Master cylinder gasket

I wanted to check my brake fluid level in the master cylinder because one of the fitting was weeping. When I unscrewed the cap the gasket destroyed itself. Ugh! I've tried Walch's but they don't have any. Anyone have some suggestions as to where I can get another? It is a single reservoir unit on a 57.
Thanks

 

might be time to get a rebuilt master cyl. if you don't know the condition. Cheap insurance.

 

Thanks for the reply. That is a good suggest but the master cylinder is just a year old. It is in a FC-150 under the dash and difficult to R & R. Some one suggested an "o" ring and I've got one that will fit but will it stand up to brake fluid?

 

For a screw-on cap, you could make a gasket from gasket paper. Glue it in the cap with gasket cement.

 

And you need to be sure you leave a vent hole open..

 

Thanks but the gasket is only an 1/8" wide. Not easy cutting out a perfect circle out even with an exacto blade. On my master cylinder the air holes come out of the side of the part that is shaped like a nut. There are two small holes there.

 

I'd try a compass and scissors.

 

Yes!