New Clutch Master Cylinder
 

I had a leaky clutch master cylinder (dripping down below pedal) so I started the replacement earlier tonight. I swapped the slave cylinder bleed screw with a speed bleeder as well. I dissasembled and ressasembled with no issues and poured a bit of brake fluid down the top black hose that attaches to the brake master. I got barely any pedal pressure after many pumps and when the brake fluid did finally stat to flow it became very frothy and then I lost pressure all together again and cannot get it to come back up. I checked all connections and everything is tight. I am considering the possiblility that the speed bleeder is leaking past the threads. I only opened it a quarter turn to bleed.

After researching on the forums I see alot of people have simply filled the clutch master with fluid and had little trouble bleeding. Where is the correct spot to pour the fluid into? What would be the proper way to bench bleed these cylinders? I also have a vacuum pump that I could hook up with the original bleed screw but im not sure that will work in this case as I can't get the clutch master to pump any fluid.

Any insight and pointers are appreciated!

Update:

I did end up having to attach a crappy vac pump to the original bleed screw to get the fluid to flow. Had my shop bleed the rest of the way with a pressure bleeder once I got it driveable. Sorry for the desperation post lol...I know this has been covered many times.

CMC replaced - Clutch pedal super stiff when hot then fails
 

Hello everyone,

I had replaced my clutch master cylinder over a week ago. Everything went smoothly. Bled the lines, replaced old brake fluid with new DOT 3 brake fluid, and the car was running like it should. 2 days later, as the car got to heating up while driving, the clutch would progressively get more stiff until there was no free pedal play left up top. From this point, the next push of the clutch pedal would drop it to the floor and it would be stuck with no pressure. I then pop the hood, crack the bleeder valve, close it, lift the clutch pedal by hand, and everything is all good again. As I continue driving the clutch would progressively get stiff again and, "pop", it'll fail... again.

I've been popping the hood to crack the bleeder at least once a day. What is going on with the clutch system? Is my new master cylinder faulty? Is the slave failing? Is there some sort of pressure release valve within the cylinders? Why is so much pressure building up in the system when it never did before?

I don't understand....