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2000 Jeep Grand Cherokee Low Oil Pressure

don4844 don4844
New User | Posts: 2 | Joined: 07/10
Posted: 07/01/10
03:04 PM

I have 2000 Jeep Grand Cherokee 4.7 L V8 with 95,000 miles.  The problem I am now having is that when I start the engine the oil pressure is at 40 PSI and run the car for 3 to 5 miles the pressure will begin to drop to zero and the warning light will come on. If I continue to drive another 2 to 4 miles or about 5 minutes, the pressure will slowly rise back to 40 PSI and will stay there until I turn off the car and let it cool down. I recently, but prior to this problem, I had the oil and filter changed at a Valvoline Service Center. Any ideas of what may be causing this problem and a recommended solution?


waynep7122 waynep7122
Addict | Posts: 4547 | Joined: 08/09
Posted: 07/01/10
05:21 PM

there are several things to check.....

if the engine oil has coated the inside of the engines and its blocking the oil drain back holes..... keeping all the motor oil up around the cams in the valve covers...

this has happened.. on other motors....

if you have had somebody do an engine flush.. where they put solvent into the oil... and started the motor.. it can wash the grime off the crankcase walls and clog the oil pick up screen....

this also has happened many times...  

one thing that has happened to the 6 cylinder versions...   the oil pressure switch needs to be removed and replaced...  but while you have it off...  disable the ignition coils... and crank the motor with the sending unit out..

this lets the oil pressure to push out any solidified oil that sometimes gets behind the oil pressure sending unit.. the opening in the face of the unit is tiny..  and easily clogged...

harbor freight tools offers 2 different oil pressure test gauges... one with adaptors.. one without..  these can be screwed into the oil pressure switch passage.. but usually a tee is used.. as the system uses 2 of the 3 wires to power the electric fuel pump on many models....


one more thing...  i have with the ignition switch turned off... using a remote starter switch hooked directly to the starter motor..   i have cranked the motor with the oil filter off to look at the amount and flow the oil pump puts out ...


one last thing.. any filters you take off.. have it cut open...  examine the element .. make sure it did not break up.. this has happened also...  with some well known filters...  the paper element is rigid..  when the engine is revved with cold oil.. the oil pressure can damage the element.. causing pieces to break off and get pushed into the oil galleys...   this does not sound like your problem..


so....  clogged drain back passages...

check the oil level....  note the exact level...

start the motor...   let it idle for a few minutes.. keep an eye on the oil pressure gauge.. if it starts to drop shut down the motor....

after a few minutes shut off the motor... as soon as it stops.. pull the dipstick.. wipe it off and get a fresh reading..

then do it again.. as fast as you can..     see if the oil level was lower than expected when you first checked it..  then is getting fuller and fuller as you keep checking.. this would indicate clogged drain back holes..

it makes a huge mess.. but the easy way to clear out sludge is with a long air nozzle..  but it blows off everywhere..  this is after you pull the valve covers...  

don4844 don4844
New User | Posts: 2 | Joined: 07/10
Posted: 07/05/10
06:27 PM

Dear waynep7122,

Thanks so for the information.  Before starting your recommendation I went back to Valvoline and requested that they install a new oil filter, which they did today. So it's to soon to tell if this corrected the problem. I will start fresh tomorrow morning to see if the problem is still there. I am keeping my finger crossed.

What I would like to ask my problem unique?  I would think normally if you have low oil pressure it would stay low as the car heated up.  In my case the oil starts okay (40 PSI) when cold and drops after 5 to 10 minutes of driving and then the strange part is that it gos back to normal after another 5 to 10 minutes of driving or when at operating temperature. I wouldn't think that it was the engine itself, but either the sending unit or clogged drain holes? But I am no expert!

Some more information for you: I am the original owner and have always changed the oil and filter every 3000 to 4000 miles. The car engine sounds great (same as the day I drove it form the dealer in 2000.  And most important I love my Jeep.  

Thanks again for your help,

waynep7122 waynep7122
Addict | Posts: 4547 | Joined: 08/09
Posted: 07/05/10
07:08 PM

i know you are not alone...

you have to copy and paste the entire link into a new window...

or do your own search for jeep low oil pressure.. in the search link on the same line as where you log out at..  

waynep7122 waynep7122
Addict | Posts: 4547 | Joined: 08/09
Posted: 07/05/10
07:14 PM

