Slight "thud" on moderate accel from standstill

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Bucky1

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2011 Yukon Denali awd
From a stand still, if you accelerate moderately there will be a slight thud. I can't identify where it is coming from. I checked to see if the spare tire was loose. It wasn't. Is this anything common?
 

iamdub

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Remove the marble from the pocket in your door panel. :p

My guess is it's the ever-so-common driver's side engine mount. Pop the hood and watch the engine through the gap where the back of the hood meets the cowl. Hold the brake firmly and, with the trans in D, give the throttle a sharp jab. See if the left side of the engine jumps considerably and has a corresponding thud. Confirm by checking underneath for a rust-colored chalky substance all around and on the engine mount(s).
 

Doubeleive

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You can also look under the truck at both your front and rear sway bars and end links, see if one is broken or missing, if one is it will move every time and smack under the body
 
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Bucky1

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Doesn't seem to be the motor mount. Saw some posts on that and the engine doesn't move.
 
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Bucky1

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I was just under there, I will chekck the sway bars. I heard something about driveshaft clunk?
 

iamdub

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I was just under there, I will chekck the sway bars. I heard something about driveshaft clunk?

I was just about to say to grease the slip yoke splines. Does it seem to do it only once when accelerating after you've braked to a stop?
 
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Bucky1

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I was just about to say to grease the slip yoke splines. Does it seem to do it only once when accelerating after you've braked to a stop?

Yes it does. About the time the truck starts to rock back, and the tires starting to turn you hear/feel it.
 

iamdub

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Yes it does. About the time the truck starts to rock back, and the tires starting to turn you hear/feel it.

Classic slip yoke binding when braking then breaking loose when you let off the brake or accelerate. It's quick and easy to remove the shaft and grease the splines to at least rule that out as a cause.
 
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