We've had our Prius for a little over a year. It started squealing about 4 months ago. It happens when we turn off the car. It gets rather loud at times. We've taken it to the dealer and they said they couldn't get it to do it. Now it is really loud and consistent. We've even recorded it. (The dealer just seems to humor us when we tell them about it.) Does anyone else have this noise? I know what it's supposed to sound like, ours is like a "stuck pig"...it really squeals! It doesn't have that nice hmmm like it used to.
If it occurs before and after you turn on and off the car, its the coolant transfer pump. Note: the pump usually turns on if the coolant in the thermos is hotter then the coolant in the engine.
The coolant transfer pump gets much noisier in cold weather, but noise is not a failure. You may want to complain about the coolant transfer pump noise to the dealer and have them note your complaint in their records. There have been a few failures after 36,000 miles, so documenting the noise may help get a warranty replacement if it really dies. Watch out if your Prius stops making the noise, the pump may have stopped functioning. This is not a safety issue, since the car will run fine without the thermos bottle of hot coolant. It is an emissions issue since the hot coolant gets the ICE warm faster.
Mine (2007, just under 27,000 miles) has the same issue. I took it in last month and the dealer replaced some part of the pump system, but it didn't help. I'm living with it for now, but will bring it up again at the 30,000 mile service.
I often hear my Prius coolant pump come on after I park. It's like a soft prrrrr sound. Anyhoo, IF the pump fails does it pop a code into the diagnostic computer so the techies at Toyota can pick it up or do they die quietly? OOPS Found the answer: http://priuschat.com/forums/prius-t...ant-heat-storage-thermos-how-do-you-test.html
My Prius also makes noise when I turn it off. Mine sounds like either a goat or a sheep bleeting noise. It does not do it everytime I put it in the garage, but very frequently. I am glad to hear that I am not crazy in hearing this. I don't know if it is worth mentioning to the dealer or not.