1999 Jeep Grand Cherokee Oil Pressure Problems, Please Help!

New User | Posts: 1 | Joined: 09/08 Posted: 09/04/08
10:14 PM
1999 Jeep Grand Cherokee 4.0 242 cubic inches, oil pressure is good at a cold start and when engine warms it drops to the point that the check gauges comes on.  When you give it gas the oil gauge comes back up.  The engine has been completely taken out and completely rebuilt, replaced pistons, rod bearings, main bearings, oil pump, timing chain, cam bearings showed no wear, micked them and they were well within spec.  Reassembled engine, plastic gauged all oil clearances were within limits, but problems still persists.  In fact didn't change anything.  Checked oil pressure with mechanical gauge and it shows no different reading then the one on the dash.  Engine sounds fine, no rattles, ticks or bumps, let it idle for 45 minutes with oil pressure gauge at 0 and still no rattles, ticks or bumps.  Would like to know if anyone else is having this problem or if anyone has found a cure for this.  Thanks in advance!  

New User | Posts: 6 | Joined: 08/08 Posted: 09/05/08
02:38 PM
Try a heavy weight oil 20w50w My Trans Am shows low oil pressure when hot also and I had the engine rebuilt with a new oil pump but I should have bought a high pressure oil pump not a high volume pump. So I went to the thicker oil and at least the oil pressure light dosn't come on.  

New User | Posts: 1 | Joined: 09/08 Posted: 09/10/08
04:31 PM
I am having the EXACT same problem.  No heavy oil does not fix it.  After reading your post I can only assume that a portion of tubing has become blocked somewhere in the block.  I just began looking at oil pumps and other parts assuming it was the pump.  Then decided to google for information and found this.  I have not talked to anyone locally who has experienced the problem.  i have noticed that after an oil change with fresh new oil the problem usually goes away for a little while.  however this period of time varies greatly.  If you have discovered anything else about this please let me know.


New User | Posts: 1 | Joined: 10/08 Posted: 10/05/08
06:19 PM
I am haveing the same problem I havent changed the oil in 4 monthts I thought that was the problem so I bought royal purple 15w40 it worked fine for about an hour then I came to a hard stop and it droped to zero.
If anyone knows what the problem is please let me know
thanks.. John  

New User | Posts: 1 | Joined: 10/08 Posted: 10/07/08
02:45 PM
My  problen with my '99 Jeep Laredo is when i start it the pressure stays at zero until it warms up even though the oil is fine.... any suggestions???  The warning light alarm is driving me crazy!!  

New User | Posts: 1 | Joined: 10/08 Posted: 10/20/08
06:47 PM
10-20-08 I have a 1999 Jeep Grand Cherokee just turning 199000 miles and the oil pressure dash gauge just did the same thing. There doesn't seem any problem with the oil getting through the engine.  

New User | Posts: 2 | Joined: 10/08 Posted: 10/21/08
10:32 PM
My point of view comes from a machinist and also working in the automotive engine rebuilding line of work.  I have seen on jeep 6 cyl engines the connecting rods become out of round and at the parting line (the macined surfaces) and are egg shaped. feeler gauges wont show this condition nor will plastigauge each of these methods only show the overall average not the exact oil clearances at all positions of the connecting rod.  We found that macining the connecting rods round and puting the oil clearences on the minimum specs. it had great oil pressure.  

New User | Posts: 4 | Joined: 11/08 Posted: 11/13/08
05:22 PM
i just started having the same problems with my 2001 jeep grand cherokee at idle the pressure is 0 driving it's normal any answers please help  

Enthusiast | Posts: 652 | Joined: 10/08 Posted: 11/13/08
11:21 PM
2001 jeep 6... try changing the oil pressure sending unit below the distributer...   use some spray cleaner to clean the area around the sender first..   then with the coil wire unplugged... crank the motor over for a few seconds with the sending unit out..  this will clear the oil galley leading to the sending unit...

you might also check the grounds from the battery negative to the engine and the body....

oh... and it takes a special deep oil pressure switch socket to change the sending unit..   not pliers...  pliers can damage the crimp and shorten its useful life . (most chain parts stores have that tool for rent)  

New User | Posts: 2 | Joined: 11/08 Posted: 11/20/08
07:56 AM
I am having the same problem with my 2000 jeep grand cherokee laredo with the oil pressure gauge.  Just got my oil changed a few weeks ago, have only gone abot 6,000 miles, and believe it or not, there's less than 60,000 miles on the car.  But the warning light beeps when it comes up and it's driving me crazy, car drives fine.  Gauge goes to zero if I idle or decelerate, and the light beeps and comes on, but I don't feel anything different in the car.  When I accelerate or maintain speed the guage comes back up and maintains, the light goes off, and everything is fine until I decelerate or idle.  Did anyone with this same issue ever figure out what the problem is?  Is the car safe to drive?  

