Help!, New Prius owner car making sounds

[willsurg]

Hello everyone. First I have devoured as much of the info on this board as possible and think this is just a great community. Second I just bought my first Prius, 07 with pkg5. I traded in a mercedes Benz c32amg whic was a gas guzzler! I have put about 400 miles in the last week and just noticed two sounds which dont sound right and was hoping for some reassurance that it was normal. The sound is like a fan which has something stuck in it, however it is not very loud. It seems to come from the drivers side in the front and it comes and goes. I thought at one point it would come on when I was regenerative braking but that did not pan out, now I think it comes on when I am turning. I thought I could reproduce it when the engine went on while driving but that is not consistent either. The sound is driving me crazy when it goes on, only because its a new car. The other sound is that on a road which is uneven, there seems to be a lot of rattling behind the dashboard behind the stereo. Otherwise there is no rattling. I just want to know if others have this same problem as well so I dont waste my time in the dealership. Otherwise I luv my new car and have no regrets.

thanks in advance!

-will

[Bill Merchant]

Hi Will. Congratulations on your new Prius and welcome to PriusChat! Live long and post often!

i think both sounds are probably normal. The Prius makes a lot of sounds that a less advanced car doesn't make. Without hearing the sounds, it's a little hard to guess, but here are some clues.

When you start your car and when you shut down, fluid is transferred between the ICE (Internal Combustion Engine) and a "thermos bottle" located in the front left corner, just behind the bumper. When you start up, a small (noisy) electric pump takes the hot fluid from the thermos and puts it in the ICE to warm it up faster to keep down emissions. Conversely, when you shut down, hot fluid from the ICE is pumped into the thermos.

Another odd, ratchety, sound comes from the brake fluid pressure accumulator. When you step on the brake pedal, you're not mechanically pressing on the master brake cylinder like in earlier cars, you are telling the computer how fast you want to stop. Regenerative braking, turning forward motion into electricity to store in the HV (High Voltage) battery for later use, takes care of most of the stopping, but some pressure is needed for the mechanical brakes, used just before you stop. A little pump comes on every now and then to make sure brake fluid pressure for the mechanical brakes is available.

As for rattles, as you read the threads here you'll see some people have them and some don't. I don't usually have rattle, but like you, on worn concrete roads, I can get some terriffic buzzes and noise which disappears when the pavement changes. I personally think it must be harmonics of some sort.

Other noises you'll here: racing engine, ICE running fast to generate electricity for the motors; ICE running when it's warm and the battery display is green, burning off excess electric charge to protect the battery.

The Toyota engineers are a pretty smart lot, so any regular noises you hear with any frequency are probably normal. Just drive and enjoy! All those beeps and dings sounds are supposed to be there, but search and you can find out how to disable many of the warning noises.

[willsurg]

hey Bill, thanks so much for the quick reply! I just needed someone to tell me it was probably ok so that I did not drive myself crazy I like ur email address! (mac only nut here since the apple II)