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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
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!
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
" 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
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
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.
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??
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?
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.
SUVs and Smart Shopper
Mine does not die completely like the Grand Cherokee thread recommended by the host. Will keep forum posted if I succeeed.
fan could be fan clutch bad
1. emissions system not functioniong properly
2. fault in the fuel or electrical systems
3. faulty secondary ignition system (cracked sparkplug insulator or faulty plug wires)
4. vacuum leak at the throttle body, intake manifold or vacuum hoses.
5. valves sticking.
6. crossed plug wires- check the firing order.
7. valve timing incorrect.
trans has small cooler in side rad un pinch line for sure
Does this sound right to anyone?
Which is strange because a co-worker just had his 2002 cherokee 4.0L have the issue fixed. He went to a dealer. They replaced the sending unit. It was good for a couple of days... then back again. The dealer then replaced the pump at the tune of $450.00+. His issue has not returned in 2 weeks. He also never experienced the engine running rough when the issue occurred.
My wife's vehicle on the other hand was really struggling to keep idling. So, not having alot of cash, I decided to tackle the oil pump.... it is Michigan... 30 degrees and snowing in April.. NICE! I have been under the vehicle so far for about 8 hours across 3 nights. If I had a lift it probably would have taken me maybe 2 hours to get to this point. I am ready to put the new pump in.
That being said, if it gets to the pump replacement stage with you, I would suggest paying the extra $300 to have it done for you.
I will update this when the pump is in to say if it fixed it or not.
At any rate.... We never had the issue until the wife took the Jeep to a Valvoline quick change. The clown over filled the engine. I am guessing two quarts. This allows the oil to be aerated by the crank. Also, to be noted we had used a semi synthetic the oil change before. So, this oil change took us from semi synthetic back to plain oil.... maybe this could pay its part in root causing this issue...
more details to follow....
It never stalls, and always starts.
When it starts bucking, it slows down to around 40 mph, not fun when you are on interstate. Giving it more gas results in more bucking. It is definitely temperature related, during cold weather it takes longer to manifest.
I have checked the coolant & manifold temperature sensors, MAP sensor, camshaft position sensor, and fuel pressure. I have replaced the spark plugs, rotor, wires, and fuel filter.
I only get this problem for 1 minute, then it's gone.
The onset of the problem is gradual (15 seconds), and it clears up over a 15 second period as well.
i just fill it with grease befor i put them on
While driving it home the temp gauge showed 240 degs.
I checked it out and found that the fan relay is bad:
AC engages, fan doesn't go on.
Temp exceeds 210 deg., fan doesn't go on.
Switched the 40 amp fuse in the PCM, fan doesn’t go on.
Hot wired, fan goes on.
Is the fan relay on a 2000 GCL 4.0L the same and in the same place as your 2003?
If not do you know where it is located?