Leaky Reservoir Cover

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69valiant21

69valiant21

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Anyone know any tricks to getting a good seal on these covers? Getting tired of seeing my paint ruined from brake fluid.

Reservoir.JPG
I am tempted to go to a Wilwood master cylinder with a screw type cover:
https://www.summitracing.com/parts/wil-260-8555/overview/
 
People say that often such leaks are due to air in the system. That causes a geyser of fluid to shoot up as you release the pedal, which is also a good diagnostic for air bubbles. Of course, it could also be from sloshing as you turn.
 
Normally, those masters don't have a machined sealing surface. It's hard for the gasket to seal on a rough cast finish. You can try to file it smooth or you can do what I did and put a light skim coat of rtv on the lip. Just enough to fill in the casting roughness. I also switched to dot 5 fluid. Make sure the wire is pushing down on the lid tight.
 
After filing the gasket surface flat and smooth, you can also remove the bail wire and bend it at the red circle on both sides so the wire will clamp the master cylinder lid more tightly.
MS.JPG
 
Too late for you, but for others buying parts, you can fit a later aluminum MC by using a 2-4 adapter plate ($30). Those MC's have a plastic reservoir that seals much better and has a low-level sensor you can wire to your warning lamp (parallel w/ e-brake switch, either shorts to gnd). Many here use one for a late 80's Dodge truck.

If fluid is leaking out, then moisture from the air can get in and be absorbed in glycol fluid to cause corrosion. Glycol fluid is also a great paint remover (one reason I use silicone). I went even further on my 65 Dart and used the entire booster-MC from an LH car on Dart brackets, so no adapter plate needed and very cheap (see avatar).
 
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