mad.scientist

Gents (and ladies),
I have a 1991 4.0L 6-Cylinder Manual trans cherokee.
I've been dealing with a squeaky jeep for some time now(pretty much all fall an winter), and I am out of ideas.
Here are the symptoms:
-smooth idle, no squeaking on start up, or when idling
-when driving in 2WD, usually once I reach second gear, I start to hear a pulsing squeaking that appears to be coming from the front of the engine compartment. The squeaks seem to pulse every second or so (~1Hz).
-If I put the jeep in 4WD, there is no squeaking.

What I have done so far:
-New Battery
-New Alternator
-New belt
-New idler pulley and AC bypass idler pulley bearing
-PS pump pulley bearings seem ok, as does the water pump bearings. The pulleys turn by hand with the expected resistance.
-New breaks last summer(pads and rotors)
-I replaced the internal clutch slave cylinder last winter(good gravy was that a pain...) and when I did that, I greased the hell out of the U-joints in both front and rear drive shafts. I know that the front one can squeak, but I'm pretty sure it's not the culprit...
-I've played around with the tightness of the belt on two different occasions, I originally had it about the tightness that the Haynes manual says to have it, but for curiosity sake, I tightened it more when the squeaking didn't stop.

I've read on here that the distributor can squeak.... Could the distributor cause a pulsing squeak? And if so, why would it go away when in 4WD?

As I said, I'm all out of ideas. Any suggestions would be greatly appreciated.
Thanks,
-Pete

summit700

I believe I have the exact year Cherokee and exact problem. I have been trying to find it for months too can't find it. I to am stumped

mad.scientist

Thanks for the reply summit700.

I've decided to take a bit of a video with the sound in it. See the link below:

I think the squeak sounds like the belt... but it doesn't seem to change with RPM. If the rate of squeaking changes at all, I'd say it changes with speed of the vehicle.

Any thoughts?
Thanks in advance.

mad.scientist

Upon closer inspection, the squeak could be coming from the transmission or transfer case.

Any thoughts on what that might be?

summit700

thats were ive narrowed my search down to as well. ive got complete front end rebuild, removed brakes, changed pads, greased and lubed every thing. was gonna remove front driveshaft next to c if that makes it stop. i really pushing towards in the tranny though . as to why i dont no. next step is to bring it to just jeeps a local jeep specialist

rich86

I had the same problem was my front driveshaft try taking it out if the noise goes away its the shaft check the ujoints if they are good then it may be the in the joint by the transfer case in that rear joint between the 2 u joints there is a ball in socket joint in there in mine that went bad and was causing my squeak i put in a good used drive shaft and the noise went away give that a try and see what happens

mad.scientist

Thanks for the reply rich86!
I'll try removing the front drive shaft this weekend and see what happens.

rich86

Your welcome that's what worked for me on my 89 cherokee but yours could have a different problem but give it a try and see if it works for u its always worth a try since its very easy to remove the front shaft should only take about 10- 15 mins if ya have never done it before but its really simple to do

mad.scientist

So, I removed the front drive shaft today and the squeak is gone. It appears that the rear u-joint in the front drive shaft was the source of the pulsing squeak. Thanks Summit700 and rich86 for the advice.
Does anyone know if it is a bad idea to drive around without the front drive shaft for a while? I have to move soon, and the trip is about a 7 hour drive. I'll be driving the jeep that distance, and as of right now, am planning on making the trip with the front drive shaft removed... Anyone see a problem with this?

rich86

Your welcome u can drive just fine with out the front drive shaft out ya just will not have 4x4 any more lol but that is the only down side of having it removed as far as I know for the research I have done
Rich

rex21

It is most likely the ball inside the double cardan joint that is squeaking. Won't hurt a thing to run with no drive shaft.