I noticed my rear brakes were getting quite a bit hotter than the fronts. I took off the rear calipers and discovered one was stuck, driver's side rear so I replaced both. Now that side seems normal but the passenger side rear is hot enough to sizzle water while the other three are just warm.

I replaced the brake hoses at the corners and all the calipers, pads and rotors four years/40k miles ago. I didn't replace the two center rear hoses though.

I'm wondering if this is more likely to be the center hoses collapsing or the MC, booster accumulator assembly. There are no lights on the dash. Could the system be preventing the brake fluid from returning on one side only? And would there be a warning light if it's the MC?

I'll probably go ahead and replace the center hoses, as that's probably the last possible fix I'd want to do myself, but I was hoping to see if someone had some advice. Thanks in advance.

Are the calipers you bought new or remanufactured?
Did you lube the caliper pins?

Bad MC wouldn't affect just one caliper, replace the center hoses (hopefully the other hoses you replaced 4 years ago are still good) and if the problem is still there then you have a bad/stuck "new" caliper, or bad/dry pins that are hanging up the pads.

Thanks. The calipers were rebuilt, from Advance Auto. They moved easily on the slide pins. I didn't take the pins out as they were together with the bracket when I bought them. This is the first vehicle I've had with this type of braking system. I was accustomed to replacing front pads twice before having to do the rears, but the rears on this have worn twice as fast as the fronts.

It's normal for the rears to wear out before the fronts, it is speculated that it's because Toyota designed it so the rears engage first to minimize nosedive when braking.

The first thing I'd look at are the calipers and the possibility that they're hanging up. Why you say? Because parts store rebuilt / remanufactured parts are notorious for poor quality right out of the box. I can't begin to tell you how many I've seen problems with.

And the sliders are not the only thing that can cause a caliper to hang up. I actually had a "remanufactured" caliper from Advance a number of years ago that looked pretty good, but locked up right away. I pulled the piston out to find it almost totally corroded. Yea, they rebuilt that one.

There can be several problems with this type of caliper. First, was the core that they rebuilt an actual Toyota part or an aftermarket part? Second, what kind of parts did they use in the rebuild process? Most of the rebuilt ones use junk components. Third, what was the actual process that they used to rebuild them. The word "sketchy" comes to mind here.

I bought them from Advance Auto. I usually go through RockAuto but I didn't feel like waiting. Afterwards I looked at RockAuto and saw I could have gotten new ones for the same price I paid for rebuilt. Although I'm not sure what the quality would be for a $65 new caliper.

I had an issue with calipers sticking on my 1973 VW. The rubber brake hoses were deteriorating and it caused an issue like you're describing.

I don't know if that's the case here, but considering the age of the vehicle it probably wouldn't hurt to replace the rubber hoses.

Thanks. I did replace the outboard hoses four years ago, but I didn't do the two inboard rear hoses. They would be 16 years old now. I'll do that first and remove the sticking caliper; hard to believe it would go bad in two days and maybe 30 miles of use.

It may never have worked properly since it was reman'd.

I had the exact same issue on my right rear caliper of my 06 4runner I thought for sure it was a problem with the hose or master cylinder but it ended up being the cardone ultra rebuilt caliper it was just junk ,My guess it would be a caliper

I know this is old, but I forgot to post that the problem ended up being the master cylinder. It was an expensive fix. The shop found a used one so not as much as going to Toyota but still pricey.

I guess the lesson is to flush your brake fluid regularly. I bought this 2008 when it was 11 years old, with 109k miles. I doubt the brake fluid had been flushed on during that time.