Diagnosing driveline sound, I'm stumped.

[brianhoberg]

Well, two weeks ago I thought I had a hub on the drivers side rear going out. My DII is pretty much stock driveline components minus the rebuilt front driveshaft withgreasable UJ's I replaced in it about 8k ago. Been keeping it all nice and greased, no issues.

The symptom is, when at a dead stop, if I punch the gas you will hear a grumbling sound (similar to driving at a high speed over the small grooves on the side of the road) for the first gear or two, then it goes away.You can feel a slight vibration from the drivers back, but nothing rattling or clunking or grinding, just the above mentioned sound. I thought it was a hub going out at first, but to be safe, I have been eliminating anything obvious and checking what I can.

This past weekend, I changed the motor oil, diff fluids, transfer case oil, and transmission fluids. All came out clear, the magnets did not have anything alarming such as excessive metal dust or any large metal chunks in it. Diff fluids were still clear and nice golden color, not dark brown. Transmission fluid was still red, very similar to brand new. No leaks from any of the components.

Greased the front driveshaft all up and the rear driveshaft's front UJ really well.

Called up a couple of rover mechanics who suggested I jack up the rear driver tire and see if I can shake it in and out at the 12, 3, 6, and 9 o'clock positions to indicate if the hub was loose. Nothing loose all very tight. Not sure if I should go as far as to take the wheel off and try to pull it the same way.

My question is this: Truck has almost 95k on it with the stock parts, minus the replaced front DS. Never had an issue with it before, all fluids clear and clean. Clear diff fluid indicates nothing abnormal with the differential. Hub isn't loose. I'm stumped.

If a bearing was going out, would it be indicative of checking the hub being loose? I DO have a broken motor mount on the drivers side that I am replacing this weekend. But can a broken motor mount resonate all the way through the driveline to the drivers rear wheel?

Any suggestions on what to check next are appreciated.

 

[tex599]

I just went trhough this with both my DI and DII. On the DI it was the rotoflex, which you don't have on the 04 On the DII, it turned out to be a rear u-joint, one single trunion (I think that is what it is called) had gone bad, that one cap was dry and rusty, with the bearings basically crumbled. Grease path must have been clogged. Did not realize it was bad until I removed the drive shaft and pulled the joint. Best thing to do, is remove each driveshaft, lock the CDL if you can and test drive until the noise is gone.

Mine made the same grumbling noise as driving over the grooves on the side of the highway when letting off the accelerator.

 

[eliaschristeas]

i kinda sorta have that highway grooviness going on too. but very faint (92 rrc btw). Sometimes its there, sometimes its not. However, from a stop and hitting the gas, it sounds like someone is hitting the frame with a hammar. sometimes soft, sometimes moderately. sometimes not at all. although both my d/s's were tight when i went a'hanging on them, i suspect a u-joint or pinion. Its also possible that its worn tie rods. its getting a little worse every week so in no time, i should know what it is - or at least blow up on the highway!

 

[Roving Beetle]

I would also bet it's a rear most u-joint. Or possibly the rear diff input bearing, but more likely the joint.

Trouble is *normally* the joints will vibrate when coasting not so much under load - if you have a broken motor mount the motor could well be moving enough to allow the exhaust to be hitting something. Rear end squatting a little from acceleration and the motor tilting could equal the exhaust rubbing on any number of things.

Look at the exhaust really carefully for any clean scuffed areas, wiggle it around and see if it's close to anything.

????

Doug

 

[singingcamel]

Change the motor mount and go from there. I had a grumbling sound on my D1 At idle the it was fine ,at 55 -60 mph it would grumble, changed it out and noise gone.. wish you well, the bolts on the motor monts suck, especially the drivers side, you will have to loosen both sides to change it..

 

[KyleT]

check the rear t-case output flange nut. I have seen it come loose a few times and it will vibrate and make weird noises. including on my D2. I did not notice what it was until my handbrake didn't work randomly one day. It was causing a vibration and noise.

