Master Cylinder gasket leak

[Leecbr]

I have an unusual problem with a leak around the cap on my master cylinder. I removed it to add fluid, and now it wants to seep whenever I ride it. It does not leak when sitting. It only leaks when I take it out for a drive. It is only a small amount. I I checket the rubber seal under the cap.It looks good but it still leaks the same. Any ideas as to what would cause this? The fluid level is right, and it did not leak before.The fluid level is 1/4 empty from the top, leaving room for expansion etc.

Has this happened to anyone else.

[madmaxx]

I had something similiar on a remote reservoir and finally determine it was the bottom leaking not the cap. It was a plastic wilwood remote resvoir that used an o-ring to seal the bottom with a clamp. After screwing around for weeks, I disasseamlbed, put SEALALL on the o-ring and not a drop in two plus years.

[FWB]

mine did that too, the gasket had a slight amount of scale on it from the master. take the gasket out clean it really good. i also flat filed the top of the master to remove any scale on it also. stuff a rag in the reservoir so you don't get any debris in there.

good luck, fred

[Leecbr]

ok...great, thanks guys. I'll give it a try..

[michel schryer]

I have the same problem right now with the remote plastic wilwood reservoir leaking from the bottom. Clean it good,go for a drive and check around the cap first and go down to the split where the oring is. I took it out,cleaned the oring and i changed the golden clamp for a regular hose clamp and I will see what happens. I have three reservoir and only one is leaking,probably because of the clamp not doing the job. I will replace those plastic reservoir eventually for better ones,plastic look cheap.
Michel

Originally Posted by madmaxx

I had something similiar on a remote reservoir and finally determine it was the bottom leaking not the cap. It was a plastic wilwood remote resvoir that used an o-ring to seal the bottom with a clamp. After screwing around for weeks, I disasseamlbed, put SEALALL on the o-ring and not a drop in two plus years.

[mbeers6]

I am having the same problem with my cast iron double reservoir. I tried replacing the rubber gasket in the lid, but that didn't help. I did NOT try filing down the lip on the master cylinder though.

Please let me know if you figure out to solution to your problem.

Here is my post in the B&B forum
Brake Master Cylinder upgrade?

[Leecbr]

Mbeers, My master cylinder gasket leak was solved by taking a small amount out. Removing the gasket and wiping the lid and gasket seal.

My fluid level was about 1/4 below from full and was leaking..Much like your situation, dripping onto the ground after I drove. So when I took some more out it stopped seeping when I drove. There was some wetness on the top edge of the master cylinder but it evaporated over time.

I removed some of the fluid with a turkey baster..Yes you read correct....but it worked.