My '02 Duramax with 63,000 miles has recently begun to make a noise which is similiar, but louder, than the pilot injection noise. It happens around 1600 - 2000 rpm as it is shifting and runs rough while it makes the noise. It has only done this 4 times in the past 6 weeks, and only while the truck is cold. Runs great ,no fuel in oil, idles perfect, mpg hasn't changed. Any ideas. Thanks, Mike

hey I think I know what kind of problem your talking about..... its called piston rattle/slop in side the cyclinder.

I also have an 02 chevy duramax 4x4 2500HD and i have 73,000 mi. and i have noticed the same thing. GM told me not to worry about it just let it warm up wile you are driving to around 175 on your temp. gauge before you get on it hard. because your aluminum pistons have to expand to meet the cyclinder wall.

Thanks dirty, any techs have an opinion/suggestion ??

Bump, Eric(s) ???? Thanks