Master Cylinder Cap Gasket??

Anyone know where to source a replacement gasket for the brake master cylinder cap? Mine is very brittle and now leaks... I'm retrofitting a Ford Ranger remote reservoir similar to the Dr. Vern writeup, but now I can't get the darn m/c cap to quit leaking from the gasket. Will an appropriately sized o-ring do the trick? Is there any sort of DIY gasket goop that might work? Any and all ideas would be welcomed!! Thanks!

 

Use a nitrile or brake fluid compatible o ring. Just did a similar conversion and that's what I used and works fine so far

 

No goo. If it is an OEM master cylinder, any parts supplier could get the seal, take the cap with you. Copper is best in my opinion but very hard to find NOS. You might check with Walcks, Midwest Military, g503 or Willys Overland.

 

I've got some bulk cork gasket sheet... Is cork compatible with DOT 3 brake fluid?

 

I found a nylon washer at the local hardware store that was close to the right I.D. and after some quick work with my Dremel, it fits like a glove and appears to hold thus far!