:screwy: I need HELP my bravada is acting up, when you start it up and start to move, it sounds like a tracter trailer taking off :uhoh: untill you hit 20 mph then it stops. What can it be??????????????????

My guess is the cooling fan ...mine also sounds like a jet taking off till about 20 mph then it stops .
If you shut off your truck and its hot ,the fan starts up with the truck.
No big deal....I dont think.
What temps does your truck run at?...pretty hot here shutting mine down around 200 -210 causing the fan to engauge upon start up.However If the truck is shut off and th temps arent over 200 the fan stays off.
CS