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Deansel
09-07-2005, 19:09
Hi everybody, I'm a new Duramax owner and I have a question concerning a low-pitch noise or a loud humming sound. The truck is an '05 GMC 2500 CC and has about 3000 miles on it and makes the noise at highway speeds of 57 to 59 mph, RPM's at about 1750. It seems to be coming from under and behind the cab. Top suspect is the exhaust.

Anyone else have this noise or care to guess the cause?

Great Forum
Thanks in advance!
Crusher2
09-22-2005, 17:56
Yup, I have the exact same problem. Research on another site suggested it was being caused by harmonic resonance from the exhaust pipe. The dealer in that case installed a couple of dampeners welded to a muffler clamp onto the pipe just before the Cat. I took mine into my dealer yesterday and had the same thing done.....it's better but the whine is still there. I'll go back to the dealer tomorrow and see what else they can do.
Also, GM has issued gm service bulletin 05-06-05-002 which apparently calls for the cat/muffler and pipes to be replaced to solve this problem. My dealer didn't want to do that, but if they don't find a way to fix it, we're going to have some bad words!
sluggerjoe
09-22-2005, 19:02
My 05 does it too. I've understand it is a common problem. The dampeners the dealer put on helped but the noise is still there. I have noticed it has gotten quieter with more miles. It was very annoying when new, now you can hear it but you have to almost listen for it.
Kennedy
09-23-2005, 03:33
I haven't noticed it, but then again my exhaust has been upgraded...
markrinker
09-23-2005, 05:01
I can't hear a @#$% thing - my '05 probably does it, but I would be the last to know.
SLT556
09-26-2005, 18:13
The solution to this was posted, with pictures for the fix, on the***********.com. Long story short, a vibration dampener (just a weight) was added to the head pipe.

http://www.the***********.com/forum/showthread.php?t=24776


Thought that might happen to the link.

www.t_h_e_d_e_i_s_e_l_p_l_a_c_e.comforum/showthread.php?t=24776 (http://www.t_h_e_d_e_i_s_e_l_p_l_a_c_e.comforum/showthread.php?t=24776)
Deansel
01-08-2006, 11:23
Dealer has ordered new CAT and muffler as per TSB for Crew Cabs and they should be installed within the next week or two. I will report back on the results.