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MG MGB Technical - Brake MC

My B sat up for several months. When I went to get it running there was some black residue at the bottom of the master cylinder but the fluid on top was clear though the level was low. The brake pedal went to the floor. Could the seals in the MC reservoir have dissolved? I've never seen this before.
Jim

Happens when the fluid gets old and is not used. I'd try to bleed it and see what happens. If you have DOT 3 brake fluid in there, I doubt your seals dissolved.
J Arthurs

Your black residue is almost certainly what was floating around in the fluid until you allowed it to stand still long enough to settle out. I suspect that it's more likely that you've got a leak somewhere which would explain both the low level and the pedal-to-floor experience. If your Master cylinder seals have gone you should find that your footwell has quite a bit of brake fluid in it(!) and pressing the pedal should have irrigated your right sock with the same substance. If not, I'd whip the rear drums off and inspect the rear wheel cylinders. It's amazing how bad these can get without your noticing the gradual degradation in rear braking efficiency (alright, wihout *my* noticing the gradual....). If they were marginal, laying up for a bit has a habit of finishing them off.
Tim Cuthill

This thread was discussed on 02/07/2002

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.