Just wanting to know what causes this sound when truck is first started. WE have a 05 & 03 which does this now & then. Today when my son started his 03 I was outside and saw white mist come from under drivers side motor when sound occured. Thanks

 

Does the mist only occur during a cold start up or also when the radiator is hot? I'm not sure but could the mist be from the water condensing in the radiator fins from humid Florida environment as the radiator cools down? The air noise could be from pulling the water vapor through the radiator as it acts as a restriction through the cooling fins giving you a bit of a whistling noise until all the fins are "purged" of any collect water vapor. I get the mist that you are speaking of after washing my pickup.

L8r,.......dogger

 

Is the AC on? Mine makes a sound when I first start it up and the AC is turned on.

 

Yeah the AC is always on when I start it up, and it only does it about every other day on a cold start.

 

mine does it as well every other time when ac is on. compressor kicking in or valve on ac opening?