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Discussion Starter #1
Hey. I got a 2004 Envoy. It's my son's. He said he was driving home and suddenly felt a big "thunk" type sound coming from the back.

I drove it around the block and sure enough, don't really quite know how to describe it other than a thunk sound coming from the rear. Noticed it mostly while turning to the right but it drove straight and engine seemed fine. Something perhaps in the drivetrain? It sounds internal to me. Looked underneath and saw nothing obvious hanging or broken or anything.

Any ideas where to start looking?
 

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Discussion Starter #3
Thank you. Will check tonight when I get home. With a bad u v joint with the car still drive just fine for a little bit? I'm not going to drive it I was just worried about him driving at home last night.
 

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2004 GMC Envoy SLT 4.2
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If a U joint is bad enough to clunk , it likely isn't far from letting go , totally .
There's a fairly high amount of pressure passing through that joint .
 

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2002 chevy trailblazer_ltz
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Drive shaft u joints.
Drive up a hill that you can put a load on it. Some torque. Then down the hill giving light gas but not all the way off.

Lastly if it's really bad when starting from a stop go hard on the accelerator. If you've a really bad u joint it will clunk then.

If no noises in the above scenario it's not bad enough to worry about yet.

There are also rear sway bar and drop kinks back there. If bad they'll clunk

Good luck
 

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Discussion Starter #6
I climbed under there last night just to visually look at the U joint. It seemed pretty solid. I'll check the sway bar see if he has any play to it. I'll give it a chance to check out that U-joint this weekend. I appreciate the response
 

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2007 chevy trailblazer_ls
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Hey. I got a 2004 Envoy. It's my son's. He said he was driving home and suddenly felt a big "thunk" type sound coming from the back.

I drove it around the block and sure enough, don't really quite know how to describe it other than a thunk sound coming from the rear. Noticed it mostly while turning to the right but it drove straight and engine seemed fine. Something perhaps in the drivetrain? It sounds internal to me. Looked underneath and saw nothing obvious hanging or broken or anything.

Any ideas where to start looking?
Look at your trailing arms. I ended up with 2 broken welds at both upper trailing arms one morning. I was able to limp home the weld them up since I have a welder. Arms are generally not available over the counter. DO NOT DRIVE THE VEHICLE! The arms are not that difficult to R/R, but you have to get them first.
 

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2004 buick rainier
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My son's Cadillac CTS '07 rear-wheel drive had a similar sound. There was a bushing on the rear differential that had basically disintegrated in place. Easy and not too expensive replacement/repair. We could repeat the clunking sound by, as we are driving, coast for a little while by taking the foot off the gas, then resume pressing the gas pedal: clunk. Perhaps similar issue for you.
 

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Discussion Starter #9
Thanks. Kinda isolated the sound from behind the drivers side wheel. Have yet to pull it off and look it all over. Appreciate the feedback.
 
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