IronMikeRed2008

I have a 2008 Silverado with the V-6. At about 1,200 miles it started to make a little vibration noise underneath, which increased with each mile. At 2,800 miles I took it in, and they said there is a factory service bulletin on it to put a piece of flex pipe in. So, they cut out about a 5 inch piece and put a replacement piece in. It was much better, but I still feel and hear vibration.

I took it back, they tell me it's normal. Bull -loney. I know it was vibration free when I bought it.

Any suggestions? I heard there are some kind of exhaust system dampeners.They actually have a GM part number. Anyone have any experience with them?

mattsblacktruck

does this happen when your just cruising along and the tranny shifts into od and the rpms drop off and it sounds like a rattle coming from the passenger floor board that is what my 08 does and couple of people at my work tahoes do they were told the same thing thats normal ive never bothered taking it in but just curious if what you are talking about is the same.

Pepi

Feel for ya. My SIL and myself both bought new 2008 with V6 and both of them vibrate at 1200 to 1500 RPMs. His and mine has done it from day one. I didn't notice it when I test drove it probably due to excitement. I'm taking mine in on my Xmas vacation and getting the Flex done. Service manager told me it will help but probably won't eliminate all of it. He said it is just the nature of the beast [] Oh well, I got the truck for half the sticker

Forgot to add that I found doing research on this that GM has known about the problem since 1999. DICKS

Pepi

You got it That's is it for sure.

IronMikeRed2008

UPDATE-

To answer the question posed after my post:

No, there is no vibration in the passenger's side floor board, and it does not happen when it shifts into OverDrive.

I had an appointment at the dealer this morning. I live in Wisconsin and it was about 4 degrees at 7 a.m. when I started out for the dealership. It was groaning and rumbling more noticeably now then it has been since one week ago Friday when they put the flex pipe in. What I mean is, the flex pipe took most of the problem away, but in the course of the last week, it was getting progressively worse, but no where near where it was before the flex pipe was installed.

So anyway, it is definately more noticeable when it is cold. I took the mechanic (different guy than last week) for a drive after it sat for 3 hours to cool back down. When I take off with a very light foot on the peddle, as soon as it upshifts, in every gear, it starts to rumble and vibrate. I can feel the vibrationin my *** sitting on the seat, and if I put my left elbow on the armrest, it is noticeable there as well. It is not noticeable anywhere else, like the floorboard, or the steering wheel. At about 1700 rpm, the rumble and vibration vanishes.

So anyway, the mechanic heard and felt it immediately. Nice that he didn't have a dead *** and could feel it. He told me he has dealt with this before, and sometimes the flex pipe solves it, and sometimes it doesnt. And when it doesn't they put hanger weights on it and then sometimes that helps it out, but it is never ever 100% solved. He gave me a copy of the service bulletin. It is #PIT3566c: Exhaust Moan or Vibration Supplement to 02-06-05-003G - keywords Pipe Resonance (March 20, 2008). There you have it.

Good for Silverados from 1999-2008. Yes....9 model years with the same fricken problem. Anyway, just as the mechanic told me, the instructions are to cut a chunk out, install the flex pipe, and see what the result is. Quote from the service bulletin follows...."If this does not completely eliminate the moan/vibration, it may also be necessary to install on or more damper weights P/N 101992232 to the exhaust pipe in the area above the rear axle.

And that is what the mechanic did. These weights look like a cylinder about 4 to 5 inches long and an inch in diameter, with a piece of flat stock attached to them. The mechanic used a standard tail pipe/muffler clamp to attach them to the pipe via the flat stock.

Result: It helped considerably. No more vibration and rumble with every upshift, but...I know when I am at 1,400 to 1,500 rpm in any gear because I can feel it in my ***. Maybe I'm just too sensitive of a guy, but I know it didn't do that for the first 1,000 miles.

That's all I've got for you for now. If anyone has a better experience, I sure would like to hear about it.

josephbeck1963

My son and I bought the Flex pipe section on Ebay and installed it yesterday. Obnoxious vibration is gone from the exhaust system. Look up Service Bulletin 02-06-05-003G and you will see a link for the part number and instructions on how to make the repair. We backed the truck up on ramps and cut a 9 inch section of exhaust pipe out before the muffler. We used an exhaust pipe cutting tool, similar to a pipe cutter, but with the chain link cutting wheels. This was the hardest part, but we had it out in about 30 min and installed the flex pipe over the cut ends of the exhaust pipe and clamped it. I wish I had done this a long time ago. Its so much better!