Adame24

I have recently purchased a 1998 5.9 ZJ with 154k. It is clean with no rust, however I have a constant noise when driving that makes it seem like bearings in it are bad. I'm looking for help in the NC area in diagnosing this problem. Can a fellow member help me out? (I am stationed at Fort Bragg/Fayetteville FYI). Thank you in advance for your time.


V/r,
Adam

dave1123

Welcome to CF!

I'm living just outside Fayetteville, New York, (LOL) but maybe I can get your thread started. I'm a Navy vet from the mid 60's and once owned a 97 ZJ.

First of all, what t/case do you have? Is it the Quadratrac AWD or the Selectrac with the 2WD option? Does the noise sound like a grinding or a whine and is it coming from the front or rear? Is it louder under power or when coasting? Take a sample of the rear diff fluid by sticking your finger thru the fill hole. What color is it and does it have a silver look like it has metal particles in it? Check the front diff the same way. Try pulling and pushing on the driveshaft yoke up and down violently to see if there is any looseness in the pinion bearings. (front and rear diffs). Look at the driveshaft universals for signs of wear and looseness at the t/case ends. Check the t/case fluid for color and quantity.

Next check all your wheel bearings for looseness. If you have access to a lift, put it in gear running up in the air and listen to it in each area to see if you can isolate where it's coming from.

That's a good start to diagnosing the problem. Let us know what you find.

Adame24

Thank you for the help, Dave.

I replaced the fluid in the differentials and the fluid was black in both. The amount that came out also seemed a bit low. I only took the cover off the front differential (the rear I sucked out), but the front had a hefty amount of metal shavings on the magnet.

As for the transfer case I also drained and filled it. The fluid level was black and also very low. It appears to have been leaking out of the rear seal as the undercarriage is covered in a film of oil.

I grabbed both drivehshafts to test for noises and the transfer case appeared to move a little bit (not sure if this is normal). As for the wheels I grabbed them when lifted and there was also a little play, but I do not know what is an acceptable amount.

I definitely know the metal in the front diff is not a good sign. Any thoughts?

A

dave1123

Yes...metal shavings in the diff are not a good sign. If you have a 2wd option in your t/case, you use the rear diff more under power than the front and it could be worse. I would have BOTH differentials checked by a good axle man to see what should be done. Usually heavy truck shops can handle this if there aren't 4x4 specialty shops in your area. You yourself can check the ring and pinion gears for spauling on the tooth faces. (little chips and cracks)

I checked my own by flushing them out with kerosene and inspecting the teeth, removing the driveshafts and tires, pressing back the brake pads and hand turning the pinions to feel if there was any "catching" in the bearings. I refilled both diffs with 75W-140 Synthetic gear lube that has friction modifier in it. I've got 183K on it with no gear whine.

Adame24

I will be taking it to a shop this weekend for inspection. I just fear that neglect by the previous owner is not going to be a good sign. It's possible that the gear oil was original