Leaking brake fluid from reservoir cover

[carlsbadGN]

After depressurizing the accumulator ball with 10 applications of the brake pedal (ignition off), I noticed brake fluid leaking from the top of the master cylinder fluid reservoir. The leak was just under the cover lock tab on the inside corner of the assist reservoir (largest) closest to the firewall. Looks like about a tablespoon of fluid escaped.

Fluid level was about at the top of the reservoir on the big side and about ½ inch below top on the driver’s side. After removing some fluid and depressurizing the system a couple times, she still dribbled some fluid but not quite as much.

I carefully inspected the reservoir cover and diaphragm for damage and they looked fine. This is a very low mileage ’87 GN and I wouldn’t expect to have component failure yet. Is it normal to lose fluid when depressurizing the system or could this be indicative of other problems?

 

[Turbo6inKY]

Sounds to me like the resevoir was overfilled. When you depressurized the system, it simply overflowed.

The fill marks on the resevoir are for a depressurized system, so if somebody added fluid without pumping the pedal 10 time, it'll gush out from under the cap.

 

[carlsbadGN]

My first thought was that it was over filled. I removed enough fluid so it only filled about 2/3 of the big reservoir when it was depressurized. However, It still leaks out of that corner after stepping on the brake pedal 10 times.

Any other ideas besides replacing the cover and diaphragm?