93 Accord EX - odd brake problem

I have an intermitent problem with the brakes on My Accord. Every so often - seems to happen more in high temps?? - The brake pedal will slowly go all the way to the floor as I apply the brakes, there is some pressure and the brakes work, but i have to pump them. At 194,000 miles I'm suspecting the master cyclinder might be due for replacement, --- any other advice appreciated

No one need reply, I did a little better search here and found my answer. I think I'll replace the master cylinder and bleed out all the old fluid.

Probably the M/C, like you said, but very old and contaminated fluid will also have so much moisture content, it'll vaporize during real hot weather or heavy usage, and make the pedal fade and drop like that.

Regardless of what you end up doing, replace the fluid with Valvoline SynPower DOT 4 (or a similar product) and you will never have problems with temp related fade and resists moisture contamination better...

I'm glad I saw this discussion. I have the exact same problem with a 91 Accord and have been wondering what the cause might be.