New User | Posts: 2 | Joined: 11/08 Posted: 11/21/08
03:19 PM
Me again, I got sick of the infernal beeping after one night.  Went to the dealership I bought the car from.  Cost $56 for the diagnostic test to be done and I found out the problem is the "Oil pressure sensor switch".  That will cost $142 for parts and labor.  But there is nothing wrong with the car itself which I'm thrilled about!  

New User | Posts: 1 | Joined: 11/08 Posted: 11/24/08
09:25 PM
you need to put a factory oil filter on it  

User | Posts: 140 | Joined: 11/08 Posted: 11/25/08
01:30 AM
A quick check is to make sure the o-ring thingy that seals the oil pickup tube where the pickup plugs in isn't damaged.  

John R. seeking for the best maintenance help on Toyota Corolla cars..

New User | Posts: 1 | Joined: 12/08 Posted: 12/30/08
08:10 AM
I am having the same problem and my 2000 jeep grand cherokee laredo is in the shop as I write.  I will let you know what comes of it.  

New User | Posts: 4 | Joined: 11/08 Posted: 01/05/09
08:15 PM
thank you all for your input the problem was the oil pressure switch now i lost my over drive any advice on what the problem could be  

New User | Posts: 1 | Joined: 01/09 Posted: 01/06/09
03:22 PM
I have a 2001 Cherokee and having the same problem.

Are you talking about an "oil pressure switch" or "oil pressure sender" or are they the same?  

New User | Posts: 1 | Joined: 01/09 Posted: 01/09/09
05:20 PM
I have had the same problem after replacing the sending unit. I have been driving it that way for over a year.  

New User | Posts: 1 | Joined: 01/09 Posted: 01/12/09
08:52 PM
I have 1996 with 4.0L with 87,000.  I just changed the oil and now my oil pressure gauge does not increase no matter what RPM.  I can tell the gauge gets power because it moves when I turn the key.  It does not fluxuate at all.  

New User | Posts: 1 | Joined: 11/09 Posted: 11/15/09
02:05 PM
I am haveing the same problem outside changing my oil thinking this isn't the car now stars some times..thinking it's the sensor im goind 2 the dealer..    

New User | Posts: 2 | Joined: 03/09 Posted: 12/07/09
10:48 PM
Hi thread I have similar problem except my oil gauge goes up when I step on the gas
As if the pressure is too high will your method help with this problem  

New User | Posts: 1 | Joined: 12/09 Posted: 12/11/09
07:46 PM
I had the issue with my 01 Grand Cherokee where the oil pressure dropped unless the accelerator was pressed. This only happened when the temp outside dropped below 55.  I took it to a repair shop and had them change the sending unit.  This did not resolve the problem and in fact made the oil pressure go down when the accelerator was pressed.  After a couple of winters parking the car, I bought another sending unit and put it in.  Once again no fix.  I read the post about blowing out the oil galley and tried that.  A clump of stuff came out and then clean oil.  After replacing the sending unit I took a drive in 26 degree weather.  I am happy to report that this resolved my issue.  I have seen many posts about replacing the sending unit but this is the first place I have seen the info about blowing out the oil galley.  Thank you.  

New User | Posts: 1 | Joined: 02/10 Posted: 02/08/10
08:08 PM
+1 on blowing out the oil galley.  Just did that this morning, and my oil pressure is back where it used to be.  I'd give this a try first, as it doesn't cost you anything to try.  

New User | Posts: 1 | Joined: 02/10 Posted: 02/14/10
06:15 PM
2000  grand cherokee, 4.7. the oil pressure dropped to 0 and i ran some sludge cleaner through it. i put in new oil and replaced the filter. it took care of the problem for a few hours. i checked the oil pump and its working so i then replaced the oil pressure switch and everything seemed fine. the oil pressure read around 40 psi. but when i take off the oil pressure drops to 0 again. at idle the pressure stay around 40  and when the rpm's are high its also fine but i cant go 30-65 mph and cruise without the oil pressure going to 0. any ideas. thanks for any advice if you got it.  

New User | Posts: 3 | Joined: 03/10 Posted: 03/03/10
04:48 PM
Well this is going to shake things up. I have a Ran 2500 with a Cunmmins diesel that does the same thing. Runs fine down the road but when you hit a light the oil pressure drops off to 0. I have been a diesel mechanic for 20 years and I know what an engine sounds like when oil pressure drops to 0 and that is not the problem, Tried a new sensor 42 dollars little better but after a while same thing. Shorted out the sensor about 40 thousand miles ago so the bing bing would stop.  Now the fuel gauge is doing the EXACT same thing when gets below 1/2 tank. Shows empty and starts binging.
GOOD ENGINE TRUCK IS JUNK.Pulls a camper good though  

New User | Posts: 6 | Joined: 03/10 Posted: 03/24/10
06:28 AM
I can't get the sensor off to get to the oil sending unit. Any help/ hints would be greatly appriciated. Thanks.  

