I now have 71,000 miles on my 2007.5 lmm and when I crank it up it has what I can best describe as a tinging noise. I don't hear it all the time. It doesn't do it all the time but I have noticed it just lately. Probably no big deal but I was just wondering if anyone else has heard their lmm making this noise. Like I said, only does sometimes at start up and then goes away soon thereafter.

Are you talking about the type writer ticking noise common on these?

No. It sounds like something is knocks around a minute and quits soon thereafter. It just started and only does it every so often. Did not hear it this morning. My old 2001 2500 HD gasser sounded like a diesel on cold mornings but after it warmed up it would always quit making a this same type of noise.

typewriter noise, its random and comes and goes without rhym or reason. Normally happens after a oil change but not always. loudest at the drivers inner fender when it occurs.
no other common occurrences for noise on the lmm.

Mine has an intermittent sound like you describe. It comes and goes since my fuel system mods. Never had an issue in 5k miles (keep in mind only 15k total). At first it concerned me but never found the source with a scope. There are a few TSBs regarding intermittent engine noise and GM says its because of normal deposits in bearing journals blah blah and its always been there, we just hear it more with the later quieter model engines. Sometimes paranoia gets the best of me.

it's the sound of the timer for the I.E.D. in your truck called the DPF.

kidding aside, I agree with kgt, it's most likely the notorious typewriter sound.

or...could be the electric typewriter that GM installed to record every mod you do on the motor. :eek:

I had a similar sound for a while then it went away. I crawled under the truck and the metal line going in front of the DPF was broke. What happens is the exhaust shakes and the line flexes back and forth which causes the noise. It can come and go but when mine went it was the line snapped and no longer made the noise.

I do now think it is the typewriter noise that everyone has talked about. I am not worried or concerned b/c it is only every so often and just started. I guess mine didn't start until later unlike other LMM's. I have a 7.3 that's so loud I would not be able to hear this noise if it were occurring. Since truck is so quiet I notice any changes in any noises that may occur. Thanks for the responses.