2500 series front end clunk

[TrybalRage]

Hey everyone. I also posted this on the 2500 series facebook group, trying to find a solution or ideas.

My new-to-me 2010 Suburban has a front end clunk. Weirdly enough, it doesn't seem to happen at all when the vehicle is cold, but only after driving for a little while when things get warmed/loosened up.
I do not feel it in the steering wheel, only in the floor under my feet. Passengers can hear it as well. It happens while driving straight down the road, when there are dips - not really 'rough' parts, but stuff that makes the truck go up and down, if that makes any sense.

I can also feel it (once warmed up) when coming to a stop (clunk); and sometimes when getting on the gas (clunk). But not always. Almost like it's related to the weight shifting forward or back.
Popped off the drivers wheel and found the brake caliper was pretty loose (worn out bushings) so replaced it. In my experience clunking is often related to shocks so got new bilstein 4600's all the way around. Still clunking.

Grabbing the tire at 12 and 6 and rocking has no movement that I can tell. Rocking at 9 and 3 has some movement but no noise. So I'm going to start looking at the steering linkage next.

Some other things on my list of possibilities thanks to google:
-Intermediate steering shaft, but that seemed to be more of a problem on the previous gen models.
-Sway bar end links: They seem solid but who knows
-Ball Joints: Not feeling any rocking but might be worth replacing anyway.
-Torsion bar crossmember bushings

Anything else I should be looking at? Anyone experience a drivers-side random clunk?

Thanks in advance.

 

[Doubeleive]

lube the D bushings on the sway bar front & rear, while you have front wheels off the ground check the front sway bar end links again if the bushings are worn out go ahead replace the end links.
the rear is done with wheels on the ground
other things to check are motor mounts, open the hood so you can see thru the gap and watch the engine while you put it in gear and hold the brake and give it gas in forward and then reverse. it will move a little but shouldn't move much.
you could also check the front diff mounts if it is 4wd.
while you under there use a flashlight and just look everything over real good, controls arms, shock mounts, etc.
if a shock is leaking fluid that could be a source also
if you have air ride check the rear shock bladders, they should be firm.

 

[TrybalRage]

lube the D bushings on the sway bar front & rear, while you have front wheels off the ground check the front sway bar end links again if the bushings are worn out go ahead replace the end links.
the rear is done with wheels on the ground
other things to check are motor mounts, open the hood so you can see thru the gap and watch the engine while you put it in gear and hold the brake and give it gas in forward and then reverse. it will move a little but shouldn't move much.
you could also check the front diff mounts if it is 4wd.
while you under there use a flashlight and just look everything over real good, controls arms, shock mounts, etc.
if a shock is leaking fluid that could be a source also
if you have air ride check the rear shock bladders, they should be firm.

Thanks. 4WD, no Air ride. Just put new Bilsteins on last night.

 

[Doubeleive]

Thanks. 4WD, no Air ride. Just put new Bilsteins on last night.

try lubing up the sway bars, take the D bushings off and get some grease inside them and put them back on, usually about this time of year when the weather changes it makes mine make a little noise due to moisture. doing that may help with the clunk noise. There is a spray that can be used as well but it won't get the grease where it needs to go, I use that around the other bushings like on the control arms that are not easily removed.
you may want to check your body mounts as well.

 

[Keanen55]

Motor mount possibly bad? They tend to go on the driver's side first!

 

[Joseph Garcia]

Differential mounts would be my guess, but @Doubeleive gave you an excellent list of possible sources for your clunk, and I suggest that you check out those possible sources, one by one.

 

[TrybalRage]

OK, so a little diagnostic update.

Got the front end up and looked around with a flashlight, sway bar end links seem good, used a pry bar under the drivers tire to test the ball joints - no wiggle no noise. Steering components seem ok (I didn't realize these trucks don't have a locking steering column, so weird). A lot of the stuff looks old but not worn out, and wiggling/prying/yanking on stuff does not show any unusual movement.

So today I went on a short drive until the clunking started (remember, doesn't happen when cold) and then came home and had my wife drive forward and backward gas-brake, gas-brake, gas-brake because we can sometimes get it to clunk like that once it's started.

I do not hear anything at all near the front end or suspension. In fact, outside the truck I can barely hear it at all. It seems to be coming from somewhere near the middle-ish of the vehicle but my wife seems to think she can hear it around the steering. I still feel it in the floor.

Jumped into the engine bay and yanked on the steering shaft, maybe a little bit of looseness but she didn't hear the same sound inside.

Got it back up on stands and the trans mount seems Ok. Again looking around with a flashlight and just yanking/prying shows no movement of anything I can see.

So I get online and see something about 2500 silverados and sierras having a driveshaft yoke clunk... some grease seems to be a short-term fix so I'm going to try that, it will cost me nothing to try.

Also going to check any mounting bolts for the front diff. I'm not familiar with 4wd systems so I'm just poking around at the moment.

 

[Keanen55]

Open the hood, have your wife step on and hold the brake petal and tap the gas and watch the engine for excessive play. I bet you that you driver's side motor mount is bad. I had the same thing happen to me last year. I changed everything out in the suspension and it was still making that noise. Turned out to be the motor mount!

 

[TrybalRage]

Well, yesterday I didn't find anything that stood out to me as being loose or off. But while I had it in the air, I went through and greased all the front end parts (why not) and put a very light coat of grease on the driveshaft spline (costs nothing to try) and while I was in the vicinity changed the trans mount (what the heck, it was only $16).

Wife had gone out for the day while I was tinkering and I had totally forgot to do the motor mount test. I did take note that it looks like that's not going to be easy to get to, so yay for that if it is bad.

I'm happy to report that the clunking is diminished quite a bit. So one of those things I did seems to have helped but not eliminated completely. I definitely need to get a better look at the mount, makes me wonder if the new trans mount is sort of helping hold the whole thing in place for the time being... if so a bad motor mount will probably ruin this new trans mount in short order.

I've also decided that I'm just going to start systematically replacing all the wear items in the front end. As I was looking around, like I said nothing jumped out at me as being 'bad' but at 136k I'm sure it wouldn't hurt to freshen it all up.

 

[Joseph Garcia]

Motor mounts and/or front differential mounts. My bet is on the front differential mounts.