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Jeep Cherokee Grand Cherokee Engine and Performance Problems



  • ehuffehuff Posts: 4
    I have a 2000 Grand Cherokee with the 4.7 engine and 66,000 miles. Recently, for the first time the "check engine" light came on. The engine code indicated I had a misfire in cylinder 3. The coil and plug for that cylinder checked out O.K., but the compression is less than half that of the other cylinders. However, the remaining cylinders have variations of as high as 25 lbs./in. Mechanic tells me that bad cylinder heads are very common on this engine and that they probably need to be replaced. Has anyone else had such a problem?
  • tuggajbtuggajb Posts: 646
    have 2000 grand with 4.7 and have 156000 miles with no trouble have to do wet test on cyl that is low after you add oil and retest if reading goes to normal have bad rings if stays low then have head problems if check engine light came on could be computer prob
    the computer is mounted on the fire wall on right side behind the ac aculumater i had croaked connections there from water off aculumater cleaned greased OK now
  • ehuffehuff Posts: 4
    Thanks for the reply. Sounds like the problem is in the head(s). I squirted some oil in cyl. 3 the last time I checked the compression. Compression rose only 5 lb. (from 59 to 64). Question seems to be whether can be solved by valve job or if the heads actually have to be replaced. Obviously the latter is MUCH more expensive. However, I've received no other response so it looks like there is no widespread defect regarding the heads. Can't totally discount the computer problem because the check engine light has been off almost all the time for the last several weeks but there definitely IS low compression in cyl. 3 so it seems unlikely the problem is in the computer.
  • tuggajbtuggajb Posts: 646
    I would remove valve cover on that side and make sure that lifter was moving the valves on that cyl. could be lifter bad or cam lobe worn. sure would rule all other posablities out before i remove a head am the type that starts on the easey things first work tword the hard parts
  • ehuffehuff Posts: 4
    Makes sense to me. That'll be my next move.
  • hey i have an 91 jeep cherokee sport and it has a clank sound it the engine i think that it is a rod but i am not sure and i was just wonderen if any one else has had this prob that could help me friend said that it happend to a guy he new and he just drove it then about 30 miles later if busted and he had to get a new engine so i was wonderen if it is some thing worth tryin to fix or should i just put a new engine in it when it dies
  • well the sound is coming from the top end of the engine and it goes with the rpms and i think that it is just one cylinder the sound is like some one is hitting a hammer on the inside of the engine i know i sound like a dumb [non-permissible content removed] but if anyone can help me out with a answer on how to fix it if they have had prob i would appreciate it.....
  • tuggajbtuggajb Posts: 646
    might have broken valve spring not to hard to change that don't even have to remove head

  • tuggajbtuggajb Posts: 646
    if from top end probly not rod
    remove valve cover and look see if broke valve spring
    what engine you have 4.0
  • yeah it is a 4.0 straight six h.o.
  • lunghdlunghd Posts: 61
    Flex in motor was allowing the CPS to be shorted out & causing the ECU / engine to lose timing. CPS is a very, very common issue for these engines. Someone must have had this motor out in the past & not torqued it back correctly.
    Flexplate bolts coming loose are a common problem but not the motor to tranny bolts.

    Motor & tranny mounts are ready to be replaced after that many years... not too hard of a job and there are alternatives to the stock mounts.

    For a detailed "how to" on changing the mounts you can check out my On-Site Tech index at Another Freakin' Jeep Cherokee Website
  • well i removed the valve cover and none of the springs are bad it looks like it is all going like it should but on second cylinder back the clank is going with the second valve from the front on on the cylinder it is the only one that goes with the clank so are you still sure that it could be the flexplate bolts being loose and to be honest i am really not quite sure what you said like i dont know what the CPS is or the ECU or Flexplate. i am only sixteen so i am not sure what it all is but i have some clue to what is what but if i ever get this fixed i would like to learn more about you cheap lift kit that you did on that jeep of yours i think that is perfect for me if i get through this prob
  • lunghdlunghd Posts: 61
    Ok - I think I missed a few posts along the way but let me see if I am following you... Sounds like a hammer on the inside of the engine?

    This sound goes along with just one of the #2 cylinder's valves? If it is ONLY following ONE of the two valves is is more than likely a stuck lifter and not so bad... could also be a leaking exhaust manifold gasket...

