While under boost (sometimes more than others), I will hear a hissing like sound. No, it is not the turbo spooling. It seemes to cut in and out when under load. It ranges from not noticeable to "whats wrong with my truck". There is no rythem or anything consistant about it.

I drive a 2001 DMAX/Allison with 58k, bought the truck with 43k and has done ever since. It does not affect driveability in any way. It has had some injector work and something with the turbo prior to my purchase.

Here is my Vin if it helps. 1GTHK2619-1E226188

I am a mechanic myself (not GM) and it seems to be in good shape otherwise, the sound is just a bit annoying at times.

Thank you!

leak in the intercooler/hoses?

leak in the intercooler/hoses?

I would say it's a simmilar sound to that but it comes and goes so much. Say in 10 seconds of acceleration you may hear it come in and out 5-6 times. It is hard to tell but it seems to be the left (roadside) of the engine bay.