In Reply to: Master Cylinder Seals '90 535i posted by Jim on September 16, 1999 at 22:25:48:
My Girlfriend just got a 1990 535i that I am doing the same with. I haven't had to do anything with her brakes yet, as they are in great shape. However I'll be doing stainless steel lines and such shortly. One thing I found on my 1990 325i last month was a leak just as you described. It looked like the master cylander was on the way out. It turned out to be the rubber grommets that attatch the reservoiur to the cylander. They cost about a buck each and take only a few minutes to replace. I'm not sure if the 535i is the same but I would bet they are. To replace the grommets you can use a Turkey Baster to empty the reservoir (don't reuse the fluid). Pull the reservoir straight up off the grommets, install the new ones, and refill the tank. You'll find you probably won't have to rebleed the brakes either.
It made all the difference in pedal feel, plus no more lost fluid.