Ok, I have an 05 Cobalt SS/SC with about 25,000 miles. For the past few months I have heard a loud kind of clanging noise coming from rear. I only hear it after I get off the highway from being in higher gears and decelerate. When I come to a complete stop I hear a banging noise. The car has been to the dealer once for this particular complaint, but of course they said they didn't hear it. Anyways, if anyone could help me I would appreciate it. Thanks.

 

Does it sound like something loose and banging around? Hard to say but that suspension is pretty simple in the rear, not much to it.

 

I don't think so......I think the dealer would have found that when they looked at it. And wouldn't it do it all the time?

 

go to the dealer and go for a drive with a tech in the car..replicate the problem and they will fix it under warranty....they can't fix something if they don't know what it is or can't replicate it

 

I would have to go 25 minutes away from the dealer to get up to those speeds. I don't think the mechanics are gonna wanna take a road trip. LOL I was hoping someone on here had the same experience so I could tell them what to look at and fix it finally.

 

Do you have anything on the rear? Rear sway bar? Anything like that?

 

o ok...NJ sucks...lol...jump on the turnpike or somethin maybe?...theres nowhere to get up to speeds in nj towns

 

Check your exhaust hangers,and wiggle the exhaust side to side and front to back .
The clanging you hear and the bang is most likely your exhaust clanging on a heat sheild and flexing back when you stop creating the bang.
Also a wore out motor mount could cause it in my opinion due to excessive flexing.

But the mian culprit would be the exhaust shifting from the deceleration !

 

Maybe its the license plate! Tighten up the screws

 

what does it sound like?...does it clang as your decelerating or when you are completely stopped?...i'm thinking maybe check your spare tire compartment see if anything is loose an hangin round in there and check and make sure everything is snug and well in the rear underbody as well....more info the better

 

It clangs very loudly after I have been on the highway in the higher gears when I slow down. It stops when I speed up again.

 

check that your tires are fastened properly via the lugs

 

i bet its your heat shield loose or something...that makes an incredibly annoying noise...is the exhaust louder that when you first got it?. if it is then maybe you blew out your cat an pieces are in your muffler clangin.

 

I have it to, a lot of people on g5club.net have it, its on our left passenger side, its the door to our gass tank. Sence theres no lock on it it will clink every once in a while, i get it a lot when i come off of a highway.

when you speed up again, the wind prevents it from comming back up again

 

mine does the same thing, i always look to see if anyone is knocking on my trunk out of instinct. I work at a chevrolet dealership and i have never seen one come in for that and i cannot figure out what it is.

 

i too have heard this noise, maybe twice total.

It is exactly as you describe. It sounds like someone is knocking on the rear of your car.

Ive only had it happen when coming out of reverse. In fact havent heard it for months.

would love to figure what it is exactly.

 

Did you lock anybody in the trunk?

 

mine does it when i turn off the car and a few sec or mins later i hear it
the first time it happen check my trunk too see if some one was in there

 

If its a knocking noise like someone at the door its normal . Its the EVAP system IIRC. GM put a bulletin out for it and said its normal operation.

 

I hear the noise your saying all the time (3-5 tap noises)when doing something slow like sitting idle or backing up. It also does it alot just after I shut off and get out. I heard that GM says it's the fuel system or something. I'd say it's far from a loud clank though. I think that is a seperate issue.

 

ya i think the OP has a seperate issue. But good to hear its normal.

Thanks for the info about it.

 

still having this issue?

 

Ok....I am not talking about the knocking sound when I turn the car off. I figured that was normal and didn't worry about it. LOL This other noise was different. I am not sure if the car is still making to noise or if my radio is just too loud. LOL I haven't heard it in awhile.

 

i got a problem from the rear also, when i come to a stop i hear knocking from the right rear of the car, and then when i turn off the car i hear KNock KNock Knock.

 

When do you hear it? Notice that the car does not run any differently?? Strange......might be another Cobalt quirk.