brakes, bleeding, and more fun

[andrew]

The brakes on my '70 SIIA 88 recently grew spongy and I grew tired of double pumping at every stop sign.

I thought bleeding them might help, so did that: far to near, tube/jar, enlisted helper (pump brakes down/loosen bleed screw/fluid out/tighten screw/let brakes up; repeat incessantly), the usual drill. I of course kept the reservoir topped up during the process.

I got very little air from the rears (bubble or two, maybe) and same from left front. The right front only, though, is about as much air as fluid at times and seems to never bleed through to pure fluid. I went through 16 ounces or more like this, first feeling virtuous for getting all that air out but now of course realizing the problem is deeper than a bit of air in the system.

I should note too that there have been no leaks I've seen in the system. The reservoir remains full for months after sitting. No tell-tale brake fluid from any of the lines, which are 3 years or so old. Also,

Questions, besides the obvious one of what's going on: Why the right front only? Clearly, unless the system holds gallons of fluid (it of course does not) why so much air? Where is it being introduced if there are no signs of leakage? Can this signal something like seals in the master cylinder?

Any help and ideas are appreciated. Thanks in advance.

[fly cubs]

The brakes on my '70 SIIA 88 recently grew spongy and I grew tired of double pumping at every stop sign.

I thought bleeding them might help, so did that: far to near, tube/jar, enlisted helper (pump brakes down/loosen bleed screw/fluid out/tighten screw/let brakes up; repeat incessantly), the usual drill. I of course kept the reservoir topped up during the process.

I got very little air from the rears (bubble or two, maybe) and same from left front. The right front only, though, is about as much air as fluid at times and seems to never bleed through to pure fluid. I went through 16 ounces or more like this, first feeling virtuous for getting all that air out but now of course realizing the problem is deeper than a bit of air in the system.

I should note too that there have been no leaks I've seen in the system. The reservoir remains full for months after sitting. No tell-tale brake fluid from any of the lines, which are 3 years or so old. Also,

Questions, besides the obvious one of what's going on: Why the right front only? Clearly, unless the system holds gallons of fluid (it of course does not) why so much air? Where is it being introduced if there are no signs of leakage? Can this signal something like seals in the master cylinder?

Any help and ideas are appreciated. Thanks in advance.

I played this game for a few months after replacing all slave cylinders and the master. No signs of leaks, and no fluid loss. Drove me crazy. In the end it turned out to be a faulty new master cylinder. Replaced it, and all was solved. Also, I found the Motive Power bleeder to be a lifesaver when it comes to bleeding. Makes the process fast and easy for one person (my wife said it was money well spent...she was tired of pumping the brakes!)

[mearstrae]

Sounds like the master cylinder seals are bad. Time for a replacement or rebuild.

'99 Disco II
'95 R.R.C. Lwb (Gone...)
'76 Series III Hybrid 109
'70 Rover 3500S