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Rear end knocking '08 G6 Sedan

6K views 7 replies 5 participants last post by  spicerg6 
#1 ·
Hi All. I've read through a number of threads talking about this issue and may be getting closer to a solution but not yet!

When I drive over even the smallest bumps in the road theres a knocking in the back. Sounds like its coming from the trunk area.

Here's what I've done so far:

Replaced the shocks
Checked all suspension connections with car fully lifted off the ground
Sway bar and links/bushings
replaced the rear bumper after a rear-ending. they also had to reshape some of the trunk area, but still, after all that, the knocking remains.
Checked wheels
Checked the spare tire/jack.
Moved the trunk felt around.
Pulled down the rear seats (to find out if it was the latch and to hear the knocking better).

Its definitely under the trunk. I've checked just about everything, shook things, etc etc. It only happens while im driving. shaking the car up and down and side to side does not reproduce the sound.

Someone mentioned a place where the trunk and bumper and muffler meet, but not sure what they mean as the muffler hangs down off some rubber deelies that also do not reproduce the sound.

Does anyone have any ideas?
 
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#2 ·
continuing

I've pulled everything out of the trunk and any pieces that could be rattling.

Its definitely not in the trunk area. I've moved the plastics and stuffed paper towel against any plastics that could be knocking against each other, thats not it either. I replaced the shocks but not the shock mounts. Perhaps that is it? Anyone think that could be the cause?
 
#4 ·
Think i got it

Alright so the problem seemed to be getting worse and when I was putting my snow tires on I decided to check it out once more.

Forcing the rear sway bar up I was able to reproduce the knock.

So i picked up some new sway bar bushings and went to install them, as I believe this is the source of the issue.

Guess what... the bolt that holds them on broke off. I actually had to grab the acetylene torch to heat up one to get it off. When I got to the other one trying to loosen the bolt (on the opposite side from the one I torched) it actually snapped off. Now I have to take the whole rear end off basically to rebore and tap the hole to put a new bolt in. WTF... a 1 hour job just turned into easily a 5 hour job. GREAT
 
#6 ·
I have finally solved the rear end noise issue, well, maybe it was just my issue. My mechanic, dealership and a suspension shop had no luck in pinpointing my rear end clunking noise that sounded like my car was falling apart until today. I was shaking every part of the rear end to find out that all this time, that both my tail light assembly were loose. Each taillight has two nuts accessible from inside the trunk and now there is absolutely no noise in the rear end. Hope this helps someone else and I've had the vehicle since it was brand new and have never replaced a build in the back, so the nuts must work there way loose over time.
 
#7 ·
I have finally solved the rear end noise issue, well, maybe it was just my issue. My mechanic, dealership and a suspension shop had no luck in pinpointing my rear end clunking noise that sounded like my car was falling apart until today. I was shaking every part of the rear end to find out that all this time, that both my tail light assembly were loose. Each taillight has two nuts accessible from inside the trunk and now there is absolutely no noise in the rear end. Hope this helps someone else and I've had the vehicle since it was brand new and have never replaced a bulb in the back, so the nuts must work there way loose over time.
 
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