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Help with clunking noise

3K views 14 replies 6 participants last post by  rideordie1113 
#1 ·
When I pull out in 2nd and I don't work the DD clutch quite right, the truck likes to buck a little bit.

Lately, however, I have started to notice if it bucks that there is a pretty bad sounding clunk that happens at the same time. It sounds like its right below the cab. I'm not really sure where to even look...Any suggestions?

Secondly, there is another clunking noise (which doesn't sound nearly as bad) in the front end when you hit a bump. I'm fairly sure most of the front end has been replaced by now. I haven't gotten a chance to look at it yet but I was thinking maybe control arm bushings?
 
#5 ·
u joints seem to be ok.. Not much play in any of them.. There is what I would consider a decent amount of pay in the transfer case when playing with the front drive shaft but I don't see why that would make noise unless I was in 4wd..

There is also a very slight clunk Sometimes when you hit a bump. I didn't think they were the same issue but it's possible I suppose. The one when pulling out sounds awful though. The one when you hit a bump sounds pretty mild.
 
#7 ·
Not much play can be enough play to get a u-joint to clunk.
 
#9 ·
Look at your exhaust system. Is it loose?
 
#12 ·
I checked that already..That was one of my first thoughts, but I can't get it to budge much at all so I don't think that's it.

Sway bar end links
Sway bar bushings and links are about 500 miles old.

make sure to confirm visually that the movement in the rear diff is actually in the rear diff and not in the rear u joint...

the front driveline will spin freely while 4wd is not engaged; while I do not believe this is the source of your noise, I would suggest placing the TC in 4H and seeing how much play is in the front driveshaft at the TC side of the driveline. Then disengage the TC and find a way to hold the differential yoke and check for play in the u joint at the front diff (if someone has a more specific way to check this, please advise)

when mine was clunking, I originally thought it was the rear diff going out...
replacing the u joints was a welcome surprise compared to rebuilding the rear diff...

there should be ZERO play or slop in the u joint unions...

hope this is helpful...
~V
I had the TC in 4H and then in 2H and checked it both ways..I'm fairly certain the play is from the transfer case slop itself, not the u joints. I couldn't get any of the u joints to move at all.

I was thinking today -- is it possible that the transmission mount could be "OK" but have enough play in it for the transmission shift tower to be bouncing into the sides of the floor where it protrudes through it?

Wouldn't quite explain the slight noise when hitting a bump sometimes, and I don't think there's really a way to prove that it is what is making noise, but just a thought.
 
#13 ·
I didn't mean to complicate the issue with the front driveline...
In my experience, I had the occasional loud clunk from a bad u joint where the driveline and rear diff connect. Shortly after that was repaired, I sheared the front u joint where the TC connects to the front driveline and took out the tailpiece housing between the nv4500 and the TC: I was lucky I didn't take out the TC. Upon inspection it was obvious that the u joint failed d/t excessive wear.

Anyways, since it sounds like you have eliminated the front suspension components, the exhaust and the driveline components what's next...

I personally would try to duplicate the noise conditions with someone outside observing in order to isolate the component location and proceed from there.

Anything is possible with respect to the mount on the tailpiece between the NV and TC; however, in 300k + miles I have not experienced this with my rig.

I could feel the rear u joint clunk under my feet in the floor of the truck, before knowing that it was in fact the rear u joint; on closer observation, we were able to determine that the noise originated from the rear end.

Have you checked the fluid level in the TC?
~V
 
#15 ·
You said you think most of the front has been replaced, but i"d check the ball joints any way. My has started making noise that I fill next to my feet and I found the left ball joints are loose.
I did not check the fluid level in the TC. In August it was all torn apart due to my transmission getting rebuilt. When it was apart I changed the fluids in the TC and transmission, so they should both be good -- but I will check on that to be sure.

It's easy to get it to replicate the noise, but I don't know how you would get it to do it without driving it.

I jacked up the front tires and checked for play up/down and side/side. The right side was perfect. The left side had a VERY small amount of play (IMO, anyways) side-to-side. I don't think that it was enough play to warrant anything needing replaced, let alone making a noise like that.

The exhaust, when pushing and pulling on it by hand, seems pretty stable.

I tried prying on control arm bushings with a pry bar. The upper arms are pretty hard to get to and I'm not sure how to check them real thoroughly, but the bottom ones seem fine.

I am tending to aim towards a body/cab mount that is worn out, or upper control arm bushings. I don't think a driveline (u-joints, for example) issue would clunk when you hit a bump - unless, of course, they are two different issues..but I don't think that's the case.

I painted the underside of the truck with chassis saver over the summer, so it's hard to look for cracked bushings/mounts etc. since they are mostly covered..
 
#14 ·
You said you think most of the front has been replaced, but i"d check the ball joints any way. My has started making noise that I fill next to my feet and I found the left ball joints are loose.
 
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