    Hammer-like sounds imply a bad rod bearing. If it is a seriously solid 'CLANK / KNOCK' sound then it is likely to be a bad rod bearing or piston pin. It's hard for me to tell based on what you've described above so let's try this:

    Does it become more pronounced at higher revs?
    Does it get worse or diminish as the engine gets warmed up?
    Is it a solid 'clank/knock' or more of a 'tick/tap' sound?
    If you have an oil pressure guage... what's your pressure cold / hot? (Don't run it to get hot if it's really bad.)

    If it is more of a 'tick/tap' sound then you can try running some Marvel Mystery Oil in your engine oil plus a small amount mixed with your gas as well. (Just follow the label directions.) Marvel Mystery Oil is a great product - been around for ages & will help loosen a stuck lifter / valve. I had a stuck lifter on my 90 XJ when I got it about 7 years ago and a few weeks of running this freed it up never to get stuck again. It may take a couple of times using it with your oil changes to free up a badly stuck lifter. If your lifter has collapsed completely it will not fix it... Post back & we'll go from there!
  • ok yeah you have read what all that i have put

    It stays the same with higher reves but they are more constant with the motor , But i just started it today and it wasn't as loud of a tap now it is more like a combination wrench is being hit on the inside not a hammer
    And it starts go away at about 1 and 3/4 rpm but by 2 it is gone and when it hits three it starts to have this kind of whining sound and i haven't gone above that
    and the pressure gauge is at about 60
  • lunghdlunghd Posts: 61
    Sounds like a combination wrench? :P ( A ratchet??? ) I think I get ya. If I'm not understanding - please correct me!

    " SOUNDS LIKE " a sticky lifter but get a second opinion from an old neighborhood wrench you may know just to be sure.

    Assuming it's a sticky lifter: IE, if it's NOT a hammering/knocking sound that has a deeper sound... but is more like a ticking / tapping then try the Marvel Mystery Oil per directions on the bottle.

    SO LONG AS THE ENGINE ISN'T ACTUALLY KNOCKING... run it a few weeks, change the oil & filter & do the Marvel Mystery Oil thing again. You may have to repeat this again but it usually clears it up in a few weeks of running the motor.

    I did this a few times & it cleared up my sticky lifter. MMO is great stuff - glorified tranny fluid but does the trick!

    If your oil has been neglected in prior years the MMO will cause the oil to get dirty faster as it loosens up the varnish build up so be prepared to change the oil a few times in the next few months depending on your miles driven.

    AGAIN - if you have a knocking rod... this is NOT the way to fix it! Get that second opinion from a friend or neighborhood wrench...


    Link to my site:
    Another Freakin' Jeep Cherokee Website
  • when i said combination wrench i mean the wrenches that have a box on one side and then an open end on the other

    And for this MMO i have to drain the oil in it now put that in and then just run that and you think that it will stop and if it doesn't just change the filter and do it again

    But i will still go ask someone that knows what they are talking about also and if he thinks it is a sticky lifter i will try it
    but i will get back to you and tell you what he says and the prob might get figured out
    thanks a bunch for given some knowledge this way most people would just say what ever
  • lunghdlunghd Posts: 61
    Glad to help if I can! Just hope I can save you some $ with a cheap fix instead of having to open the motor up.

    Yes, definitely get that second opinion on the sound just to be sure. The sound you're describing sounds more of a metalic 'tank' sound, like a wrench striking the block than the 'tick-tick'tick' a lifter makes. Lifters can be pretty noisy - pushrod can be flopping around a bit if it's fully collapsed (which MMO will not fix...).

    No, you don't have to drain the oil now unless it's already past time to change it.

    Get that second opinion on the sound first... but if it's a lifter you just add the MMO to your oil now & run it until your oil change is due... THEN change it. It's all on the bottle.

    If you still have a sticky lifter, add it again. In my case it only took a couple of times adding it and no problem since.

    Again... have that noise confirmed as a bad lifter first.
  • ehuffehuff Posts: 4
    Thanks again. I'm out of town until Sunday but I'll be checking this out as soon as I return home.
  • hi

    my 4.0L jeep is running quite hot when idling (almost three quarters on dash) and stops going up when the AUX fan comes on. why won't it come on earlier? and when in motion drops down to under half (100 deg cel.). i changed the thermostate and flushed the radiator. i live in a hot climate is it just the radiator is to small for my missions.? or maybe this relay switch i read about. where do i find? is it a big job??
  • hi

    could be wheel bearing or hub. if you swerve the steering wheel back and forth like a mad man dose the noise come and go?
  • when i start my Jeep the oil pressure is a little lower than normal, as it warms the pressure drops, eventually to zero and the check guages light comes on. When I accelerate the check guages light shuts off and the pressure rises slightly, only a little bit! I have plenty of oil, and I had it changed 3000 miles ago. What is my Jeeps problem?
  • dsmansdsmans Posts: 10
    I have a 2000 Jeep GC and have just experienced the same problem. Today was the first time it dropped to zero however, and the check guages indicator came on. I was told before from Valvoline that a wire was off and they put it on, but the sending unit will have to replaced eventually if the problem persists. I will have to have the dealer confirm this week.
  • dsmansdsmans Posts: 10
    Ok, this is dsmans again. First I want to thank all that have commented on this particular problem.

