Strange Intermittent Sound from Newly Acquired Used Prius

The whirring sound after the system is switched off is quite normal (I can only speak from experience of my 2009 Gen II), the sound is of the coolant being pumped into the thermos flask (yes, there really is a Thermos, just in front of the front wheel, driver's side!) the coolant is stored there so that next time the engine is used, it warms up quicker (more efficient). As to the other noises, it all sounds pretty normal to me! Good luck!

Posted via the PriusChat mobile app.

 

The coolant system pump makes obvious noise only on cold start-up and after shut-down, not during the drive. Can you hear that sound in addition to the sound in the clip you can hear while driving, and does it sound different? On the clip it sounds almost like something shaking in a can. (No marimbas under the seat?)

Can you tell roughly where the noise is coming from? If it makes the noise routinely while the car is in Park, open the hood and see if you can tell if it's coming from the engine compartment.

One remote possibility could be the ABS, and that should definitely be checked out. Look at your brake fluid reservoir--it should be clear or like honey at the darkest.

How many miles?

 

I've only had my Prius for the past 2½ years, but I've found that getting used to all the noises and whirrs as it drives, it's almost like having a conversation with the car, IOW listening to what it has to say, it's like it's telling me all is OK (…or not! ) I recently had to be without my Prius for a couple of weeks (see other threads about failing combination-meter) during which the local Toyota Dealer let me use a loaner (2016 Camry) (at no charge) and although the brand, spanking-new Camry was very sweet and drove well, I missed the quiet glide of my Prius! Good luck with your Prius, you'll find like many of us here, you'll fall in love with it!!!

 

That is probably the brake vacuum assist pump. It provides vacuum for the brakes when the engine may not be running.
It sounds like a rattlesnake and comes on alot if you pump the brakes.

Get in the car and without starting it pump the brakes a few times. That will initiate that sound. If it repeatedly comes all the time like its cycling that's a blown abs brake unit and very expensive to replace.

 

Did you ever find the cause/solution?

my 2007 Prius just started this - every 15 seconds while accelerating, or coasting or idling. Even for a few minutes after I turn it off…

I was thinking maybe a water cooling pump as that always makes a similar sound after I turn my car off…

thanks!
Lynn

 

You can learn what the different sounds sound like.

I always think the brake accumulator pump sounds sort of like a rattlesnake. (To be honest, though, I've never heard an actual rattlesnake up close.)

But it's easy enough to familiarize yourself with the sound yourself. Sit in the car, turn it on, wait for it to be quiet, then just start repeatedly stepping on and releasing the brake pedal. Every few times you do that, you'll definitely hear a little rattlesnakey pump noise pumping the brakes back up.

Once you definitely know what that sounds like, you can easily say "yes, that's the same sound I'm hearing those other times" or "no, the sound those other times is something else."