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2005 chevy trailblazer_ls
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Discussion Starter #1
So let me describe whats happening. Ive got a 2005 Trailblazer LS with the 4.2ltr engine.It rides & sounds normal on smooth roads regardless of speed.However,when you're driving through potholes or hitting any type of bump period,you can hear a loud rattling noise near the rear.If you were to loosen a couple bolts on a metal bracket and then drive over some bumps,thats what the noise sounds like or possibly the exhaust banging against something.Ive tried wiggling the exhaust from the axle housing back,but it didnt move or hit anything.One thing I did notice though is the rubber exhaust hanger at the passenger rear.You know how they take a solid piece of rubber then cut a hole in the lower part of it (that the exhaust pipe hanger rod fits into)
then cut more sections of the rubber out?? The lower hole, on my rubber hanger,is completely torn apart so the previous owner just moved the exhaust pipe hanger rod up and slide it into the rubber cutout thats higher up on the hanger.This doesnt allow the pipe to move at idle,but if the vehicle is moving and hitting potholes,could that cause the exhaust pipe to hit a body or suspension part when the shocks compress??
Ive read that the swaybar endlinks can cause rattling noises,so whats the best way to check this??
Can I just remove the nut from the top stud of the endlinks,pull it out of its mounting hole then take the TB for a short test drive to see if the noise stops??
This noise is driving me crazy.
 

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2007 chevy trailblazer_lt
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8 Posts
Get under the back once is cool and start grabbing things to see what moves

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2005 chevy trailblazer_ltz
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Rattling Noise from Rear Axle

So let me describe whats happening. Ive got a 2005 Trailblazer LS with the 4.2ltr engine.It rides & sounds normal on smooth roads regardless of speed.However,when you're driving through potholes or hitting any type of bump period,you can hear a loud rattling noise near the rear.If you were to loosen a couple bolts on a metal bracket and then drive over some bumps,thats what the noise sounds like or possibly the exhaust banging against something.Ive tried wiggling the exhaust from the axle housing back,but it didnt move or hit anything.One thing I did notice though is the rubber exhaust hanger at the passenger rear.You know how they take a solid piece of rubber then cut a hole in the lower part of it (that the exhaust pipe hanger rod fits into)
then cut more sections of the rubber out?? The lower hole, on my rubber hanger,is completely torn apart so the previous owner just moved the exhaust pipe hanger rod up and slide it into the rubber cutout thats higher up on the hanger.This doesnt allow the pipe to move at idle,but if the vehicle is moving and hitting potholes,could that cause the exhaust pipe to hit a body or suspension part when the shocks compress??
Ive read that the swaybar endlinks can cause rattling noises,so whats the best way to check this??
Can I just remove the nut from the top stud of the endlinks,pull it out of its mounting hole then take the TB for a short test drive to see if the noise stops??
This noise is driving me crazy.
Hi
Check your parking brake liners. Sometimes they get loose and start making this noise.
 

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2008 chevy trailblazer_lt
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76 Posts
Grab the roof rack towards the back and rock the truck side to side real hard and listen for a clunk clunk. That's how I found out my rear end links were bad.
 

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2006 chevy trailblazer_ls
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2 Posts
For my '06, it was a rear sway bar link. It didn't budge when I tried to shake it, but I had somebody drive while I looked down at it and sure enough it was loose. Tightened up the bolt by sticking a big allen wrench in the middle and tightening the nut with an open end wrench. No more rattling.
 

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2005 chevy trailblazer_ls
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35 Posts
Same exact problem here. Replaced sway bar ends and it's still there. Everything else is solid.

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2005 chevy trailblazer_ls_ext
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13 Posts
For me I changed my rear differential fluid with a mix of Mobil 1 synthetic 75w90 and Supertech 75w140 full synthetic. No more noise from rear.
 

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2005 chevy trailblazer_ls
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For me I changed my rear differential fluid with a mix of Mobil 1 synthetic 75w90 and Supertech 75w140 full synthetic. No more noise from rear.
My rear diff fluid is due, but this sounds more like nuts and bolts in a coffee can.

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2004 chevy trailblazer_lt
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572 Posts
Have you checked the shocks and mounts or the exhaust system hangers?
 

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2005 chevy trailblazer_ls
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Discussion Starter #11
Did you ever find out what is was rattling?
Sorry,I know its been awhile since I posted this thread,but I wanted to update it for future reference to anyone who needs it.As a test,I removed the driver rear swaybar endlink then took it for a test drive.The noise disappeared,so I went to the parts store and bought a new end link and installed it and months later,the noise has not reappeared.So if anybody is experiencing the same symptoms I was,buy a new endlink for each side,remove the endlink on the driver & passenger side,take it for a test drive and if the noises stop,go back to the house and install the new links.If the noises are still there,once the test drive is done,reinstall the old links,return the new links to get your money back and continue trouble shooting the problem.
The stud on each end of the endlink has a allen head recess in it that you have to hold with an allen wrench while
removing the nut with a separate wrench. Soak the studs good with pb blaster or wd40 a few hours before you start removing the link.
 

