ducter

My son just picked up a WJ, front driveshaft was out because guy said it needed u-joints, replaced the front one and best we could inspected the rear boot for and rips or tears but looked good and feels smooth. Basically getting clunking and grinding sounds when the front driveshaft is installed, it's a np247 so full time 4wd, remove driveshaft and the noise goes away. Inspected CV axle and found drivers side was torn so replaced it but no change. Here's a video I made the other day so you can hear the sounds. I am not sure how to embed. Appreciate any help.

dave1123

I would check out the front differential internally. You may have bad pinion bearings.

ducter

Wouldn't that make the sound regardless, with or without front driveshaft? Or do you think adding load to it changes it?

Thank you for the reply.

dave1123

Yes, my thought was it needs power to it to load the pinion to make noise. Otherwise just the axles are driving it. This is just my opinion and it needs to be checked out to see if I'm right.

ducter

He picked up a used transfer case because that's what we had figured it to be, warms up a little outside and we'll have to figure it out. Because we have it and it looks to be a pretty straight forward job I hope it's transfer case... Plus the whole point that I've never worked on diffs.

Cherokee_Mike

Check the CV joints on the ends of the front axle - to me it sounds like a worn CV joint - a lot easier to change than a transfer case.

ducter

I did replace the drivers side CV axle as it was in need, the passenger side looks newer and no signs of failure. The front driveshaft on transfer case side uses the CV style joint which looks good and operates smoothly by hand, the front side uses traditional u joints which I did replace. Thanks for the reply.

dave1123

Differentials are the most important and least understood part of ANY vehicle. It takes surgical precision and attention to detail to do them right. Well....okay, doing automatic transmissions is about the same.

If you need help with the front diff, you can check with a heavy truck repair shop. Some shops don't want to do jeeps or any small 4x4s, but some would love to do something small! At least they can tell you where to take it.

OR, you can put in a good used unit yourself.

caged

my worry is the viscous coupler in the transfer case. you really shouldn't be driving it without the front drive shaft installed as it needs it to safely keep the vehicle in park without rolling. this is of course if it's the all wheel drive transfer case. if it's a 2wd option vehicle, then disregard my post.

ducter

Yes, it's full time 4wd. It's my son's so it's not here now but you're saying it can roll when in park without the front driveshaft?

dave1123

Be aware the 02 has an NP247 with an improved gerotor coupling, not the viscous coupling that the NP249 has. Some WJs even have the NP147 which doesn't even have a T/C shifter!