Brake rotors get too hot

More than likely the lip seals on the calipers are plain worn out. They are designed to retract an incrementally amount to pull the caliper piston so as not to create friction of the pads onto the brake rotor. If this was a taxi - I would consider this car was under severe service and replace the calipers. As for the brake hoses...there really is not way to really check them (unless they are plugged within - basically the sheath inside has created a blockage - and you cut them open to investigate. Of course now that you cut them you get NEW ones.
Replacing both calipers and hoses should fix this problem. You can easily check just by looking at your rotors. They should never become bluish or polished as that means they have become very hot due to severe braking or defective operation in which the pads are not retracting from the rotor surface. Again, due to being a taxi there could be more issues as they come along and you discover them in time. And while we are at it..the most important part - Master Cylinder. Thats the heart of the system and if you consider how many times that has worked - unless it was replaced before - its probably worn as well.

 

Should be under the steering shaft,deep under.l To see it one must get on hands and knees. Also if you look intensely in Prius Gen 2 Maintain and troubleshooting there was a procedure by one of our Genius Techs for bleeding the brakes in a particular order. I believe you are going to have to replace all cylinders and lines. Your rotor also looked scored, if so, previous owners beat the hell out of that car. I would have them trued up as well, otherwise your pads will wear prematurely. There is no cheap way to overhaul brakes.

 

Have you looked at the caliper slide pins? They need to be inspected, cleaned, and lubed with a light film of high temp caliper grease.

DBCassidy

 

Good idea.

 

And then rotate your head 180 degrees, kinda like Linda Blair in The Exorcist. Either that, or lie with your back on the door threshold, and wiggle your way in, 'till your spine snaps. Nothin' to it.

Hopelessly off topic, Happy New Year.

 

Yep, it's a snap.



merged



Just an afterthought, you mentioned a part getting cherry red hot. Whatever it's rubbing against is also wearing at a much faster rate, deforming it, changing the tensile strength, scoring rotor more? Plus of course various safety issues.

I do like reading your posts tho.

 

^ Wow! All I got is good luck, hope it gets resolved.

 

Oh No no no.

A used or rebuilt is not recommended.

You see, the cylinder inside the MC will wear and most likely rust causing your system not to retract properly.

A rebuilt one will do fine for awhile but like the used one due to the cylinder wearing out the new seal will not last long as a new one.

This is a safety item, do not go cheap here. You don't have to get factory but a good aftermarket would be better then a used one. Remember, unless they kept the MC in fluid, it will rust inside.

Another note, for others considering doing this or any brake job for that matter.

Never force fluid to go back up to the MC, it will force contaminants and debris in there and may damage the MC. Instead, place a wood block, a 2x4 on the brake pedal depress 2 inches then open the bleeder valve then evenly compress the pistons followed by a bleed or flush.

Never ever depress the pedal to the floor, this will certainly kill your MC as going past a certain point of wear will damage the internal seals.

My 2 cents

 

Remember, you cannot bleed the brake system yourself. The dealer has the right machine and procedure for this, after bleeding the dealer should test drive it with you in passenger seat.. Sometimes one must bite the bullet and pay.
Good Luck.




Merged

2 cents worth, is well worth it. Good advice

 

I am just looking into rotors for my brake-eating minivan but the orig pictures on Post-1 seem to show the new rotors might be wider gap (which is what I am planning to get for my Minivan due to over heat). But for Prius I'd be shooting to match OEM rotors.

 

Sorry to agree, the MC is not cheap. If cost is an issue, I totally understand, that is why most of us are here to DIY, right :-/

I would then try to rebuild it, but most important thing is to follow proper factory procedures. I just finished reading the pad replacement and bleeding. Wow, very complicated and the factory uses a HandHeld diagnostic and tester tool to connect to your OBD2 to simulate manual bleeding procedures.

If you do get to the actual tear down of the MC, feel the cylinder's inner bore, you will feel a ridge or two, be very careful when cleaning this, if rusted, removing it will and most likely take metal with it that may cause a leak. Might want to consider taking it to a machine shop that can do precision cleaning with their dial and C&C machine???

As I was reading, I noticed they require you to disable the braking system by removing the relay/s to basically disable the actuator, once air gets in there, even Toyota states it is near impossible to bleed the air out. I think one can also just disconnect the NEGATIVE side battery to insure relay's do not kick in but then again procedure for bleeding requires the car to be turned to IG "on" so probably removing the relays is the only way.

Okay fellas, lesson learned here do not allow old fluid to go back up to the MC and never allow reservoir to go below MIN, this is where you need a helper to keep an eye on the fluid level.

 

Interesting reading about the brakes on the Prius,
Replacing the pads was the first thing I did myself on this car. It was either $600 for the dealer to do it or less than $100 to buy the pads from the dealer and put them in myself. I've must of done a couple hundred of brake jobs in my life so I figure what the heck. I must have had a guardian angel looking over me as Just popped the pads out depressed the pistons and inserted the pads. (Getting Genuine Toyota Pads were nice as they fit with no "adjustments"). The rears were a little different as I had to get a tool to screw the caliper back in.

I went to start the car and all the warning lights popped up, I turned it off and back on and the warnings went away.
I think I read later were the car will pressurize the brake system when you get in and fortunately I let the door open so it never pressurized the system.

However if bleeding is so complicated, I may leave it up to the dealer. I have a pressure bleeder that I use on all my other cars that makes quick work out of bleeding the brakes. But it doesn't sound that simple on this car.

 

Bleeding the lines at the wheel cylinders, anything you'd normally do in a brake job, is pretty much no sweat, as long as you keep the reservoir full and no air getting in.

It's when you let any air in the Rube Goldberg department up top, complexities arise....

-Chap

 

^^^ +1