My 2016 Three Touring has recently developed the habit of squeaking (like the sound of an unlubricated bearing, or squeaky old brakes) when it's first driven for the day. It's a rhythmic squeak that follows the cadence of the tires' rotation so pretty sure something to do with the drivetrain. I haven't been able to isolate a location very well other than it seems to be towards the front of the vehicle. The squeak dies down after the first 400 feet or so of driving, and does not return - until the next cold start, and even then not always. It's occurred three times that I've noticed so far. It's got about 4900 miles on it. I get the feeling if I take it to the dealer they'll just say can't reproduce, since it'd be warm long before it arrived there. Any ideas what's going on or what I can check to make a better diagnosis?
Possibly rust on the rotors? Since the prius uses regenerative braking a lot, the rotors are more prone to get buildup than regular cars. Forcing the vehicle to do mechanical braking might clean off rust and other accumulations. Find an empty stretch of road, go up to 40+ mph, shift into N and brake to slow down. Rinse and repeat
Has it been rainy? How long has the car been sitting, ie: are you driving daily, or the car sits a day or two? Is the engine running? I'm just thinking, with 4th gen's greater propensity to run electric-only at start-up, little noises are more obvious. My guess too is the rotors are a bit rusty. I'd do nothing: the regular brakes do see enough use to clear them. As you say it clears up in about 400 feet. If you're not DIY, you're just about due for a dealership visit anyway? Doesn't hurt to mention to them, see what they say. They'll have the wheels off for rotation, and be doing "visual" brake inspection.
Would rusty rotors make noise when the brakes were not applied though? This occurs regardless of brakes being applied. It's being driven daily, and splits its time between being in the garage and outside. And thanks for your help. I've been a lurker for a long time and learned a lot from priuschat
Our rear brakes will make a slight high-pitched sound (akin to running a finger round a wine glass sound), just backing out of the garage, I think brakes applied or not. But just for the first few seconds, say till backed out onto the street. Not sure. Just for giggles take a look through the wheel openings with a good light, to see what the rotors look like, any rust or scoring.
