Manual Master Cylinder Bleeding 69 GTO/Lemans
 

Pleading ignorance but could/should/can the master cylinder be bench bled with the hold off valve as pictured or just the master alone? I'm in uncharted territory here as this is part of my front manual drum to disc brake conversion, and my drum brake setup didn't have the holdoff.
Thanks for helping.

Well, the assembly is mounted in the car. Bled the master per instructions. I guess nobody has dealt with this so I'll wing it.

Wish I could answer your question, but I don’t know. Been viewed 116 times. Hopefully someone can answer this. Good luck.

I've replaced the master cylinder twice that I can remember in my 69 but I never removed the hold off valve. Just bench bled the new master and then bled the rest of the system. Check the service manual on the bleeding process with the hold off valve.

I have an old original 69 service manual but didn't find anything about this. Maybe it's just part of the line bleeding process. I'll find out tomorrow when I start bleeding the brakes. Probably going to be an adventure chasing leaks, with all new front disc brakes, lines, master, etc. Thanks.

I heard or read somewhere that you're supposed to hold that little black button in while bleeding the brakes for that line(front I think). If I'm wrong, someone please correct me.

Bench bleed without the hold-off valve then install and bleed system.

/\ /\ /\ Did it this way yesterday. It worked.

Congratulations!

Finally wrapping up my front end overhaul. Most everything torqued, greased, etc. Also replaced the pitman seal in the steering sector. After bleeding the brakes, I'm pretty happy with them. Replaced the original master cylinder with a Leed unit. Took a while to stop the leaks in the new lines but am good to go now. Now the whole front suspension and brakes are "as new", only now with disc brakes! Front end alignment coming up.