    On 2/18 I wrote I had experienced the sensor problem. Since then, I have bought it to the dealer. They had the car all day and I called at 4:30 that aftrnoon only to find out that the sensor was checking out fine and that I had no pressure. What they then told me is the next step is to drop the pan and go in and assess the damage my engine has suffered. The beginning price to drop the pan began at $483. Secondly, most likely I was looking at getting a new engine. I said stop right there, I'll come pick it up and get a second opinion. After reading the comments here, I realized that my engine is fine, my oil is clear, I have no knocks, pings, or smoking, car running hot et al. I bought it to a AAA rated local autoshop and they replaced the sensor and the pressure was reading where it should be after idling. If it does go down again, they suggested, as long as the engine is fine, not to worry about it too much. I'd spend more trying to find out what the problem is.
  • I have the same exact problem with my 97 tsi. I replaced the cap, rotor, crank position sensor, cam position sensor, fuel pump, sparkplug wires, sparkplugs, ignition coil 2 times, air filter, motor mounts and it still giving me the same problem.
  • I have a 1995 6 cyc w 145k miles and had wide swings in oil pressure when driving and at idle. Pressure sensor internal membrane had tear and needed replacement, now working fine. Oil pressure test at 3k rpm's was fine but at idle was lower then factory spec, meaning some internal oil passage blockage. My mechanic recommended running some oil cleaner/flush thru engine before next oil change to dislodge internal debris which happens in every engine. Once a year this is what he recommends as routine way to keep clean.
  • rinomcbrinomcb Posts: 1
    So my oil pressure gauge on my '95 GC was doing much the same as many have posted here. Now I've replaced the sensor and my oil pressure gauge is reading zero - all the time! Do I need to reset a computer or something? Please advise.
  • cpb2cpb2 Posts: 6
    I have a 98 Jeep Cherokee 4.0L with about 85K miles on it. After starting normally, it runs and drives normally for about a minute, then it starts to misfire and won’t handle a load for about 45 seconds. After that, it drives fine until I shut it off. The problem happens even when the engine is fully warmed up, if there is a 15 minute or so cooldown period. If I stop enroute, say for gas, no problem. When the problem is occurring, I can rev the engine OK (manual trans), but cannot load the engine until it “clears”. If I watch the RPMs when I first start the engine and just let it idle, you can see the change from about smooth 1000 RPM to an erratic 250-750 RPM, then a surge to about 1200 RPM back to a smooth 750-1000 RPMs again. Almost seems like a timer-based mixture change or failed sensor bypass. If I attempt to “drive through it” there’s often a backfire-like sound under hood. My usual trips are very short, less than a mile, 3 or 4 times a day. I’ve run some fuel injector cleaner through it and changed the coolant, replaced rotor, distributor cap and wires, but that’s about it. Although I’m not a trained mechanic, based on symptoms, I think I may have ruled out coolant temp sensor and throttle position sensor. Any ideas before I submit to the mercy of the dealer? Thanks in advance!
  • tidestertidester Posts: 10,059
    You may also want to check out Grand Cherokee Shuts Off While Moving.

    tidester, host
    SUVs and Smart Shopper
  • daniemudaniemu Posts: 1
    I have a 1995 Jeep Grand Cherokee and yesterday the check engine light came on. I didn't notice any change in how the vehicle was running (the temperature and oil gauges were fine). I stopped at a shop to get it checked out, but wasn't able to get in. When I got back in my car, it didn't come on the rest of the way home. I wasn't sure if I should take it in, or if this was possibly a fluke.
  • jdchjdch Posts: 1
    When I start my 98 Cherokee, the check gauges light comes back on as there is about a 20sec delay before my oil pressure gauge begins to read any pressure. It used to begin reading immediately along with all the other gauges. This behaviour began after my last oil change. Once it begins reading I have normal pressures of 40-50 at speed and as low as 15-20 (warmed up) when idling. What would cause this delay and should I be concerned?
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