Every time I open the drivers door, a whirring sound starts from under the hood, then it gradually slows and stops. Maybe from the inverter area. What is this and is it normal operation? Or is this the Prius saying hello?
That's the brake boost pump building up pressure and it is normal... After it does this if you sit around before taking off the pressure drops a bit and the brakes can feel a little grabby until the pressure rebuilds. Not a big thing though...
It *is* the car saying hello, and reassuring you that its braking system will work just fine despite everything you've heard on the news. . _H*
So what is the difference between this sound and the coolant bladder or coolant exchange tank or whatever it is? I had read on here previously that is what the sound was...
There is no more coolant thermos in the 3rd Gen Prius. It was in some way replaced by a coolant heat exchanger on the exhaust system.
ah... My lowly Gen II makes a different whirry sound then! So I wonder if I make both sounds, or if Toyota decided since they got rid of the source of the sound on the Gen III, they would add it back in with a new source, the brakes!
If you like the whiring sound: try staying in your car for a few minutes or returning to the garage after turning the car off. You practically get an orchestra performance.
The Gen II also has the electric brake accumulator pump, although it doesn't run when you open the driver's door. You can hear it about every third time or so when you press the brakes. Tom
I noticed this for the first time a few days ago. There was such a chorus of sounds I started to refasten my seat belt just in case! The Prius really is from outer space!
