Jackhammer sounds from under front end and other horrible noises - 2008 Yukon Denali

swathdiver

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I had the entire truck gone over by a GMC dealer an they can't find a blessed thing wrong with it. The front stabilizer bar links were bad (bushings gone). Replaced them and the problem got worse. U Joints OK, the crossmember is ok. Transmission and transaxle OK. No problem can be found.

The banging is getting even louder. After replacing the bar links and the mounts and checking the crossmember for looseness; checking the drive line for bad U joints, and everything else the mechanics can thing of, the issue is getting worse.

After I replaced the links on the bar (the old ones were flopping loose) I got a repeated banging noise on backing out of my driveway and then a minute later as I drove off down the road. The banging was loud enough to echo off the trees in the woods. Just like someone was hitting the underside of the Yukon with a hammer. Then it stopped.

I drove about 12 miles to my horse barn, parked the Yukon for about 30 minutes to feed the horses. On backing up, BANG BANG BANG!. Then it stopped. Then it was BANDG< BANG BANG down the driveway until I got on the road. There was a brief scraping noise this time when I turned to the right (it was always on the left) and the problem stopped. The problem always starts on the straight on a smooth road only. If, upon the banging I throw the vehicle into neutral, the banging continues. No feedback through the steering wheel or any change in vehicle performance. Just a nasty, loud (and I mean nasty LOUD) banging and you can feel through the floor of the vehicle.

Again, U Joints are fine, Everything in the front end is tight and at specs, Driveline and everything else are fine. The only thing is that the problem is got very much worse and more persistent after I replaced the stabilizer bar links. It sounds like something is about to break. And I am at wits end trying to figure this one out. The dealership is totally stumped.
They have a set of sensors they could have hooked up that would isolate the noise. I forget what it is called. Do you have a Go-Pro or something similar? Some fellas even tape their cameras underneath and make a short drive to isolate the sound.

I'm still thinking the ABS Pump, could be the AC Compressor. Did anyone specifically say that they checked the 3 torque converter bolts that connect the converter to the flex plate? When loose, they sound like the motor is coming apart.
 

Doubeleive

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I had the entire truck gone over by a GMC dealer an they can't find a blessed thing wrong with it. The front stabilizer bar links were bad (bushings gone). Replaced them and the problem got worse. U Joints OK, the crossmember is ok. Transmission and transaxle OK. No problem can be found.

The banging is getting even louder. After replacing the bar links and the mounts and checking the crossmember for looseness; checking the drive line for bad U joints, and everything else the mechanics can thing of, the issue is getting worse.

After I replaced the links on the bar (the old ones were flopping loose) I got a repeated banging noise on backing out of my driveway and then a minute later as I drove off down the road. The banging was loud enough to echo off the trees in the woods. Just like someone was hitting the underside of the Yukon with a hammer. Then it stopped.

I drove about 12 miles to my horse barn, parked the Yukon for about 30 minutes to feed the horses. On backing up, BANG BANG BANG!. Then it stopped. Then it was BANDG< BANG BANG down the driveway until I got on the road. There was a brief scraping noise this time when I turned to the right (it was always on the left) and the problem stopped. The problem always starts on the straight on a smooth road only. If, upon the banging I throw the vehicle into neutral, the banging continues. No feedback through the steering wheel or any change in vehicle performance. Just a nasty, loud (and I mean nasty LOUD) banging and you can feel through the floor of the vehicle.

Again, U Joints are fine, Everything in the front end is tight and at specs, Driveline and everything else are fine. The only thing is that the problem is got very much worse and more persistent after I replaced the stabilizer bar links. It sounds like something is about to break. And I am at wits end trying to figure this one out. The dealership is totally stumped.
make a video of the sound and post it up on youtube, then post the link to the video here
 

Gildan

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make a video of the sound and post it up on youtube, then post the link to the video here
If I can get it to do it on queue. The best description is it sounds like someone beating on a steering knuckle with a hammer. Happens on turns and on the straight and lasts only for about a minute or two, and at random and then stops. It's almost like something is loading up and releasing. At first I thought it was a CV joint about to break, but the joints are OK.
 

Doubeleive

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If I can get it to do it on queue. The best description is it sounds like someone beating on a steering knuckle with a hammer. Happens on turns and on the straight and lasts only for about a minute or two, and at random and then stops. It's almost like something is loading up and releasing. At first I thought it was a CV joint about to break, but the joints are OK.
if you can catch it on video there is a good chance one of us will know what it likely is
 

ivin74

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If I can get it to do it on queue. The best description is it sounds like someone beating on a steering knuckle with a hammer. Happens on turns and on the straight and lasts only for about a minute or two, and at random and then stops. It's almost like something is loading up and releasing. At first I thought it was a CV joint about to break, but the joints are OK.
Have you checked the rack and pinion?
 

Gildan

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I checked the rack and pinion and every other part known to man and God. Mechanics did also at great expense. No clue what it is causing this, but it sounds like something is going to let loose and bust when it happens.

The only thing I know so far is that it got worse the instant I replaced the links on the stabilizer bar in the front. It occurs at random and will never occur when I have the camera rolling. But it sounds like something is going to go bust.

I'm am going to call the GM dealership again and ask them WTF?! They can't even figure it out even after replacing half the Yukon and the problem still persists.
 

ivin74

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I checked the rack and pinion and every other part known to man and God. Mechanics did also at great expense. No clue what it is causing this, but it sounds like something is going to let loose and bust when it happens.

The only thing I know so far is that it got worse the instant I replaced the links on the stabilizer bar in the front. It occurs at random and will never

I checked the rack and pinion and every other part known to man and God. Mechanics did also at great expense. No clue what it is causing this, but it sounds like something is going to let loose and bust when it happens.
Put the suv on 4 jack stands, remove the wheels and have someone put it on gear while you inspect the noise. Make sure you put the front jack stands on the control arms and the rear jacks on the differential. You don't wanna change the geometry. This will get you the results you need.

I've done this with very successful results in the past.
 

Gildan

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The only thing that makes noises like that is the ABS pump. Which is on the other side of the car, driver's side. Sound travels.
OH! I figured out what it was!

It turned out to be a bad front wheel bearing. The banging was was the sound of the bearing in the hub assembly failing. At first, the failure was not bad enough to show any play in the front bearing. Yesterday I heard the distinct sound of a spun bearing, so we put it up on a lift and checked the bearing again - the bearing totally gave out and literally was sliding in an out about 1/4 inch the second time it was checked. Mystery solved.
 

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