just bought Prius month ago, making sounds when brake

It's common to hear a "very quiet" noise. The dealership may have replaced the pads and the pads are brand new wearing in. It gets louder after the car sits for a few days in some humidity.

Welcome to PC!

Pixel XL ?

 

congrats and welcome!

yes, you are being paranoid. prius rotors rust because regen braking allows the pads to spend less time helping than a regular car.

many owners get taken by unscrupulous dealerships who use the rust as an excuse to sell them unnecessary brake work. prius brakes generally last well over 100,000 miles, if cared for properly.

some climates are more conducive to rusting than others. for instance, when i leave my car in the garage overnight after it has rained, they are quite noisy the next morning.

try getting up to 30mph on a quiet road, and put it in neutral. this disengages the regen braking. slowly apply the brakes, and see if the noise dissipates after awhile.
also, regen doesn't work in reverse, or under 6mph, so that is sometimes enough to clean the surface rust.

all the best!

 

You can get the rust off quickly from the rotors by going downhill from an overpass, hill or exiting a freeway on neutral and press down on brake pedal.

 

"Reputable dealerships" typically have a 30, 60 or 90 day warranty so narrow down the issue so you can figure out what it is and they can repair it without charge.

 

get your smart phone and take a good clear picture of the front rotors through the gap in the mag wheel spoke. Post them here.

if you park your car outside the creaking will happen all the time when you first stop. Knowing how cheap dealers are on used resale they probably just sanded down the rotors. Take a look and see. If its a CPO I would take it back and get new rotors if there scarred and grooved.

Brake noise is a real issue on a prius. You can buy fabric wheel covers on ebay and amazon real cheap. Just throw them on. $25 for 4. It will help keep the moisture off the wheels/rotors.

 

Feel all the wheels after an extended drive, see if any feel exceptionally hot.

Note: the US maintenance schedule specifies a full brake inspection (not just cursory visual look-over), every 30K miles or 3 years. This is the wording, from page 41 of the Warranty and Maintenance Guide (you can download pdf from Toyota tech info):




This stuff is DIY'able, watch @NutzAboutBolts videos, pinned in the 3rd gen maintenance sub-forum. Also consider a tri-yearly brake fluid change. @NutzAboutBolts has a video on this as well. This is recommended by Toyota Canada now. Honda Canada has always recommended this.

If you DIY your brakes, I'd strongly recommend to:

1. Disconnect 12 volt battery neg cable at the outset.
2. After everything is reassembled, pump the brake pedal multiple times. Do not apply parking brake.
3. Reconnect 12 volt battery neg cable.
5. Do a short test drive, being very easy on the brakes.
6. Apply and release the parking brake several times. Raise the rear (front wheels chocked), and verify rear wheels are turning semi-freely, will spin a revolution or two with a push.

Special note: pay close attention to the rear caliper piston orientation, as shown in the attachement. It's imperative to get have the piston oriented thus, and well seated.

Lubes, these are non-kosher, but work for me:

Caliper pins, and their boots: Sil-Glyde Brake Lubricant
Contact points between pads and shims and caliper: Permatex Anti-Seize (or other whatever brand). Apply a thin, uniform coat.

 

This is absolutely normal and has happened with every Prius model and generation ever, and the "just occasionally" generally works out to "whenever the car has been sitting some hours in damp conditions."

And what you do about it is absolutely simple. You stop the car a few times, in neutral, and the surface rust gets wiped off and the sound goes away.

You don't have to make any big production out of it. You don't have to be going downhill, or hit a certain speed, or anything. If there's a stop sign at the end of your street, shift to neutral half a block early and come to a normal stop. Once or twice more at the next couple intersections if you still hear the sound. That's absolutely all there is to it. You will notice it again the next time the car has sat in the damp for a while, and you'll handle it the same way. After having the car a while, you'll almost get to where you don't notice yourself doing this.

Taking it to the dealer or a shop for this is nothing but daring them to sell you unnecessary brake work. And even some of the advice in this thread is waay overthinking this simple, well-known Prius quirk.

Now, because you did buy the car used, maybe you would do well to follow Mendel's suggestion and feel the rotors after a short drive to see if any is hot. That would let you know if there's anything actually wrong with your brakes, or reassure you that there isn't. Won't have anything one way or the other to do with the normal noisy-after-damp behavior, but it can give you peace of mind about whether there's any other concern.

For a feel-the-rotors test, you need to know that the rotors will naturally feel warm at the end of a driving test if you used the brakes at all to stop. So the most useful way to do that test is to plan out your short drive to end in a safe place with room to stop without braking. (I slow down as far as possible in B, shift to R at 3 or 4 MPH, then stab the brake at the instant between moving forward and backward. That doesn't heat the wheels because there's no kinetic energy at that point.)

If you follow that protocol, Prius brakes in good shape will have rotors absolutely stone cold to the touch.

-Chap

 

never hurts to have an expert look see.