I just started to notice a hum/hissing sound whenI start my truck. It goes away after it warms up, but I am concerned and wonder what it could be. No lights come on, all fliuds have been changed, and i have done a visual inspection as well and all looks good. Let me know if you anything simliar happen to you and the problem was. Thanks

 

Have you been running the defroster/defogger lately?

 

Is is something you hear inside the truck or outside?

 

I hear on the inside or on the outsideof the truck, but it sounds like its coming from the engine compartment. It's not the defroster or fogger.

 

Could be the air intake. Have youchecked your air filter and cleaned your throttle body?

 

The reason I asked about the de-ice is that it uses the A/C ... and the compressor can start to make odd noises when it's on it's way south.

 

I had a hissing noise and it was a $2 gasket between the air filter case and the intake top. It is called Air Cleaner Mounting Gasket and you can get it at autozone if this is your problem. It used to come on when I step on the gas. Good luck.

 

Yep.....I gurantee its the air filte gasket.

 

Thanks guys i'll let you know what the problem was.