'07 LBZ Air Intake Roar

[JohnC]

Years ago a friend of mine asked me to look at her ford pu. Problem was lack of AC and hot running in town, fine on the highway. The fan clutch was shot. When I replaced it she complained of roaring on startup.

Get over it!

[killerbee]

mine does it too, I took it in for service a while ago, they said GM's stance is as long as it shuts off at normal op temp and turns on if it gets hotter, it's working OK, GM has no need or desire to replace it due to fluid settling during sitting. mine does it randomly now, sometimes in the morning, other times after sitting a few hours during the middle of the day, no rhyme or reason. sounds like a cessna taxiing for a takeoff when it turns on...

The viscous slip medium in the clutch is a form of silicone, it's flow from chamber to chamber is modulated by a temp sensitive spring.

If the vehicle has some heat buildup under hood when it is shut down, The spring heats up and permits fluid movement while it is sleeping.

The term usually associated with your annoyance (and mine) is morning sickness. After I added a few changes to the front end, I rarely ever have that happen any more.