Re: Brad's Master Cylinder

["Jay Mackro" <jmackro@domain.elided>]

Brad Meilink had asked:
>
>My 87 Spider is leaking brake fluid between the master cylinder and
booster.
>Is this a sign of a bad master cylinder or just a bad seal between the
>cylinder and the booster?


Brad:

You  definitely have a bad master cylinder.  There is a seal between the
cylinder and the booster, but it seals air, not fluid.  Because the cylinder
side of the booster is under vacuum, it is pretty common for the rear
seal in the m.c. to fail, allowing fluid in the cylinder to get sucked into
the booster.  Eventually, the level of fluid in the booster rises to the
point where it begins to leak at the cylinder-booster joint.

You can rebuild cylinders - replacing the m.c. rear seal will generally
fix this problem (of  course, while the m.c. is apart, you should replace
all the seals).  Be SURE to use a turkey baster or some such
specialized automotive tool to get as much of the brake fluid out
of the booster as you can.   But, expect your  booster to die at some
point down the road - the fluid will eventually destroy the diaphram.

Jay Mackro

------------------------------