Leaky wheel cylinder

[19_again]

Well I got my parts from that Autoist guy, rebuilt the master cylinder. Everything seemed fine, bled the system, took it for a ride and after a few good pumps on the brakes I had none! Got it back to home base, that was interesting, and found the right rear tire inbound side covered with brake fluid. Had my trusty wife partner pump the brakes while I watched and it appears as if the piston boot is stuck to the piston, because as the piston pushes out against the shoe, the fluid comes pouring out of the point where the boot meets either the seal or the cylinder housing.It's almost as if the boot were being pulled away from the cylinder as the piston comes out? Any ideas? It appears to be a newer cylinder and the boots look quite good, the pistons are still shiny. Oh Yeah, '66 MGB

 

[tony barnhill]

Don't even waste time with it - just replace the cylinder...they're cheap enough.

 

[19_again]

NOw that you say that, I looked at the Moss book to start to put another order together and realized that the bleed nipple is part of the master cylinder "assembly". The DPO had already replaced this cylinder that's why the piston and boots look so good and why there's a new nipple also. Could there be something that's causing this cylinder to fail repeatedly? I'll PM you an order Tony.

 

[DrEntropy]

Yep! Go to NAPA before they close and I bet there's TWO of 'em on the shelf!

...that's a hint you need to do the other side at the same time, BTW. /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif

 

[DrEntropy]

Wiataminnit!

Drums off, clean and assemble all as it should be with the adjuster backed out. Drums back on and adjust the shoes in until you can feel ~slight~ resistance while rotating the drum. Pull the E-brake a few times (this "centers" the shoes) and repeat the mechanical adjustment. THEN bleed the system. Sounds like the shoes were maladjusted and allowed the wheel cylinder piston to travel past the outer edge of the bore on one side. If this is NOT the case, and the cylinders look "new" they may have sat in one position long enough to accumulate some rust in the bore and that abraded the seal causing failure. A good visual inspect of the offending cylinder bore would tell quickly.

 

[19_again]

Too late, I'm already drivin' down the road to NAPA. HEHEHAHA
But really, I was planning on tackling the handbrake, which doesn't work at all, after I had the pedal brakes squared away. One cylinder is old one is new, and it's the new one that has failed. That;s why I'm curious about a cause for successive failures. But I think your idea of the improper prior adjustment is a likely situation.

 

[DrEntropy]

meh. This is the ONLY forum where members seem to post as quickly as a problem arises... sometimes with some confusing results!

Keep us informed as to what ya find!

 

[19_again]

Tony, I try to give you all the business I can as a supporting vendor as well as the great info you bring, but in the case of the wheel cylinders if I can go to a good parts store and pick them up in the morning I can be back in the saddle right away. Are these just generic items or are they somehow special?
Mike

 

[tony barnhill]

No problem with doing just that - lots of small stuff can be picked up locally (points, distributor caps, etc)...not sure about wheel cylinders though