Looking for a second opinion on our 2001 Prius. We bought it new, have had it serviced regularly, and have all records. It has 236,851 miles, all in and around Berkeley, California. It has never been in an accident other than minor dents and scrapes. The following parts were replaced recently: new catalytic converter Mar. 2024 at 234,990 new 12-volt battery Dec. 2023 at 234,841 new main battery Feb. 2023 at 233,558 No other major parts have needed to be replaced to date. The insurance company declared it a total loss when the catalytic converter was stolen. To re-register it we had to pass a brake and light safety check. After some repairs to the lights, that and a smog check were done in November. The car is now making an odd noise when the brake pedal is released. Our shop says that's coming from the brake master cylinder because the brake booster is failing internally and to fix it they'd need to replace the booster before being able to tell if the master cylinder needs to be replaced. They say the master cylinder is no longer being produced. We like the car and would prefer to keep it if possible rather than buying another even though at this point it probably doesn't make much sense economically. If a new old stock or low-mileage used master cylinder is available maybe we could replace the whole thing at once. Or maybe since moving parts are starting to wear out we should sell it as a parts / project car.
You probably need the big electrical part of the brake system similar to Gen2. Not the part connected to pedal. The part with all brake lines and the accumulator and pump .right behind the hybrid synergy drive unit or inverter. The master is pretty rare . And is probably buildable w new seals of twas needed. Like most. I would think anyway.
You're kind of all in now It would seem silly not to fix it basically with everything else that's gone on most of that stuff can't move to another Prius unless it's of the same year and type so you might as well keep her going.
The brake booster/accumulator R&R was a $3K job at my dealer's. Cheaper than a new car or certainly even a decent used one, and we love the car. If you got 233K+ miles out of your original HV battery, ya done real good. I'm on my third replacement (the first replacement was faulty, and the second didn't last as long as it should have: beware Dorman!). The third one is a "newer generation cells" version from GreenTec. I'm expecting it to last the life of the car/me, whichever comes last. Also had to replace the exhaust line, including cat, because of that dopey flapper valve that gets rusted up. I presently have a lawn and garden tractor 12V battery installed and it's giving good service; no need to spend big buck$ on today's expensive 12V. Good luck with whatever you decide!
If you do end up needing a master cylinder, contact member ronlewis. See this thread: Anyone need parts? | PriusChat
I wonder if those things are rebuildable like the old master cylinders and all of our old Toyotas they were stamped 3/4 or 7/8 or whatever and took a seal set of the proper dimensions mentioned above fit the rubbers the right way clean the boar maybe hone it and put it back together and off you went.
The gen 1 brake gizmos are pretty spread around in the engine compartment: The "brake booster (master cylinder portion)" is where you expect a master cylinder to be, on the firewall lined up with the brake pedal, looks a lot like a master cylinder. The "actuator" (with lots of brake lines connected) is more amidships on the firewall, big square thing, and the "brake booster (power supply portion)"—what we'd later call the pump and accumulator—over at the other end of the firewall. The brake ECU is in the dash. There's also a front/rear proportioning valve—not shown in this picture—down low about where you expect a proportioning valve to be. That's a plain old hydraulic proportioning valve like other cars had. There is a part number for a rebuild rubber kit for the master cylinder portion.
Is this a common problem on the gen 1's? Does replacing the brake fluid regularly help to lower chances of failure?
The rebuild kit for the master cylinder looks to still be a thing, though: 0449347010 - Google Search
