master cyl question

[slepysal]

what would cause my master cylinder to leak from the top? I find that after a while I lose brake fluid due to it leaking out. I plan on converting to disc brakes and swaping the master cylinder out, but I am still curious about this.

[3speed 6cyl]

Replace your gasket to your master cylinder top. I recently instaled my disc power brake set up and it was tight as heck to get my top bar over the cover. I had to use a towel to get extra grip to close it so take off that bar and bend it in a way that it would be a tight fit. Look closely at your brake line connection to the master cylinder, it might be that. wipe everything clean and dry to see exactly where its comming from. If it's the brake line connection use plummers tape(5-10X around stretched good) for EZ fix. Most likely the bar is worn loose from off/on ware(common).

[Brad54]

Originally Posted by 3speed 6cyl

Look closely at your brake line connection to the master cylinder, it might be that. wipe everything clean and dry to see exactly where its comming from. If it's the brake line connection use plummers tape(5-10X around stretched good) for EZ fix. Most likely the bar is worn loose from off/on ware(common).

If it's coming from the connection, do NOT use plumbers tape. Plumber's tape seals threads. On a flare fitting, the union is a flare on the end of the steel tubing, and a seat, or nipple in the other end. The screw threads on the fittings simply hole the tube against the seat really tight. If there is a leak, it's leaking past the seat and will escape between the tube and the nut that slides over the tube, not past the threads.
If it's leaking at the fitting, simply loosen and re-snug the fitting a few times. If that doesn't do it, the nipple in the fitting may be crushed, and you need a new fitting. Had that happen for the first time while I was doing the dual reservoir/power conversion on my '62 earlier this month. I've done A LOT of hard lines, and never saw that before.

Do you have the hydraulic clutch on your truck? It could be the rubber link in the clutch line. That was bad on my truck. If you do have the hydraulic clutch, but don't have a rubber segment in it (because someone removed it years ago), and just have a hard line going from the master to the clutch slave, you could have a cracked line--it needs to be able to flex with the enging rocking.

-Brad

[fercho71]

Originally Posted by 3speed 6cyl

Replace your gasket to your master cylinder top. I recently instaled my disc power brake set up and it was tight as heck to get my top bar over the cover. I had to use a towel to get extra grip to close it so take off that bar and bend it in a way that it would be a tight fit. Look closely at your brake line connection to the master cylinder, it might be that. wipe everything clean and dry to see exactly where its comming from. If it's the brake line connection use plummers tape(5-10X around stretched good) for EZ fix. Most likely the bar is worn loose from off/on ware(common).

I am not an expert sal but i agree with 3 speed 6 cil on a previous car that i heaved it was the master cylinder top gasket that was damaged so i replace it good luck

[slepysal]

The original gasket seems to be made of the fiber type . I picked up some cork, and will see what happens . Thanks for the tips !