Help Diagnose my clicking/thumping sound.

It started non-stop on friday. It sounds like my tire rubbing on something but I know it's not. It gets louder and faster when when i accellerate. There's no ticking when I just rev the engine. If I'm accellerating and shift into nuetral the ticking goes away, even at the same speed. If I apply the breaks and give it gas the ticking gets louder, but doesn't speed up unless the vehicle speeds up. I removed the front drive shaft to see if that was it, but it didn't help. I jacked all the tires up and spun them but no ticking. I ran the jeep with the rear tires off the ground and I don't think I heard ticking even when applying the breaks, but maybe. The drivers side shaft moves in and out maybe 1 or 2mm, the passenger side wiggles, but doesn't really move.

It first started a month or so ago, and only occasionally when I would accererate from a stop at a left turn. I just thought my exhaust was rubbing the tire since one of the hangars is missing. Then friday just before I got home I suddenly here this soft, deep rumble. I thought the exhaust had finally cracked sicnce I was missing a hangar, but once I came to the stop and heard the ticking, I knew it was something else.

That about all I got.

Thanks for the help.

Have U looked closely at the U joints on your drive shafts and front axle? Thats what I'd check first.

What would I be looking for? They don't appear to have any problems.

Check your engine mounts. if they're cracked or broken, the engine may move forwards just enough during braking to cause the clutch fan blades to scrape the shroud (or worse, the radiator!).

Ok. Here's my latest theory. look at these pictures (they are a little redundant):








Notice anything? Me neither, except the pinion appears to be pointed slightly above the driveshaft (oops). Over 9 months of driving (~25K miles) could this have ruined the u-joint? Or worse the r&p? Changing the U-joint tonight just incase.

You sure it's not a cracked header pipe???

Why would that have anything to do with how fast the drivetrain is spinning (NOT the engine RPMs). It is definately a mechanical sound, not an exhaust leak sound.

Talked to the local old drivetrain guy when I was going to buy the u-joints. He said it seems like a spider or pinion gear tooth. So I'm gooing to pull the cover tonight. I'll take some more pics

So I pulled the diff cover. I checked and rechecked the pinion, ring, and spider gear teeth. No obvious breaks or even nicks. They look quite worn but I don't konw if it is normal wear for 120K miles. The oil was very dark and brown. Couldn't really see through it at all in a jar, even with a 500 watt lamp behind it. Only found one small piece of metal and it looked like it could be from the bolt threads.

I guess I'll actually try the rear drive-shaft U-joint tomorrow. Any other suggestions? I gotta get this thing running again so I can drive it to work.

I would have a good look at your pass side rear wheel bearing. its the rumble that worries me. what is the frequency? speed of the driveshaft or speed of the wheels? how does it change of deceleration.
I am just looking for a little more detail.
a u-joint is usually accompanied by a vibration.

It seemed like the speed of the driveshaft - faster than the wheels were turning. The rumble - which just sonds a little like a crappy after market exhaust - is just the ticking/nocking/thumping (whatever the hell it actually is) reeeaallly fast. Braking doesn't seem to effect it other than when I let off the gas the sound gets softer. At slow speed the sound nearly goes away without the accellerator. Barely hear it at all in reverse, though I didn't try accelerating very hard in reverse.

Thanks

EDIT: For the bearing do I have to pull the axle?

yes you have to pull the axle for the bearings. but if the speed seems to match the d-shaft then I would then consider the pinion bearings.
go to www.ring-pinion.com. click on tech articles and there should be one or two "paper" on diagnosing noises.
if you have any other Q?s then I will get back to you on them tomorrow. I'm tired... bedtime.:speepin:

Do you have a SYE installed? What brand?
Look closer into CV part of d-shaft...Center ball and pin could get worn out and start making that type of noise....
Other that that i would look into T-case. Is it 231 or 242?
I hade clicking noise in frnt d-shaft CV unit....took it apart, replcd u-joins, and it was all good. Then I got Wood's shaft with greas fittings everywhere....Keep it lubed always :spin1:
U can leave frnt d-shaft and remove rear one and t-drive it to see if the sound is still there...if not, then it is for sure rear d-shaft...
Good luck!

Thanks Raw I'll check it out.

Front shaft is off. Still making the sound. I did the hack n tap with RE shaft in March or April. I haven't lubed the u-joints since install since I keep getting crappy adapters to fit the small space. 231.

Once I get the diff back together, I think I'll put the front shaft back on, remove the rear and see if the sound is gone. If so then I prablably have narrowed it down to the rear shaft, rear axle, or the out put part of the TC (?). Thanks again.

Incase someone is having similar problems here's an update:

The CV joint was "toast" as the driveline guy put it. My pinion was pointing a few degrees higher than the shaft which he said puts a tremendous amount of bind on the joints. I think the angle was close when I first put the lift on, but after adding bumpers, winche, skid plates etc, the inch or so of lift I lost reduced the driveline angle, making the pinion angle worse. Thats my theory anyways.

One indicator it was the CV was when it was all bolted up, I could ever so slightly wiggle the CV end of the shaft if I pushed just right.

Later.