New to Prius-unknown noise

Yes. Mine has done it since day one 8.5 years ago.

 

I can't remember exactly what it is but IIRC it is either something in the hybrid cooling system, or the brake regenerative system. You might find more info in the technical forum.

 

Sounds normal. My 04 does the same

 

Its the coolant heat recovery system. Every time you shut your Prius off (If its a North American Prius) it pumps the hot coolant from the engine into a thermos, where it stores it. The next time you start the Prius, it pumps the saved coolant into the engines coolant loop so you have less emissions from a long warm up period.

The pump will run 95% of the time you shut the car off or turn it on. Completely normal.

 

That's why you don't turn if off for short time wait.

 

Mine does it too, and it was so loud that I was worried. Brought it into the Prius specialists in SF (so you know they know what they are talking about, since every other car here is a Prius), who told me that it was the coolant pump, and that it was normal. They said I could replace the pump if I wanted, but advised not to waste my money. They said they had NEVER seen one break.

 

Like PriusGuy32 said, it does pump coolant and it is normal. For a "Prius Specialist" to say it is THE coolant pump, is normal, and then suggest you could replace it but advised not to waste your money, is a little on the gray side (not quite the dark side). It is absolutely totally normally operating to the advantage of the efficiency of the system and saving you money on gas. This is a fairly low tech way to increase the efficiency of what may be most high tech car on the road. It strikes me that for a mechanic to suggest he is looking out for you by saving you money on repairs, though there is nothing wrong, is disingenuous at best and setting you up for the next big trust issue at worse.

 

I should have clarified that the mechanic told me there were 3 or 4 pumps (I don't recall which), and explained the entire mechanism to me. But, since he has never seen one die, and other than being loud, it works fine, he did not recommend that I replace it.

 

Ok, that sounds better. My confidence in your mechanic is restored.

 

That's a normal noise and why my son calls the car a "spaceship"!

 

exactly, it does really sound like spacecraft from movies