2008 intermittent grinding noise in front?

Sounds like the classic rotor rust issue to me.

If the brakes aren’t used frequently, they develop a layer of rust that has to be “burned off”.

You can always put your Prius in neutral from time to time and stop using the friction brakes and not regen braking .

That’ll lessen the number of times you hear the noise.

 

I've also had the inner wheel well liner come loose and rub a tire at certain speeds or wheel positions. Sounds just like a loud grinding noise.

 

who replaced the brakes?

 

They get surface rust on them.

Then when it gets removed, it makes noise.

Search around here and you’ll find many examples of this behavior asked about and commented on.

Good luck and keep us posted .

 

Noises in the suspension and brakes should be inspected properly. Most places do it for free so that they can potentially earn your business

 

no issue putting it in neutral under 30 mph. doesn't take much braking to get the rust off. mine comes off just backing out of the driveway, unless its been sitting a long time

 

Also, it's impossible to put it in reverse above 7 mph. It will beep and put it in neutral if you try. I have.

 

I live in overtly "damp most of the year" London, where an overnight deluge can turn the brake discs rusty - overnight. Even more so if "The Spaceship" is not used over the weekend.

The result of such rust formations on the discs is repetitive grinding noises which will sometimes manifest themselves as soon as you start moving.

As I live at the top of a hill (I've fondly dubbed "Cloudbase"), I tend to do emergency braking as I roll down the hill, in an attempt to dislodge the thinly coated rust formations.

Occasionally, even that doesn't work and I'm left with a repetitive "squeak.... squeak..... squeak..." noise which will usually resolve itself after a mile or two of continuous driving.

I note there is less of this during the brief hot London summers, and more of this phenomenon as it gets colder and arguably damper.

NUU_M3 ?

 

If your Prius lives outside it will quickly get rotor rust. Most cars do but the Prius really makes racket.
The crunching screeching will happen the first time in the am when you go the first brake.

If car is garaged it will be fine.

It’s a good thing to keep an eye on the front brake rotors. Once in a while look through the slots in the front mag wheel and look at the rotor surface.
Should look like extremely smooth steel. No pits no circular scratch lines.
No rust. Just smooth surface.