2011 Denali..So about this clunk I got...

[fngh]

Hi all! My name is mike and I just joined your forum. First time GM product owner. Recently I bought a 2011 Denali awd w the 6.2( also being a noob, should I say that stuff or do you guys already know the specs given the year and the model?Trying to learn, so will not take offense, lol nu guy shit) anyhoo, so got a good deal, but cuz lil things need attention. First is the clunk. There is a clunk coming from the rear, shifting from P to anything, as well as from dead stop to accel at lights and decel stopping at lights. Shit, maybe I should just run em. LOL juuuuust kidding. So as a f**kin new guy( like my name title thing FNG) anybody know what to do? I got other issues that I will ask y'all but this one is my first target as the others are mostly cosmetic and tech stuff that do not affect the driving experience. real quick, its an 11, 6.2, 103xxx mi, awd, ummmmm flex fuel( if that matters, I use 89 or 91 never less, or should I be? says premium but not always avail, rarely tbh but trying to be completely transparent). I heard this was common but I came here cuz believe it or not, Youtube mechanics are not always the best source for info. I know! Im just as shocked! LOL, anyways, seriously, thanks for your time and any advice is much appreciated. Hope to hear from u soon. Sincerely, Mike(aka FNGH) Be well

 

[drakon543]

first up depending on the specifics of a question vehicle information can be a big help. gm has so many variations to thier vehicles that either follow exact model( z71, hd, you get the idea). the other one would be your rpo codes in the glove box. they can go as far as telling someone the specific gear ratio you have. either way welcome to the forum. closest ive come to this particular problem was my neighbors hd work van. he started to notice this and he went back to the dealership where he bought it numerous times just being told it was normal. i convinced him to go to another gm dealership and they found a pretty serious problem. the bolts for the differential were never torqued down. less serious would be your u joints could need to be replaced in your drive shaft. block the tires so the truck doesn't move and shift to neutral. slide under the truck and check for play in the joints and where it goes into the rear end and transfer case.

 

[PatDTN]

If the u-joints prove to be okay you'll want to chock the front wheels and raise the rear wheels off the ground. USE JACK STANDS. With the truck in park and parking brake released try to turn the rear wheels back and forth (forward and backward) to see how much play there is in your rear gears. I have a Tahoe now because the diff on my previous Sierra was shot and would rotate quite a ways on this test.

Welcome aboard, this list has been a Godsend for me.

 

[Big Mama]

Welcome from Virginia. There’s a recent post about this clunk. I have the same rig but an 07. It doesn’t do it when decelerating though. Dealer told me the same thing, it was operating as designed but there’s no way that’s right. One thing also to check is the diff fluid. If someone changed it and didn’t add the non-slip additive the clunk is worse but also check motor mounts when checking U-joints and axle play.
https://www.tahoeyukonforum.com/thr...t-slip-yoke-solved.119545/page-3#post-1503715

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics, please.

You've already been given some sage advice on where to start looking for the source of the clunk. @Big Mama has already referenced a thread (mine) where one solution to the clunk, although it was not the most common source of the clunk, was identified and solved.

 

[Doubeleive]

welcome a clunk could be many things, broken motor mounts, slip yoke, u-joints, sway bar end links, transmission mount, front differential mount, brake calipers, and I might be missing others.
I would recommend at the very least getting a flashlight and get under the truck and just look at everything real good for starters, others have already given you some things to look for and then let us know what you find. If you see any significant oil leaking from places other than the engine area usually that is a pointer something is wrong.

 

[thompsoj22]

Hey welcome to the forum and congrats on the new denali,are you mechanically inclined and do you intend to do most or all of your repairs? This forum and a tech2 can enable "allmost" anyone to purchase exactly as you did, diagnose and repair it so youll be all smiles in no time at all! IMO, just crawl under the vehicle on flat ground and find the slop,loose,damaged,worn part and down the road youll go. ill guess rear driveshaft u joint?

 

[wjburken]

If the u-joints prove to be okay you'll want to chock the front wheels and raise the rear wheels off the ground. USE JACK STANDS. With the truck in park and parking brake released try to turn the rear wheels back and forth (forward and backward) to see how much play there is in your rear gears. I have a Tahoe now because the diff on my previous Sierra was shot and would rotate quite a ways on this test.

Welcome aboard, this list has been a Godsend for me.

Keep in mind his vehicle is AWD so he won’t spin the rears too far with the front wheels on the ground.

 

[PatDTN]

AWD... won't really matter. He doesn't need to spin them, just rock them back and forth to see how much play there is.