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Tom
Tom, ASE Certified Technician
Category: GMC
Satisfied Customers: 25927
Experience:  ASE Certified Master Technician
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I have a 2003 GMC Yukon Denali AWD. Every time I accelerate

Customer Question

I have a 2003 GMC Yukon Denali AWD. Every time I accelerate I hear a clunking noise. I lay off the gas then accelerate again then a clunk or thud. I've had a ton of work done. New transfer case front differential universal joints etc what could this problem be? I'm sure I'm not the only Yukon with this problem! GM must know what this is.
Submitted: 4 months ago.
Category: GMC
Expert:  rpmdiag replied 4 months ago.

Hi, welcome to Just Answer. I’m Ron and I’ll be helping you
today.
Before we get started though, Please understand that I don't know
your skill level or tools you have to assist us. Also understand that
I can't see, smell, hear, or touch the vehicle either, so patience is
appreciated. JA is a great Q/A site, but it does NOT replace a
repair shop.
My goal is to make you happy and get a great rating in return for
my time. Sometimes I have to give you bad news that I know you
didn’t want to hear, so please don’t shoot the messenger. They'll know what to do.

here is a TSB for that noise you're hearing.

Thanks , Ron

Customer: replied 4 months ago.
That's not it. I've changed entire suspension shocks and springs. This truck does not have leaf springs
Expert:  roybelding replied 4 months ago.

good morning my name is ***** ***** I will assist

has anyone check the rear motor mount?? very common for separating and jumping up and down during acceleration and deceleration.

Roy

Customer: replied 4 months ago.
More of a drivetrain clunk not motor mounts
Expert:  roybelding replied 4 months ago.

yes, I agree. the motor mount I am referring to is the transmission mount at the rear crossmember. when it separates, the transmission jumps up and down. very common failure due to the stress.

Roy

Customer: replied 4 months ago.
I don't think that's it. I have brought my truck to 3 different mechanics spending thousands. How do u check mount to see if it's bad? I've been under the truck many times. To me it's more of an inline cluck noise
Expert:  roybelding replied 4 months ago.

take a good long screw driver to the rear of the trans or transfer case. pry up using the cross member. see if it moves up and down. you can see the mount very easily

Roy

Customer: replied 4 months ago.
Wouldn't they have seen that when replacing transfer case?
Expert:  roybelding replied 4 months ago.

I cannot answer that. I am here and not there to look at it. they may have left bolts loose or the nuts securing the mount to the cross member

did you have the noise prior to replacing the transfer case???

Customer: replied 4 months ago.
This noise is what made me go to mechanic! Transfer case front differential ujoints suspension etc. still same problem
Expert:  roybelding replied 4 months ago.

I wish I could tell you more but I am here and not there to determine the failure.

I would still check that mount.

Customer: replied 4 months ago.
I'll check it now and get back to u
Expert:  roybelding replied 4 months ago.

I will be here

Customer: replied 4 months ago.
Mount is good! I didn't think it was that. It's a clunking thud when u first accelerate then when u lay off the gas pedal then accelerate again a thud or clunk noise. Do u work at a gmc dealer? GM must have some memos to dealers about this problem I can't be the only one 2003 GMC Yukon Denali AWD
Expert:  roybelding replied 4 months ago.

just checked and none found for this particular issue.

I will opt out and see if anyone else can help you further

Roy

Customer: replied 4 months ago.
Thanks. Hope we can find someone who knows about this issues with yukons
Expert:  Tom replied 4 months ago.

Quick question was a used differential installed?

Customer: replied 4 months ago.
No factory rebuild with 3 year warranty
Expert:  Tom replied 4 months ago.

Ok this happens more then you would ever think.Have they tried another differential as well as checked the driveshaft?

Customer: replied 4 months ago.
I will call and ask. How do they check the drive shaft? I'm very handy maybe I can check it
Expert:  Tom replied 4 months ago.

You can just go under the truck and move it up and down and forward and back if there is excessive play the u joints in the drive shaft are bad and thats your issue its actually very common and should have been checked.

Customer: replied 4 months ago.
No movement all u joints are brand new
Expert:  Tom replied 4 months ago.

No up and down movement at all ? Also if the u joints are not installed correctly it will also cause this issue .I would focus here and if that checks out I can almost garuntee the rebuilt deferential is bad . I would start here next .

Customer: replied 4 months ago.
This problem is before and after front diff transfer case and u joints were changed
Customer: replied 4 months ago.
How do u know if the rebuild is bad?