Clunk, clunk, clunk

[sportsguy]

OK, so this snow was the first real test of 4WD in the Comanche.

Drove home after the meeting on Saturday night in 4-HI with no drama - I love my Jeep! ;D

Went out yesterday afternoon - needed 4-Lo to get onto the main roads, 2WD after that - again, no drama.

One the way home, running uphill, through snow in 4-Lo, I started to hear a clunk, clunk, clunk noise - sounded like it was under the cab, but who knows.

Turning the steering wheel had no effect on the noise.

Since the clunking varied speed with the road/wheel speed, I'm thinking driveline, not drivetrain - axles/driveshafts, not engine/tranny.

Sounds not there in reverse, though (maybe I just didn't go far/fast enough to hear it, though).

So, driving forward, in 4-Lo, clunk, clunk, clunk.

I have had the t-case and diff fluids changes, so I know they're fresh and topped up (APJ's).

I'm guessing I need new u-joints for my front driveshaft.

Never thought to try it in 4-Hi to see if the noise was there - of course, I needed 4-Lo to keep moving, so, well, you know...

Anyone else have any thoughts? Any weird problems with 231's that occur only in 4-LO?

89 Comanche, AW4, 231 4.0

[blacksheepxj]

Check the front U-joints in the Axle shafts. Also with the Vacuum disconnect in the front when you are in 2wd you should not have anything turning in the front. I think. Also could be your slip joint on the front Drive shaft.

[Sandboxcowboy]

Duane..... just turn up the radio........Normal Jeep noises!!
That is until u can "feel" the problem below u!!!! ;D

Justin

[jjcan]

blacksheepxj said:

Check the front U-joints in the Axle shafts. Also with the Vacuum disconnect in the front when you are in 2wd you should not have anything turning in the front. I think. Also could be your slip joint on the front Drive shaft.

Actually even with the axle disconnect doing its thing the axle shafts still turn. however there will be no load on them.
So examine ALL the u joints remembering that you need to block the wheels and be sure the transmission is in neutral (NOT park) so the drive line is unloaded allowing loose U Joints to show up.
John

[sportsguy]

Thanks guys.

Took a run by APJ's yesterday evening and the first stop will be to replace the driveshaft u-joints.

[Grizzly]

On my other front DS I had on, my slip was very loose and it made a clunking noise when in 4-Lo. Check that when DS is off.

[sportsguy]

Good call Dmitri - I'll have that checked, too.

[littlemulticoloredwagoneer]

also have your tranny and motor mounts checked!!

[sportsguy]

littleredwagoneer said:

also have your tranny and motor mounts checked!!

I think they checked these shortly after I bought the truck, but I'll get them on it again, just to be certain. Thanks.

[davecar]

I had the same clunking and APJ fixed it with a new vaccuum pump for 4 WD. The clunking still happens sometimes in 4hi.

[sportsguy]

Thanks Dave - looks like I gots me a laundry list of items to watch for - much better than guessing!