Hello My car failed its MOT 6 months ago on the rear near side brake not working or little effort. I bleed the brake and this cured the problem. How ever there was a small amount of fluid near the seal at the rear wheel cylinder.
I was told this was okay if it was only slightly wet inside the seal. The problem is that 6 month on today the air is back in the brake system again. The same rear brake is weak or little effort. (The other 3 brakes are okay) it only this wheel. I have changed the brake cylinder and bleed the brakes. Is there any other reason why air gets into this brake only.
Marcus
Marcus, by your explanation it sounds to me like the remaining air in your brake line could have been there from before and working its way down from the brake shoe wearing a little, filling the open room in the wheel cylinder.
Check the flared connection at the wheel cylinder and check your line for a pinhole by inspecting the brake line from the rear wheel cylinder in question.
I would recommend bleeding the brake lines out completely on all four wheels. Start at the farthest wheel from the master cylinder and work your way closer to the master cylinder with each remaining wheel. Be sure to not let the master cylinder get too low as to let more air in the system.
Also try not to press your brake pedal down too far while pushing out the air/fluid when the bleeder valve is open. This can cause the rubber seals in the master cylinder to go into an area of the cylinder not ever used and damage the seals. So pressing half way down is safe.
Good Luck Marcus, Drive Safe….. Dave
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