Unusual Engine Noise???

[DIESELMAX403]

I am experiencing what I think is an unusual engine noise with my Duramax. Near the top end of 2nd and 3rd gear under moderate to aggressive acceleration my engine noise changes from the normal Duramax sound to a hard diesel noise (sounds like an old Cummins). Once it shifts gears and the engine rpm drops it goes away. Sometimes its very noticeable and other times it not. After talking with the dealership, they said it could be an injector problem. They also said it could be water in the fuel, but I just changed the filter at 10K miles and I always fill up at respectable fuel stations.

Has anyone experienced this and if so, can you give me some advise? I would like to diagnose the problem before I take it into the dealer for repairs if needed.


Thanks,

Dieselmax403

[mdadgar]

It's probably the pilot injection turning off at 2500 rpm or so.

Totally normal.

- Mark

[Duramaxdiesel]

Mine does the same thing. Don't worry about it. It usually happens when Steppenwolfs' Born to be Wild comes on and I floor it :D

[Murray the Cop]

It's the pilot injection. Don't worry about it.

[Jorday]

Same noise here on my new truck. I wasn't sure of the cause, either.

[Modified]

See link below describing Pilot Injection:
http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=3;t=005485

The other noise noticed under load, or in warm climates is the "Jet Engine Sound", which is the engine fan clutch engaging, which can get quite loud.