Crysler, Jeep and Dodge products is everything is ran with a sensor.i just changed my Oil Pressure switch this week and Ive had no problems since. The other one i replaced was the coolant temp sensor because it was reading that my jeep was over heating but the sensor went bad. You will also see the same thing with the Crankshaft Position Sensor, which is tricky, because it could be a false read because of the Camshaft sensor too.

hope this helps

interesting,we have the same problem,is your jeep still okay with the oil preasure as your method seems cheaper than a motor,our jeep classic is mint and sounds smooth when it runs