Light Rattling from the Rear

Was my rattle just a snow brush bouncing around?


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    5

l008com

Hobbyist
Original poster
Feb 19, 2016
712
Massachusetts
For the past month or two, I've been having a lot of rattling coming from the back of the truck. I can't tell if it's inside or outside. It's not a heavy rattle, it doesn't sound like a load bearing suspension part. But it happens whenever the rear axle hits a bump, even a small bump like a large crack in the road.

So last night I was putting my crow bar away and when I flipped the seats up, there was my winter snow brush under there. Most likely bouncing around with every bump. So I took it out and just threw it on the rear floor.

Tomorrow I drive into the city for work, we'll see if I fixed the rattle or not :biggrin: What do you think?
 

Mooseman

Master Blaster
Moderator
Dec 4, 2011
22,325
Ottawa, ON
Stab bar end links.
 
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l008com

Hobbyist
Original poster
Feb 19, 2016
712
Massachusetts
So it wasn't the snow brush.

So I put the truck up on ramps and got under there and shook everything i could shake. Everything was tight. Even the end links. Keep in mind this sound I'm hearing isn't a hard clunk. It's a very light rattle when the rear tires hit bumps, it sounds plasticky.

After no luck under the truck, I went through my cargo bays and removed some more junk that could be rattling around.

I'm still getting the noise. Nothing I do seems to have any affect. I don't know what else to check, I'm open to suggestions.
 

Blckshdw

Likes lights and stuff
Moderator
Nov 20, 2011
10,228
Tampa Bay Area, FL
If everything feels tight, the only other things I can think of would be to have someone drive your truck on some of the bumpy surfaces while you lay in the cargo area and listen to better pinpoint where the noise is coming from. If you aren't able to get an assistant, the more expensive version of that would to buy some "chassis ears" :twocents:

 
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Mathoran

Registered Member
May 3, 2012
49
Try hitting your rear tires with a rubber mallet and see if you can reproduce the noise and pinpoint it. check that your spare is tight or maybe rear hatch/glass is moving around.
 
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l008com

Hobbyist
Original poster
Feb 19, 2016
712
Massachusetts
... have someone drive your truck on some of the bumpy surfaces while you lay in the cargo area and listen to better pinpoint where the noise is coming from...

I've thought of that actually but I haven't had the opportunity to actually do it yet. Hopefully soon I will.

...check that your spare is tight or maybe rear hatch/glass is moving around.

That's almost what it sounds like, but I do open the rear gate often and I haven't noticed any unusual sounds when I slam it closed.

Check the rear heat shield, mine rusted through and was rattling around
I literally grabbed every single thing under the truck and tried to move it hard.
 

Chickenhawk

Hobbyist
Dec 6, 2011
730
Next time you are underneath and the engine is cold, hit the cat convertor with your fist. If the internals start breaking apart, that's exactly the sound it makes.
 
Last edited:

l008com

Hobbyist
Original poster
Feb 19, 2016
712
Massachusetts
Is that supposed to say catalytic converter? If so, I don't think so. The sound is *almost* definitely coming from the rear of the truck. Plus that cats on the V8 are tucked up high aren't they, kind of out of reach? I need to have my cousin drive around with me in the back, I think that's the only way. I'll poke around with it more tomorrow and see if I can come up with anything. It's finally getting warm out, that should help.
 

Blckshdw

Likes lights and stuff
Moderator
Nov 20, 2011
10,228
Tampa Bay Area, FL
Will I be able to with the wheels hanging, like if I jack up by theframe or by the diff?

Basically you need to take the load off of the suspension parts. That will give them more freedom to move, if they are the problem children here.
 

TollKeeper

Platinum Donor
Dec 3, 2011
6,711
Brighton, CO
I think what he is saying is by the frame rails. You want the suspension hanging, so its in its loosest fashion.
 

l008com

Hobbyist
Original poster
Feb 19, 2016
712
Massachusetts
Jacked it up tonight, supposed by the frame rails. Let the hack down. Rear axle was hanging, everything seemed nice and tight.

Except for one thing, which is something I mentioned in another post. The wheels/axle ends move in and out a tiny bit. It's not much, but its enough to be able to push them in and out by and and get them to clunk a bit. One side does it a bit more than the other. It's probably only like 1/8" of movement, approximately. But its enough to clunk. And I'm not sure if that's the noise I'm hearing while I'm driving but it seems to fit.

And EVERYTHING else is super tight. Including the rear swaybar end links. I couldn't get a bit of movement out of them. I was hoping it was them, thats a very easy fix. I don't think it's the bushings, it's not a squeak/squeal kind of noise like the front get when they're dry. It sounds like something small bouncing around in a plastic box. Which is kind of the sound the rear axle ends make when they're moving a tiny bit in and out.
 

TollKeeper

Platinum Donor
Dec 3, 2011
6,711
Brighton, CO
My Envoy and 9-7x does the same in/out movement. No worry there.

This may seem far fetched, but its an easy, and free check..
Check the transfer case fluid level, and fluid condition
Do the same for the rear axle

I am wondering if it might not be axle chatter from low, or worn fluids
 
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tokanero

Newbie
Mar 15, 2021
4
Maryland
Hmmm...maybe check the FRONT links. They made a clunking rattle on my 2004 after I thought I fixed everything by tightening up the rear links. I could tell mine were loose just by looking at them. You could see a bright wear ring where the bushing rubs the frame.
And another thought...see if you can tighten up the rear shocks. Another area that made noise on mine.
 

Mooseman

Master Blaster
Moderator
Dec 4, 2011
22,325
Ottawa, ON
Sound can travel in weird ways in a vehicle. Something you think is coming from the back could be coming from the front and traveling to the rear. Check everything.
 
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TequilaWarrior

Active Member
Dec 5, 2011
454
Central Pennsylvania
Jacked it up tonight, supposed by the frame rails. Let the hack down. Rear axle was hanging, everything seemed nice and tight.

Except for one thing, which is something I mentioned in another post. The wheels/axle ends move in and out a tiny bit. It's not much, but its enough to be able to push them in and out by and and get them to clunk a bit. One side does it a bit more than the other. It's probably only like 1/8" of movement, approximately. But its enough to clunk. And I'm not sure if that's the noise I'm hearing while I'm driving but it seems to fit.

And EVERYTHING else is super tight. Including the rear swaybar end links. I couldn't get a bit of movement out of them. I was hoping it was them, thats a very easy fix. I don't think it's the bushings, it's not a squeak/squeal kind of noise like the front get when they're dry. It sounds like something small bouncing around in a plastic box. Which is kind of the sound the rear axle ends make when they're moving a tiny bit in and out.
That sounds like axle END PLAY.... which is completely normal and shouldn't be noticeable at all. Every GM rear end I've ever driven has the same end play (or worse). The only one that actually made a noise I could notice while driving completely destroyed the axle end seal and leaked diff fluid into the drum brake (we have disks, but it would still be noticeable).
 
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l008com

Hobbyist
Original poster
Feb 19, 2016
712
Massachusetts
Next time my cousin is around, ill try to get him to drive down some bumpy side streets and see if i can hear anything.
I drove the other day and it barely made a sound. It was the first warm day of the year. The sounds also goes away when the truck warms up usually, which makes me think its something related to the exhaust system but i shook and punched everything i could find under there and nothing made any sound at all except the axle. I'll see what I can come up with.
 
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