Crashcrippleton
 

2003 GMC 2500 HD 4x4 Crew Cab Duramax LB7 with Super Chip programmer

Need info please.

Truck has 165.000 trouble free miles. Replaced the alternator and put in two new batteries. Have owned it for about 9 years. Bought used from a close friend.

In the last three weeks, have noticed a slight low-whistling noise (almost like a wind noise).
At first I thought that it was a tranny noise until one day going downhill, I shifted into neutral and found no noise. However, when revving the engine the noise increases and decreases accordingly. Thought that it might be the alternator (bearing) or possibly diode. Disconnected the alternator. Noise is still there. Everything else seems to be normal (gauges etc); no variance in power or performance. Anyone got any ideas?

That is indeed great..that number of miles trouble free, that is a great achievement.