While my XJ is turning over, running at around 3k on the tach, accelerating after a dead stop, and somtimes pulling hard up hills when the tach hits around 3k a rapid clunking noise almost like my front driveshaft is coming loose. This clunking used to be only during startup and leavin stop signs but now its gotten worse. Im not sure how to check the motor mounts. I checked the driveshaft in the front and the only play is it rotates about an inch clockwise and counter-clockwise, so i dont think thats the issue. If anyone an help me out with this problem id appreciate it, id like to fix it before i install my lift

 

Climb under the Jeep and look at the exhaust. You'll see that it routes right over top of the transmission cross member. There's a hanger there. How close is the exhaust pipe to the cross member?

When the exhaust is cool get under there and try to move it around and see if you can get it to make contact with anything.

 

On a related note, I have seen on some lifted Jeeps have that same problem. It is the front oxygen sensor hitting the front drive shaft.

 

just a thought but check your axle((wheel)) joints you might have play in those u joints

 

Thanks lowrange2, i think that might be the problem or part of it. The exhaust pipe is pretty close to the cross member and if you pull down it hits that crossmember so im gonna get some hangers when i get a chance. The o2 sensor up front clears and ill check the front wheel joints when i get home from school tomorrow, not enough time to lift it and check it today.

 

I put a couple hangers on the exhaust and took the car out and the noise is still there, i was merging onto the highway and it almost sounded like my driveshaft or somthing was about to come lose and go. The clunking/thumping noise was pretty bad. Im going to check all of my Transmission mounts, U-Joints, Ball Joints, and Motor Mounts to see if i can solve the problem. One sound worried me though, when i have the car in park and take it up to between 3k and 4k on the tack there is a slight clunking noise similiar to the one i feel/hear inside the car coming from somwhere in the rear of the engine or possibly behind it, Could that possibly be the transmission mounts causing the issue? I hope its not a stuck lifter, I listened to videos on youtube of what those sound like and they make a loud ticking noise, which mine is not doing.

 

I am having the same problem. Does your steering wheel shake at all around 55 mph?

I have replaced both hubs and still have the clunking noise and vibration.

 

Def check ball joints, bearings and u joints. As for that noise itself, you mentioned there's a lot of play in the shaft? A good amount of play is NONE. That goes for both the front and rear shaft. The rear you can replace the u joint, the front you can try greasing the shaft (should have grease fitting). If you want, pull the shaft off- 4x 8mm bolts on each yoke. Your 98 has fixed yokes so no worries. Could it be the flex plate? It would kinda make your XJ sound like a big rig..

 

Yah I have play in the front driveshaft, i can move it toward the front and back of the car about a half inch maybe less each way, but not play up and down or side to side. So your sayin grease that fitting and it might fix it? And how can you tell if the flexplate is bad?

 

Not often but it has happened at 55, but more often at around 75mph

 

I found out that the inner flange in the double cardan joint is bad. But that has caused the bearings to go bad in the front diff.