Weeping Master Cylinder Cap

[Mike B.]

Brake fluid seems to weep out of the Master Cylinder cap on my '61. Even after a fresh flush and bleed, and when standing still, a small amount of fluid can be seen near the vent hole.

Could it be that it is the wrong cap? I note that Corvette Central shows two styles for late and early 1961. I have a late car with an early style cap. Are the later style plastic ones non-vented?

Or perhaps the cap is missing a baffle on the underside to deflect any fluid that may be sprayed upward when the petal is stroked. Is there a baffle on the older cast aluminum style caps?

As usual, any help or ideas are appreciated.

Thank you.

[Joe L.]

Re: Weeping Master Cylinder Cap

Mike-----

The cap used for most 1961s was a cast iron cap of GM PART #5455826 (not the same number as the CASTING number found on this cap). This cap had an integral baffle.

The cap used for late 1961 and 1962 is a plastic cap. I don't know how this cap is vented, but I presume that it is vented in some way. This cap can be used as a replacement for ALL 1953-E61 Corvettes although it's not "correct" for same. You could use this cap for normal driving and replace it for "show" purposes.

Also, the cast iron caps used for 53-E61 require a gasket. This gasket was originally of GM #80445 (yes, that's a REAL old 5 digit part number). It's discontinued but available in reproduction. I don't think that the plastic-style cap requires a gasket.