When you get the motor mounts, search for the cheaper one on here, mine were reboxed d2 ones (machined aluminum not casted like the pics in the thread) and were $21 each.

 

[brianhoberg]

ok, will try the motor mount, then see what I have. I figure the rear driveshaft is defective with the rotoflex anyways.

 

[brianhoberg]

bump for other ideas

 

[eliaschristeas]

MY CLUNK SOLVED: all that talk of mounts got me wondering... especially since i felt the clunk through the frame under my left foot.

i checked out the t-case mount and noticed that a bracket bolt had somehow worked itself loose - 1 of the 3 that go through the frame. Here's what was banging: The e-brake light solenoid which is held in place by that very same bolt.

replaced bolt - no more clunk!!!

 

[kennith]

That's a bugger to figure out. It's happened to me maybe 6 times since I've owned the DII. Usually, when leaving a dead stop after hours of cruising.

I'll hit the throttle, then I get almost the precise feeling of driving over those rumble strips on the side of the road. It may even be slow to start moving when this occurs. It's hard to remember.

I must have asked 100 people about it if I've asked even 1. I still don't know what the hell it is. It happens, and then it doesn't happen again for a year or so.

I figured it was something in the torque converter or transmission. As if it was having trouble deciding whether or not to be locked upon acceleration after cruising that long. If it was the transmission, I chalked it up as a little slipping.

I've never pegged it. I could almost swear it felt like the truck was slipping a bit, but I can't remember for sure.

If you get a concrete answer for that issue, I'll send you money for a case of beer.

I don't think it's anything too harmful, as I've lived with it for a long time now. It does feel just like rumble strips, though.

Cheers,

Kennith

 

[mastercamper]

Any update on this? I have something close to this, just rebulit my front drive shaft and had it balanced, still has a slight vibe. But I'm hearing a noise and feeling something that seems to be coming from under the arm rest, doesn't happen all the time, kinda here and there topped off the TC and trans fluid is good, that leads me two two things TC or swivel ball in front shaft. This is one of two mystery noises I've had for almost 2 years nothing's broke yet, I'm just at a loss of what this is. How would I check the TC bearings? I know the front output has a little play, it will move a little but just barley when pushed on.

Its an 03 D2

Eric

 

[brianhoberg]

yeah, turned out that my drivers side motor mount was broke completely and the passenger side was broek on 3 corners. Looks like the vibration was coming (for me) from the broken motor mounts, down the dirveshafts and then to the back axle. I dont hear it anymore since changing out to just the factory motor mounts that I bought from Gem. I'd just recommend factory over spending a lot on the Qt motor mounts. Sure you never have to replace them, but they directly bolt the engine to the frame with no isolator. You hear a lot more noise from the engine than with the OEM ones.

 

[gmookher]

go with qt from justin when those break...the noise subsides after a few hundred miles, i no longer notice my qts, they are isolated, look closely at the 15/16 bolt hole...

its a bear to do in the feild, on your back, in the mud...do qt and set it and forget it...

 

[mastercamper]

yeah, turned out that my drivers side motor mount was broke completely and the passenger side was broek on 3 corners. Looks like the vibration was coming (for me) from the broken motor mounts, down the dirveshafts and then to the back axle. I dont hear it anymore since changing out to just the factory motor mounts that I bought from Gem. I'd just recommend factory over spending a lot on the Qt motor mounts. Sure you never have to replace them, but they directly bolt the engine to the frame with no isolator. You hear a lot more noise from the engine than with the OEM ones.

Did you noise come and go? or was it constant? I'll have a look at mine later.

 

[ml4x4]

I have the EXACT noise as originally posted. From dead stop, slight grinding type of noise on fast acceleration. I first inspected the engine mounts as I had a similar noise before and when I discovered a broken mount, fixed it, noise was gone.
This time, no broken engine mounts so I'll look for what happened to you and see what I come up with and report back. This is annoying as shit and I've searched all over the truck for the problem. Just before I read this, I was thinking maybe I had low transmission, transfer case, or diff fluid, etc.

Thanks for the post! I hope I find my issue.