Here's the deal; when I am under very light throttle or decelerating, I am getting a hiss from under the truck. Something like a tire losing air. It's not the whistle from the turbo (I know all about what that sounds like!! ;D). Anyone else having this phenomenon? It just started a few hundred miles ago, and everything seems to be running fine?

 

Have you checked the turbo intercooler line clamps? Thats what it sounds like to me. Just a thought...CC

 

Have not checked anything yet, just thought I would ask around a bit. I will get under the hood this weekend and check everything I can find that has a clamp mechanism. Thanks for the input!

 

TYZ
Is the truck still hissing?

Mines always sounded a little " airy " & even more so with the exhaust brake on. I thought it was normal.

 

I am not sure if this is the same problem, but after I had my '03 for a month I noticed a hissing sound, only when I gave it throttle. Come to find out, I had all four of my bolts loose on my intake to the motor. I was on my way home and had to pass the dealer so I stopped by and they tightened them up.

 

Hissing has progressed into a buzz, right about 1300 RPM, no matter what the driving conditions (i.e. accelerating, decelerating, loaded, unloaded, etc. etc. etc.). Only happens at full operating temp, though. If it's cold, it won't do it... :-