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Discussion Starter #1
Hello everybody,
I would like to know your thoughts about the following issue i am having with my CTS. After driving the car for about 10 mins, I hear a humming sound coming from the back when I press the accelerator slightly!! My brother and i were thinking it is either the back axle differential(?) or the exhaust system? By the way, the humming sound goes away if i move my foot off the acceleration padle.

At another forum (yahoo groups) a guy said that he also noticed the same issue, however it disappeared after replacing his exhaust with a modded dual exhaust system.

What is your input on this issue? please let me hear it.

Thanks a lot.
 

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Welcome aboard, Samari! And thank you for signing up.. Well, if it's happening after about 10 minutes of driving, it's probably something heating up.. I guess exhaust would be a good possibility.. I don't have any definite answers but I think someone will pop in and have heard of this - or experienced it - shortly...
 

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Sounds like the rearend. Take it to the dealer before any further damage is done. Might be low on gear oil.
 

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Discussion Starter #4
I took it in today for first 10K check up, they should be able to let me know what is going on. I hope at least they can diagnose the issue!!
 

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Two things i think it could be, i had a similar problem with the car just not sounding right, it could be that your wheels are screwy, or more likely the exhaust, i took it to the dealer several times but in their incompetence they never figured it out, either way i modded the car pretty heavily and am without either one....(new 18inch wheels and dual exhaust)
 

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ok finally the issue was fixed,
i took the car to 10K service and they checked the issue. They found out that the differential oil is down. I asked them if it was leaking, and they said no it is because the car was idle for long time. Well, this did not convince me. I asked them to keep the issue in the system so that they know i suffered from this problem when the car is still new.

Now the sound is gone and ll is well :) thanks to those who shared their thoughts.


Saeed
 

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samari said:
Hello everybody,
I would like to know your thoughts about the following issue i am having with my CTS. After driving the car for about 10 mins, I hear a humming sound coming from the back when I press the accelerator slightly!! My brother and i were thinking it is either the back axle differential(?) or the exhaust system? By the way, the humming sound goes away if i move my foot off the acceleration padle.

At another forum (yahoo groups) a guy said that he also noticed the same issue, however it disappeared after replacing his exhaust with a modded dual exhaust system.

What is your input on this issue? please let me hear it.

Thanks a lot.
I think it's probably in the drive train and would be supprised if the exhaust had anything to do with it. My CTS has started this noise as well. It is the same noise I have in the drive train from my Dakota Quad Cab. That's a $20K truck, and I don't expect it in my $40K plus luxury car! My dealer would not do anything about my noise -- YET. After I show him the posts here, maybe I can get him to finally do soemthing about it!
 

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MatthewsNH said:
I think it's probably in the drive train and would be supprised if the exhaust had anything to do with it. My CTS has started this noise as well. It is the same noise I have in the drive train from my Dakota Quad Cab. That's a $20K truck, and I don't expect it in my $40K plus luxury car! My dealer would not do anything about my noise -- YET. After I show him the posts here, maybe I can get him to finally do soemthing about it!

Just to follow up , the noise is back. I took the issue to GM regional office. They said they will get back to me within 48 hours. Plus i setup a meeting with service manager. I have to go through all this to fix a new car!!

When i first got the car i had noise in the brakes. After 2 visits and 11K km later, the noise still there. So much for the service! I will keep you updated.
 

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Discussion Starter #10
Well finally the dealer admitted that the sound is coming from rearend axle after having a technician ride the car with me and setting in the back. They are now ordering the parts from the states and should be in place within a month. again thanks for those who shared their thoughts with me

saeed
 

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Finally Fixed

Well dealer finally came thru and changed my differential axle and it is now like new. No humming No Noise !!

i saw somewhere that also in the states one dealer in Arizona is changing around 3 cars a week for the same issue.

In any case the issue was finally fixed and thought of updating.

Back to my ride :)
 

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Hmm interesting I ran acorss this forum. My '03 CTS just started to have this noise. the noise goes away if I step off of the accelerator or if I accelerate. If I keep the car at aprox 50Mph I get the noise. Its like a low frequency rumble. I will take it in to get it checked out.
 

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very interesting, i have seen this issue more then a few times now.......usually the rear axle requiring replacement.....

samari you said they had to order the parts from the states where your from?
Also im giving you some reputation points for a good thread
 

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I dont know where GM sources its differential parts from, but this is a constant and disturbing problem with Chrysler truck products. Grand Cherokees suffer heavily from axle whine and groan on the rear AND front axle components after only 40 or 50k miles, the differentials from DANA need constant attention and are probably the number one part to check when purchasing a used GC. It does not surprise me that other american brands suffer from diff issues as well.
 

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I had this problem then it disappeared. It's possible the dealer filled the differential oil during my recent oil change.

They also replaced the recalled Goodyears.
 
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