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High pitch whistle on acceleration

67707 Views 66 Replies 29 Participants Last post by  RKM
I have a '07 G6 GT that I inherited from my 87 y/o grandfather when he past away in January. Yes, it's red because what other color would an 87 year old man drive. Within the last 2 months I've started noticing a high pitch whistle/noise when I accelerate. If I back off the throttle its goes away. I thought it was brakes at first but I get no noise when I brake at any speed. Only when I accelerate. Anyone have any thoughts? Haven't brought it in yet, want to see if its a minor fix I can do myself.


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Whistling sound at 2500RPM

I've read hundreds of posts on it, but has anyone gotten rid of their whistling sound on their G6. It occurs when my G6 hits 2500rpm. I took it to the dealer and they said they want to put on an entirely new exhaust system for $600. I don't know how this isn't an manufacturers defect. Has anyone done this yet, and if so, does it truly get rid of the whistling sound. I rather not blow $600 if it doesn't get rid of that piercing sound.

Also, I've tried plugging the wheep hole in the muffler with a screw. It does nothing. I still got that whistling sound, so that's why I question this exhaust system so much. I also tightened all the connections on the airbox too.
Replace the resonator, use aftermarket, or it will come back.
Mine was fixed under warrantee a year ago. They replaced the entire exhaust and the problem went away. I can't say if it was the resonator or the weep hole but something in the system fixed it. I've now got about 14,000 miles on the exhaust and the whistle has not returned. If I were paying for the fix I would not get a stock one from the dealer. For the money I’m sure there are better aftermarket exhausts that cost a lot less if you are planning to replace the whole thing.

I just tried a new serpentine belt and new idler pulleys, no change at all so I guess I am going looking for a weep hole before I take it to the dealer.
I was surprised that the belt was not in stock anywhere, then I saw how long it is. I don't think I have ever seen one so long before..
Due to the dealer cancelling my after market warrantee ("oops it was a clerical error") I now have to wait 30 days for the coverage to take effect.
I replaced the pulleys, belts, front struts, new brakes all the way around and I still hear the whistling. I'm now convinced its the exhaust after seeing many others post the same thing. replace the exhaust sound goes away. My suggestion is look at after market exhaust systems and not a GM one as you will probably wind up with the same crap product again. Now is your chance to get some throat for your G6.
I'm going to Midas to have them take out the resonator and put in a Magnaflow 10425 Stainless Steel Straight Pipe Muffler. I'll post how it sounds when its done and if it fixes the problem.
I'm going to Midas to have them take out the resonator and put in a Magnaflow 10425 Stainless Steel Straight Pipe Muffler. I'll post how it sounds when its done and if it fixes the problem.
Thx - let us know - the squeal is driving me nuts - also tell us what you paid for the Magnaflow. Much appreciated.

Here's the link to the Magnaflow product info http://www.magnaflow.com/02product/shopexd.asp?zone=main&id=9246
Turns out that it on the 2007 G6 GT Convertible, its 2" in not 2.25". I went off of what someone said in another thread. Gotta wait until Saturday for the new 2" Magnaflow to come in. Ill post all info once its done and if it fixes it.

And as far as price goes, they are usually around 60 bucks on Amazon. It depends what length you go with as well, but its within a few dollars. Hopefully I get the part this weekend and can schedule something Monday. I'll let you know how it goes.
So Today I went to Midas. They cut off the old resonator, put in this new magnaflow 10424 for $130. My car has never sounded so beautiful. It is quiet and sounds perfect how it should have in the first place. Over all it was $130 for labor, but that's from Midas. You can get coupons and what not and negotiate better. And the Muffler was $60, so like $190 and all your problems go away. It sounds amazing at 2500rm and above.
post up sound clips!!! is it deeper at all? or just quieter
It definitely made it quieter. The hissing sound only occurred at 2500rpm. You can't hear it now that I replaced the resonator. Since I have 2 Mufflers now, there really isn't any tone at all. I'm not sure if they made the exhaust different on the convertible model or what not so it would sound more luxury. As far as sound clips, it wouldn't pay to post any as you really can't hear anything.
I have a '07 G6 convertible with 35,000 miles. I started to hear this high pitched squeeling noise upon acceleration as well. I took it to the dealership, and although I have the GMPP Major Guard extended warranty, it was not covered. At my dealership, they designate the same service person to work with you each time you bring your car in to get serviced. They get to become familiar with you and your car. I have never been more impressed with the customer service that I received. After they ordered the parts, my car was fixed in 1 day. This is what the invoice says.
1 19257426 F-Muffler
1 22734961 Gasket
2 11609746 Nut
3 55157 Bolt Kit
FC: Part# 19257426 Count:1
36109 FC 6065 Possible noise from resinator. Remove subframe to gain access to exhaust. Replace resonator and muffler assembly. Reinstall subframe.
My service advisor was able to replace all of this at no charge to me. It is called "goodwill" and he said something about sending the bill back to Pontiac. I seriously didn't pay 1 cent for any of this. He said he was able to do this since my car has such low mileage, and because he has seen this problem several times on their bulletin. Whatever that means. Hope this info. helps get your problem fixed for free!
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My entire exhaust was replaced.

I had this same issue around 33k miles. I have a 2008 Pontiac G6 GT Hardtop. They said it was common.
Hello everybody. I have had the same issue with my '09 G6 Convertible. They stated that there was a problem with the exhaust system (CAUSE: 9090 according to the Invoice), and they stated the following service and replaced the following parts:

L2584 Muffler Single Replace
19257426 Muffler
22734961 Gasket
CC: 0323
FC: 6063

After they replaced it the noise has gone away, but the exhaust tip is a smaller, to me it looks very strange being so much smaller than the original. Has this happened to anyone else? Is this normal? Here are some pictures:

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Whistle no more....

'07 G6 convert with 45K on it.

Whistled like a bottle rocket on acceleration from about 2k to 3k rpm, never at cruise.

Followed slls and ballerinda's examples and replaced the resonator with a MagnaFlow 10424 from Summit Racing ($68, free ship), 2" in and out, 24" overall, matched the factory resonator and it is stainless to boot.

It is now more better, no hint of a whistle, just V6 rumbly goodness.

As a side note, there was no 'weep' hole or any other factory leak in the exhaust system.


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At 34k miles they replaced.
22734961 Gasket 3.613
25814606 Muffler 3.701

It fixed the problem. However I will say at 79k miles now I am getting a slight whistle again.
alright so after reading all of these, it sounds like it is for sure an exhaust system problem, NOT a belt problem. However, my 07 g6 gt has just started whistling at mid to high rpm. the car has 83,000. heres the kicker, I have a magnaflow catback exhaust on it already and it never made any sort of whistle noise ever. So is it beyond my cat maby?

Cause before i read these posts, i thought it was ether serpentine belt, some other belt, or somting with my intake.
could be....

Just to be sure check the wear indicator on the tensioner to make sure the belt isn't at its limit.

When I first started tracking down the noise on mine the belt appeared to be past the half way mark on the tensioner so I replaced it.

Didn't fix jack but I felt better.

The Magnaflow kit replaces the muffler, resonator and pipe all the way to the exhaust flange at the back of the engine so if the new resonator is on there the exhaust probably isn't the source.


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Wear indicator on tensioner, new one for me. How about a pix.
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