whooshing sound?

What exactly is the whooshing sound that I am hearing when I start up the 4runner? The closet thing that I can think of is that it sounds like one of those little toy cars that you press down and pull backwards until the spring is wound up and it starts clicking. If you lift the toy car off the floor, the wheels spin freely and make a whooshing sound very similar to what I am hearing in my engine compartment, but maybe not quite that loud. I know this is odd as hell, but any ideas would be appreciated. From my limited mechanical experience, it sounds like a pump of some sort engaging.

Thanks

It is your viscous-drive fan for the radiator.

Can I assume from your statement that this sound is normal? I love this site.

Yes, it's normal. Most rear-wheel drive vehicles make this noise since they have longitudinally-mounted engines and engine-driven (not electric) fans with viscous-coupled fans. It takes a few seconds for the coupling to reach its normal operating mode (which is disengaged when the engine is cold).

More and moe people are not used to rear-wheel drive vehicles any more.