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2006 chevy trailblazer_lt
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11 Posts
That endlink on drivers side is a bitch with the gas tank in the way. Took me twice as long for that side as it did for passenger. Replaced sway bar bushings while I was down there. Moog end links for both sides and new bushings all shipped from Rock Auto for under $60 (noise is still there) Will check exhaust system hangers and emergency brake liner next.
 

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2005 chevy trailblazer_ls
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Discussion Starter #13 (Edited)
That endlink on drivers side is a bitch with the gas tank in the way. Took me twice as long for that side as it did for passenger. Replaced sway bar bushings while I was down there. Moog end links for both sides and new bushings all shipped from Rock Auto for under $60 (noise is still there) Will check exhaust system hangers and emergency brake liner next.
Yeah that's why I didn't replace any parts to verify if they were the cause or not.My plan was to remove one part at a time (starting with the driver rear swaybar endlink) then take it for a short test drive to listen to the results from that part deletion & fortunately,the very first part I removed was the cause.I also used this method so I would know which part was defective & the type of noise it caused for future trouble shooting.IOW- if I would have replaced 4 or 5 components,took it for a test drive and the noise had stopped,I'd be happy that the noise had gone away,but it still wouldn't have told me which part was at fault.Now I realize there are duplicates of some parts,like the endlinks/swaybar bushings/wheel bearing hub assemblys/etc, and if the part is defective on one side of the vehicle,the chances are probably high that the duplicate part (on the opposite side of the vehicle) isnt too far behind on going bad too,so if this is the case it wont hurt to go ahead &
replace the duplicate part too.However,for the purposes of trouble shooting this type of problem, I prefer using the 1 part removal/1 test drive method.

Some of the other parts I checked,before ultimately deciding to pull the endlink,were
the metal exhaust system shields(next to the spare tire),the hoses coming from the carbon canister,the spare tire retainer mechanism(if the rim/tire arent present or theyre present but the tire is not seated tightly against the body recess under the vehicle because the mechanism is loose),the parking brake cable/ mechanism at each rear wheel and any metal part/bracket you can find at the rear.
 

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2006 chevy trailblazer_lt
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Yeah that's why I didn't replace any parts to verify if they were the cause or not.My plan was to remove one part at a time (starting with the driver rear swaybar endlink) then take it for a short test drive to listen to the results from that part deletion & fortunately,the very first part I removed was the cause.I also used this method so I would know which part was defective & the type of noise it caused for future trouble shooting.IOW- if I would have replaced 4 or 5 components,took it for a test drive and the noise had stopped,I'd be happy that the noise had gone away,but it still wouldn't have told me which part was at fault.Now I realize there are duplicates of some parts,like the endlinks/swaybar bushings/wheel bearing hub assemblys/etc, and if the part is defective on one side of the vehicle,the chances are probably high that the duplicate part (on the opposite side of the vehicle) isnt too far behind on going bad too,so if this is the case it wont hurt to go ahead &
replace the duplicate part too.However,for the purposes of trouble shooting this type of problem, I prefer using the 1 part removal/1 test drive method.

Some of the other parts I checked,before ultimately deciding to pull the endlink,were
the metal exhaust system shields(next to the spare tire),the hoses coming from the carbon canister,the spare tire retainer mechanism(if the rim/tire arent present or theyre present but the tire is not seated tightly against the body recess under the vehicle because the mechanism is loose),the parking brake cable/ mechanism at each rear wheel and any metal part/bracket you can find at the rear.
____________________________________________________________

I have tried looking at just about everything I can. This sound or rattle is ONLY audible when the TB hits a bump or dip in the road. I checked the emergency brakes and that is not the issue. It's driving my wife nuts so it's indirectly driving me nuts. If anyone has any other suggestions I'm all ears... at this point I'm almost ready to take it somewhere and see if they can find it.:bonk:
 

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2005 trailblazer_lt
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112 Posts
A bad sway bar end link is (obviously ! ) a very common reason for a rear end suspension rattle, probably the #1 cause in most cases. Here's 4 other things I found making a rattle in the driver rear area of my 05,....

1: Fuel tank neck plastic line; The fuel system changed from 04 to 05 and the 04 didn't have this small plastic line on the fuel neck. Zip Tied it to the neck in a coupe places and that rattle was gone.

2: Running board; 1/2 of the tabs on the rear of the drivers side running board were deformed causing the running board to rattle when driving over rough roads. I jammed a golf tee thru the center of the rear-most plastic tab to enlarge it and now it holds firm and that rattle is gone.

3: Driver rear fender liner/mudflap; one of the screws was a little loose causing the fender liner to become loose and caused a slight rattle against the body metal. Can't say I ever heard this while driving, but it was apparent when diagnosing the problem.

4: Parking brake lever on backing plate; Almost didn't notice this,... I found the cable was secure and almost moved on, but then noticed that the itself was very loose and would rattle when moved by hand. I haven't resolved this yet, but you can probably check this by finding a rough road to re-create the rattle,... then pulling the E-Brake handle just a little bit and drive over the same rough patch to see if the rattle goes away when the parking brake is JUST BARELY engaged.

Hope this helps !


:cool:
 
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