Found torn caliper piston boot when changing brakes

Was replacing the rear brakes on my Mom's 2010 Prius II and found a tiny tear in the piston dust boot on the driver side. The piston still moves freely. I was hoping the boot could be replaced without removing the piston but from reading the repair manual on the brakes it specifically says the boot must be placed on the piston before the piston is installed.

So now I'm debating on what to do. I can rebuild the caliper for almost nothing but I can't bleed the brakes because of the Prius' system. I would have to take it to the dealer afterwards and not sure about driving it there. Does anybody know if things could be damaged with air in the system?

I thought about just trying to some how patch it since it isn't a hole or anything, just a crack. I need to do more research if that is even possible.

Otherwise it has to go to the dealer, who will probably charge $3-400.

Side note, the brake pads are worn very weird. The top outer pad is worn to 1mm, but the bottom still has 3-4mm. The inner pads are even with 3-4mm left. This is on both sides. This is the first time the brakes have been touched on the car, it has 55k miles. The front brakes still have lots of life left.

 

I found the brake bleeding part of the repair manual posted here. There is a section on how to bleed the brakes manually without the fancy computer stuff. Looks like I will be rebuilding the caliper and bleeding the brakes myself.

I also found other people had their pads wear the same way. The consensus seems to be it is caused by the pad ears not moving freely.

 

The calipers have Tokico stamped in them. From the pics I saw of remans they all come with the parking brake mechanism so I'd guess the parking brake is integral.

There has been a 3-4mpg drop, but I figured that was due to the winter weather. I'm thinking what happened is the outer pads at some point didn't return correctly. Normally they are straight up and down like | |, but somehow they ended up like /|. I'm guessing once the outer pad got that tilt to it the top was dragging.

Anyway I ordered a rebuild kit, crush washers, and decided I might as well get a new caliper piston. Parts should be here in a few days.

 

I've used reman calipers before, but I have lots of time so I don't mind rebuilding it. Also the remans I have used before have always needed to be painted. They put some kind of shiny nice looking silver finish on them but they rust instantly when they get wet.

Are you trying to jinx me lol, hopefully there will be no errors. If it doesn't work out I will take it to the dealer.

 

The parts came in today. In case anybody does this in the future one kit comes with parts to do both rear calipers. Also comes with the crush washers for the brake line. The parts guy wasn't sure the kit came with the washers so I ordered one separately. Glad I didn't need it since it is $7.60 lol

 

Finally got around to doing this today. Was cold the last few days so I was trying to wait for a warmer day but there is no such thing in the forecast.

Since the OEM repair kit has the parts to do two calipers I decided there was nothing to lose in trying to just replace the boot without pulling the caliper/piston. If I ruined the boot I had another. I also looked more closely at the manual and saw there was no clip holding the boot in the caliper like the front brakes.

It worked and it was very easy to do. I just extended the piston out a little bit, cleaned the surrounding area very thoroughly, pulled the old boot off, lubed the new one and slid it on the piston, then used a flat screwdriver covered in electrical tape to push the boot between the caliper and the piston.

Most of the time was spent cleaning. You want to make sure that no dirt or anything gets in there while removing and putting the new boot on.

Now I have a bunch of parts left over that I didn't need to buy.