New User | Posts: 2 | Joined: 03/10 Posted: 03/29/10
08:02 AM
There is a little tab you lift as you pull it off. (Not up or off...just up a little)  Its black like the everything else so feel it with your finger.  It will snap back into the unit after you push it back on and click so you know it is back in place properly.  

New User | Posts: 2 | Joined: 03/10 Posted: 03/29/10
08:03 AM
What is the little red button on each side of the electrical switch that attaches to the sending unit?  It clicks from one side to the other.  

New User | Posts: 6 | Joined: 03/10 Posted: 03/29/10
10:07 AM
I got the red tab out. I can't get the sensor out now. Pain in my butt.  

Guru | Posts: 1096 | Joined: 08/09 Posted: 03/29/10
11:16 AM
you will have to copy and paste this link to see it...

but this is a picture of a oil pressure sender for a 2001 jeep GC 4.0

you depress the tab on the connector to allow you to pull the connector back.      i a thinking that the red tab you have removed is the locking tab   to prevent the accidental release of the connector..    so the red cross tab has to come out.. then there is a square tab to push in or squeeze while pulling on the connector body..    then you can unscrew the oil pressure switch with a wrench or deep socket..     some models take a special oil pressure switch socket that is available at most parts stores...  
Edit Post  
New User | Posts: 6 | Joined: 03/10 Posted: 03/29/10
11:37 AM
Thanks Wayne, the top tab is broken off so I didn't notice it.  

New User | Posts: 6 | Joined: 03/10 Posted: 04/04/10
07:51 AM
I cleaned out the gallery, and it didn't help. Any other ideas?  

New User | Posts: 6 | Joined: 03/10 Posted: 04/05/10
07:56 PM
Now my pressure went from almost nothing to right under 80 psi after cleaning the gallery.What is the ideal oil pressure? I'm hoping it is just giving me a false reading. It will stay right at 45-50 after I drive it for about 30 minutes. Any ideas?  

New User | Posts: 1 | Joined: 04/10 Posted: 04/28/10
04:50 PM
i am having oil pressure trouble also, i have a 2002 wrangler, and my pressure droped to below 30psi, my oil was just changed with royal pupple 5w30, so oil level wassnt low, i did get some lifter clatter, but then it went away and press came back up. i used a frame oil filter and was told to change it because the frame filters have been collapsing under press, so i put a k@n filter in.  the oil press did come back up better than before, but its still fluxing at idle.  

mrmac731 mrmac731
New User | Posts: 2 | Joined: 09/10
Posted: 09/09/10
09:13 AM

well guess what I have an o2 grand cherokee with 4.7 v8 doing same thing, when i start it gos right to 40 psi, if the motor gos over 2000 rpms the psi drops to 0. Could someone tell me how i would clean the oil galley, I know its not the oil pump the motor runs way to strong, and i have replace sending unit THANKS  

waynep7122 waynep7122
Addict | Posts: 4547 | Joined: 08/09
Posted: 09/09/10
05:53 PM

pick up a new oil pressure sending unit...   for the gauge or for the light...  they are different... buy the proper socket for the oil sending unit.. there are several different ones... i have 4 different ones in my tool box... they keep getting deeper...

disable the ignition system ,   so the engine will NOT start..( test to make sure it won't start before taking the oil sending unit out..  the oil will be everywhere in seconds if it starts...)

clean the oil sending unit area with some brake cleaner or carb cleaner spray...

use a drain pan to catch the overflow of cleaning spray.

disconnect the sending unit wire....   use the socket to unscrew the oil sending unit and take it out...

have someone crank the engine for a few seconds.. while you watch the oil flow from the opening..   be sure to block it with your finger if it puddles .. you don't want it draining back into the motor.. i don't know where the sending unit is on a 4.7..

screw in the new oil sending unit...    then clean up the oil spill...   DO NOT Clean it with the sending unit out.. you might get dirt into the oil galley...

plug the sender back in...     hook up the ignition or what ever you did to stop the engine from running..   DO NOT JUST PULL the spark plug wires ...

there are several ways to disable the ignition..

check the oil level.. top it off... if its more than half a quart low...  and start the engine...

the oil pressure switch has a TINY opening for the oil to flow through  this stops the gauge from swinging wildly... a single piece of dirt or a plug of sludge .. ( i have seen the plugs of sludge come out my self on 4.0 motors)   these can get pushed against the bottom of the oil pressure switch cutting off the oil pressure to it...

there have been problems with the oil pick up screens clogging on some motors ... this restricts the amount of fluid the pump can pull up from the pan...    

the first step is to clean the passage... get the plug of dirt out...   DO NOT INSERT anything into the passage... let the oil pump push it out...

use a new sending unit....  they are available in most parts stores... in stock ...  

mrmac731 mrmac731
New User | Posts: 2 | Joined: 09/10
Posted: 09/09/10
07:55 PM

Thanks i will give it a try as soon as i have the time, after i do so i will repost to let you know how it works out .  

