Rattling noise under acceleration

[txguppy]

I know the ticking noise has been talked to death. But, the noise I have heard for a while now is under hard acceleration. It sounds like "valve rattle" in a gasser. It quits after upshift and begins again before upshift. It does this intermittently. Also, for the first time, yesterday I was pushing her hard getting around some oil field equip. and noticed the rattling sound again around 90mph. I could actually turn the sound "on and off" by feathering the go pedal. What is this noise?

Thanks,
txguppy

[NWDmax]

Txguppy: Sounds like the pilot injection is cutting in and out. I get the same thing in my truck and usually happens as the truck defuels between shifts and when the engine is not fully warm. There are times that it does it at part throttle too. I consider it to be a normal part of the Duramax's character and don't feel it hurts anything. Do a search under "pilot injection" and you'll find more info on same. smile.gif

[txguppy]

Thanx, NW, I know I'd read about it before, just could'nt remember what caused it.

[esmo77]

I have posted on this subject in the past. As coincidental as it may be, I recently added a Flowmaster muffler # 53553 and started using Rotella fuel additive and have not heard this sound since, 1 tank of fuel roughly 425 miles. If your are not using an additive may be it would help. I am glad mine stopped doing it because it was starting to concern me.

[RapidMax]

esmo:

how do you like that muffler. i'm looking for some more diesel sound and better flow -- but don't want to go nuts spending the money on a full exhaust.

[esmo77]

Rapid I really like the tone, better flow and it gives a little quicker throttle response. It is a nice fit just cut and weld. Esmo