My dad has an '03 quad long box with the Cummins and auto and whenever it shifts to overdrive lockup at 80km/hr (50mph) it goes chuchuchuchu, turbo fart, very noticable, every time. Unless you have your foot in it a fair bit it wont do it. I just dont think it should do it all the time. He said he hadnt ever noticed it until latetly, and its starting to do it more now. Only on that one shift to OD lockup. Any ideas?

Matt

 

It's called turbo bark, haha. Check for shaft play by letting the truck cool, and removing the intake elbow at the turbo, inspect the blades, and wiggle the turbo up/down left/right and in/out. Is there alot of play?