I put on some Goodridge SS front brake lines not too long ago on my '93 F2. Ever since then my master cylinder has been leaking from the cap. I've tried to tighten it down, but to no avail. It's annoying because brake fluid gets onto my brake lever, and the fluid causes my glove finger to get damp, which in turn causes my gloves to bleed black dye on my fingertips.
So, 2 questions:
1: There is a white plastic piece inside the cylinder, and a black rubber piece (seal?) inside the cylinder. Could it be that I have one or both of these out of position that's causing this?
2: I have some clean brake fluid left over from the install (it's about a month old). If I screwed the cap on the bottle tight is this considered "from a sealed container?" Is it safe to use to top off the brakes, or could it have absorbed some moisture? Should I just go out and buy some new fluid?

OK, so maybe that's more like 4 questions, but oh well. I'm not too knowledgeable on brakes, so info is much appreciated! Thanks in advance!

 

the seal is likely your culprit.
clean the mating surface between the lid and the MC resevoir.
for the white plastick and black seal part...put the seal over the plasic then install it on the MC then the cover. then toruque both sides of the cover down to the proper spec...or just tighten the sucker.

you're not getting a good seal between the lid and the MC resevoir, most likely from improper install of the seal or improper tightening of the lid. if one side is tighter than the other, the other side may leak.

as far as the fluid...it most likely has absorbed some moisture. only way to have none is to suck out the air from it then cap it...cause air has water in it. but after a month, i would still use it....but that's just me and i bleed many times per year...so it's all good! but if don't rarely bleed, then get a new bottle.

 

Thanks for the quick reply, Tahoe! I'll go try it out right now!

 

OK I took off the master cap and the black seal looked a little distorted (like it got folded up wrong when I sealed it last time.) So I straightened it back out, topped off the fluid, reinstalled the cap, and cleaned everything up. I'll go for a ride and see if it leaks now, and I'll let ya know.
BTW, I know that brake fluid will eat up a paint job, but it sure does make dull black plastic look shiny and new. Don't know if it's safe to use in that manner (probably not) but I got a little drip on the outside of the cylinder. After wiping it off with just a clean towel, the master now looks almost new.

 

HAHAHAH it ate up the grime that was there probably.

pump up the brake system and give it a bunch of squeezes to see if you can see bubbles oozing out or anything from the sides of the cover that has the notches cut into them.

 

Might have to get a new gasket or seal. Probably like $2.00.

 

I rode about 20 miles yesterday, & it doesn't leak anymore. At least not from the front. I think I will just have to keep playing with the placement of the seal if it gets on my nerves again.