Okay first time posting but need to see if anyone has advice or a solution. 2001 prius 195k on it. No codes relating to abs. No brake line leaks nor leaks at the wheels. Car bleeds off brakes at stoplights. I have diagnosed it as a bad master cylinder is that a correct diagnosis? That being said master cylinders for Gen 1s are discontinued and I dont see any aftermarket solutions. Does anyone know of a retro fit or should I do the "rebuild kit" that has a new piston seal and retainer (my worry there is a possible worn cylinder) or is my best bet to find one at a junkyard or a full blown parts car. Thanks in advance.
You talking about the part that pedal connects to ? I believe that's a somewhat normal hydraulic 3/4 bore type master cylinder. If so very rebuild able.. but usually leak downs are in accumulator.
How would I go about checking and or verifying which component is the issue? Rather than throw parts at it that are expensive and discontinued?
Can you give any more detail on exactly what happens at stoplights, and how you went about your diagnosis that it's the M/C? If you're right, you're in luck, in that gen 1 had an inexpensive M/C rebuild kit available, which later gens did not.
Well considering normal vehicles and i see that these are more complex now i may be incorrect. But at a red light if I hold steady distance aka stop then hold my foot in that position the car will slowly start to release until it will just start rolling forward. I can push and hold constant firm pressure down and it will slowly go do the floor. Maybe 20-30 seconds. If it release all i do is pump it and i will have the pedal back at normal position and restart the process. Is that enough for you to go on? Thank you in advance.
If it is the accumulator, you're looking at 1K for the part. Labor cost is heavy, too, since a bunch of stuff has to be removed under the hood to get to the thing.
The gen 1 accumulator is in a tricky place, over on the passenger side, but PriusChat member rlin78 years ago worked out a way of replacing it with a lot less removal of stuff.
So then when it bleeds down do you hear a pump pumping or you have to pup pedal to get pump to run n pump accumulator up?
I will go listen today but I have to pump the pedal. Another reason I thought master cylinder is it does it with the vehicle off also if that's any help. Thanks in advance.
Well, nothing you have written here sounds like the accumulator to me. I was just responding to a drive-by post about the accumulator that happened to show up in your thread.
Well I really appreciate you stopping. To me it was sound ing like a basic master cylinder but when I started doing research I realized I didnt know that much about the prius brake system in comparison to non hybrid vehicles so I figured I better ask people who know before I throw discontinued expensive parts at a 24 year old car that probably isn't worth fixing for a few grand. Thank you again for your input.
Usually if you pull pedal off master cylinder in car remove circlip that holds pushrod to master cylinder now look at the dimpled aluminum plunger do it look wet ???? This is wer most master cylinders leak sometimes fluid will drop on car level w pushrod.
Twould take a bit of time to loose enough to really see in res. I would think in my old Corollas the clutch and brake cylinders could bleed and it'd be a bit of time before you'd notice the lil blk pancake going down in res. the float thing
