A couple on months ago I installed a new master cylinder and reservoir on a 230SL to fix a sinking pedal problem. The car showed signs of a long-term brake fluid leak on the booster and frame under the master. For a couple of months all was well, now it is back with a leak.
This is the master/reservoir arrangement where the front chamber has the internal hollow bolt to hold it in place and an o-ring to seal it. The rear has one of the regular bushings. Both were renewed when the new parts were installed.
The leak is coming from the rear seal. It only occurs if the car is driven. I can clean it off and the car will sit with no leaking.
Last evening, I pumped the pedal and watched the reservoir. Fluid is being pumped into the rear chamber of the reservoir when the brakes are applied. My theory is that this is creating pressure and that the seal is designed to seal the reservoir/cylinder against, but doesn't work against pressure.
Again, from the appearance, this has been going on for a long time.
Other ideas, suggested fix?
Cheers,
