1990 convertible, 66k miles. Had a problem with the pressure switch on the master cylinder, leaking brake fluid through the switch, coming out of the electrical connector. This was a very minor leak, but was a bother. Brake system worked fine, no lights or issues. Picked up a used good switch and installed it. No leak, system works fine. Depending on usage the system leaks brake fluid past the switch and drips below the body where the switch is installed. This may take anywhere from 3 days to 3 weeks, depends on how much I drive it. When I pull the switch the “O” ring is usually swollen or deteriorated. I put a new ring on, no leaks for several days. I’ve tried several different kinds of “O” rings and it happens with all of them. I believe I’ve tried buna-n, viton, nitrile, EPDM, all leaked. I’m using Dot4 brake fluid and have been flushing the system every couple of years. Any suggestions would be appreciated.
Thanks
karl