High Pitch Squeal

waterfowler76 said:

i'm prety sure Jetmech had the same problem and found he had a small hole in his flex pipe and he fixed it. Maybe he'll see this post and chime in. I'll see if I could find his post.

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First off, hi, just joined the site tonight. I’ve had my 07 convertible for 2 weeks, purchased as certified used, 34,000 miles. I have mine in the shop right now for this same problem. Service guy says it’s the exhaust, something related to a small hole he said that causes a whistle. He also told me that he’s got a service bulletin from GM acknowledging it but it says not to fix it. I’m in the process of going through the service manager and then I’ll go to the owner if necessary. I knew the car had this squeal when I test drove it, mentioned it to them and they said no problem they would fix it when I brought the car back for a seat belt guide that was broken. I’ll get to the bottom of it one way or another or I’ll tell them to take the car back. There is absolutely no way I or anyone else in my opinion would buy a car knowing it had this squeal and could not be fixed. I think I remember reading on Edmunds that other have had to have the exhaust changed by the dealer to fix it.

Art.

Mine was definitely the exhaust. After some arguing with the dealer and threatening to return the car because it was written down when I purchased the car that the “squeal” had to be fixed, they replaced the exhaust. I read the GM tech bulletin and it’s complete BS, says the weep hole is functioning as designed and the exhaust should not be replaced. Many early G6 owners said that replacing the exhaust fixed the problem but that it reoccurred within 8K-10K miles. I’m currently at 12,000 miles on the new exhaust and still no whistle. Maybe they replaced it with an after market exhaust that either has no weep hole or it’s in a different place on the pipe.

Had they not replaced the exhaust I wasn’t actually going to return the car. Some said they welded or pop riveted the weep hole but then you lose the ability of the exhaust to drain condensation and it rots from the inside out. If the weep hole is the culprit then I personally think you could tune it out or at least change the tone. I personally believe the exhaust flowing across the hole acts the way sound is produced in a flute. I think either changing the size of the hole slightly (bigger or smaller) or the angle the exhaust hits the hole would change the tone or eliminate the sound all together. I was going to try this myself if they were not going to swap out the exhaust. I think if you were to put a strong pick or pinch into the hole and bend it to one side should change the angle the exhaust flows across the hole and change the tone. You may need to tap with a punch on either side of the weep hole if you can’t actually bend the metal. Another thought is to screw a small slide hammer into the hole and pull it out a little creating a dimple in the pipe. I don’t know if you should have the exhaust hit the hole head on or from the backside, you’d have to experiment. Personally I would try head-on first so the exhasut flows out of the hole instead of over it. I climb a 6% 2 mile-long grade on my way to work and that sound drove me nuts, people in the car next to me would stare because of the noise.

If someone tries my idea and it works please let me know. I’m crossing my fingers that my whistle doesn’t return.

Art.