Originally Posted by
FBinNY
Is it at all possible that the valve is OK, and the leak is related to all the rust at it's base?
Removing the fork from the bike, and using a bucket of water, one should be able to locate the leak.
Valve cores are often replaceable, and are pretty standard. So, if the core is leaking, then that would be a quick fix.
If the treads where the valve are screwed in are leaking, then some teflon pipe tape or goop might help.