Deep Hum Sound in cabin?

[Cliffee]

I started noticing a deep exaust hum while cruising at 55-60MPH on the highway. It seems when the engine is around 1700-1800rmp the most pronounced. After I exceed 60 mph it completely goes away. It's there at all speeds whenever the engine hits this rmp range. Typically not heard at slower speeds because the tranny shifts before the rpms hit 1700 range. Its loud enough that it can be felt and overwhelms the radio.
Anyone experience anything like this? Its an 05 Crew completely stock.

Thanks in advance!

C

[bobo]

I have been trying to get that Hummm sound in my cab for the past week. She keeps saying NO. Maybe I'll shower. That might work.

[MIKE MOG]

I HAD MY TRUCK OUT LAST WEEKEND AND I NOTICED THE SAME TYPE OF HUM. IT SOUNDS LIKE THE AIR BOX IS NOT HOOKED UP, I WHEN I GOT HOME I CHECKED IT TO MAKE SURE IT WAS CLAMPED TIGHT AND IT WAS. LET ME KNOW WHAT YOU FIND.
MIKE

[sluggerjoe]

I have an '05 crew D/A that does the exact same thing. I'd be interested to hear an explanation. Mine only has 1K miles on it. It is annoying enough that I am going to take it in to the dealer and see what they say.

[madmatt]

does this sound like your concern?

Full size trucks equipped with the 6.6L LLY engine may have an exhaust moan/drone/vibration concern at approximately 1700 RPMs.

If so bulletin PIT3457A probably applies to your vehicle. GM engineering is currently working on a fix although installing two exhaust dampers 5" forward of the cat. has had limited success in repairing this concern. The P/N for these is 10199232.

[sluggerjoe]

Yup, that is what it does. It is not so noticeable when going through the gears but it is downright annoying when going down the highway. Anywhere from 56 to 60 mph and it's loud.

Thanks, Matt.

[Cliffee]

Thanks for the replies. It sounds like they all do it. I will call my dealer and speak to them about it. If GM is working on a fix hopefully it will be done faster than the wonderful stearing rattle resolve!!

[sluggerjoe]

The dealer says they'll put the dampers on when I bring it in for the free 3000 mi oil change. I now have 1600 mi on it and the noise has diminished by about half.