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Brake fluid leak

2001 toyota camry 4 cyl 170k miles, Brake fluid leak between brake master cylinder and power booster, brakes work fine, no leakage inside car, new pads and discs six months ago low miles since then. Is the master cylinder bad or the power booster or both? Can I rebuild them or do I have to replace them?

Not an expert on this, but it sounds like the seal on the back of the master cylinder is leaking. If so, the master cylinder is not terribly hard to replace. It might be possible for you to rebuild the MC, but I wouldn’t do it myself because you’ll likely be in a world of hurt if you make a mistake while rebuilding and the master cylinder comes apart while braking. A new/rebuilt part should be under $100.

Yeah I’m hoping it is ONLY the seal that is the problem. Could it be possible that the mc is not bad and only have to replace the seal or should they be changed together? You make a very good point for not rebuilding the mc. I think I’ll just replace it if that’s required.
I’m still concerned about the power booster. Is it still good or trashed because of the leak? Fluid doesn’t leak from the pb does it?
Also I forgot to mention at one point I could hear the hissing sound from that area. It stopped after I topped off the brake fluid and hasn’t returned. The car still stops fine.
Thanks so much for your input.

So far as I know – and I am not an expert on this – there is no transfer of brake fluid between the power booster and the braking system. I don’t know much about power boosters because I’ve never had trouble with one, but I believe they are powered by engine vacuum. I think that there should be no brake fluid further “upstream” than the inside of the end of the master cylinder that bolts onto the booster.