Mellow_Yellow Mellow_Yellow
New User | Posts: 2 | Joined: 11/11
Posted: 11/07/11
03:24 AM

Hey guys, I just bought my first Jeep the other day.  It's a 2000 Cherokee Sport with 167k miles and I am having the same issue with the oil pressure going to 0 at idle but 40 at speed.  I am going to clean out the area by removing the oil sending unit and trying to start the car.  What is the best way to prevent it from actually starting for this process?  It was recommended NOT to simply pull the spark plugs.  

waynep7122 waynep7122
Addict | Posts: 4547 | Joined: 08/09
Posted: 11/07/11
09:04 AM

if it has a conventional distributer cap...

you have several options...   removing the coil wire from the center of the cap..   moving it away from the distributer..

you could also just unplug the wire from the side of the distributer... thats the cam sensor.. that should also stop the fuel injectors from spraying..

if you have the full length coil...  you could unplug the electrical connector from that..

just try cranking the engine before you remove the oil pressure switch..

if you have that many miles... and after you get done...  if you have noisy rockers with a 4.0 straight six motor..   you might want to also change the rocker arm fulcrums..

67754 Md
67782 Th  

Mellow_Yellow Mellow_Yellow
New User | Posts: 2 | Joined: 11/11
Posted: 11/07/11
05:02 PM

Thanks for the quick reply.  I'll give it a try Friday and report back if it solved my problem.  

rckozy rckozy
New User | Posts: 1 | Joined: 01/12
Posted: 01/26/12
09:53 PM


Ronaldbyram Ronaldbyram
New User | Posts: 1 | Joined: 07/12
Posted: 07/03/12
11:40 AM

I have a 2000 Grand Cherokee 2ith 225k miles the mote was rebuilt at 146k.  I have had the oil sending unit replace 3-4 times.  I keep the oil Changed every 3k miles.
my gage now shows 80psi at noral operation.  Just just 1000 miles from NC to Canada.
Discovered that when we started pulling a hill and the transmission jump into OD. the pressure dropped to 0 and the alarms go off. WHen you back off and the Transmission changes gear the presure comes back.

My mechanci saud it has to be the unit and the wiring harness?  THoughts?  

waynep71222 waynep71222
Guru | Posts: 823 | Joined: 03/12
Posted: 07/03/12
01:44 PM

yes .. it could be either...

it could also be a bad ground connection...  the ground side is HALF the CIRCUIT...

do you have a hand held digital volt meter.     these tests take less than 2 minutes to complete..

start the engine.. turn on the headlights...

set digital volt meter to 20 volts DC...

1.    measure NEGATIVE battery post to the Positive battery post...  14.1 to 14.8 volts is expected.

2.  measure Negative battery post to the ENGINE BLOCK..  0.04 volts is expected..

3.  measure Negative battery post to the BODY of the jeep..  0.02 volts is expected.

4. measure ENGINE BLOCK to the BODY... 0.02 volts is expected...

0.00 is not a valid test...   change the meter setting to 2 volts setting..    and retest

if you get more than 0.02 or 0.04 volts you have a bad ground... that the terminals need cleaning..

the battery negative is hooked to the side of the engine..

its also hooked to the body...

the engine is hooked to the body..

the fuel injection and the wiring harnesses are hooked to various grounds around the engine block and the body...   if any of these is dirty.. and it does happen.. you will get strange readings on your gauges..

what's happening.. is the sending unit has a variable resistor connection to ground..  if you have bad grounds.. you will have voltage differences you will see with the volts meter tests above...

these are JUST the first few tests.. there are tests at the individual ground connections for the harness..

the harness sections can be grounded in several locations...

left and center of the firewall above the engine...  

on the frame rails behind the headlights and grill..

inside the passenger compartment behind the left and the right kick panels are also ground connection locations usually for the dash board components...

if any of them are dirty.. you could have found your problem..

try the test..  digital volt meters start at 7 bucks.. but a 15 to 20 buck version will last you for years..

post your test results.. i will be able to advise you.. . also include which motor you have..  

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