Clutch bleed now soft brake pedal?

[superpowerdave]

Truck is a 1973 Series III with 77K miles on it. The truck had sat since mid-December prior to our move from North Carolina to Idaho. Once we got here I spun her around the town a little bit and noticed the slave cylinder was going out so she was parked until I got around to replacing the slave.

Bled the clutch at the slave cylinder last night and everything works ops normal except now the brake pedal is soft. When I pump the brake I get no resistance, but if I let off and press again it works just fine.

Did I miss something when I bled the system? One thing I did notice was when I bled the clutch at the slave the system puked out a lot of blackish fluid and I had assumed it was from the pipes - was this a bad assumption?

Other than the double-pump brakes the truck runs great!

 

[eric w siepmann]

Truck is a 1973 Series III with 77K miles on it. The truck had sat since mid-December prior to our move from North Carolina to Idaho. Once we got here I spun her around the town a little bit and noticed the slave cylinder was going out so she was parked until I got around to replacing the slave.

Bled the clutch at the slave cylinder last night and everything works ops normal except now the brake pedal is soft. When I pump the brake I get no resistance, but if I let off and press again it works just fine.

Did I miss something when I bled the system? One thing I did notice was when I bled the clutch at the slave the system puked out a lot of blackish fluid and I had assumed it was from the pipes - was this a bad assumption?

Other than the double-pump brakes the truck runs great!

Sounds like a leak in your brake lines if you have to double pump. Could be dangerous if it is. Check the lines for leaks!

 

[Jason T.]

Many times having to double pump the brakes is an indication that they are out of adjustment. Adjust all 4 wheels up and you will most likely see an improvement. Could also be one of the flex lines getting old and expanding under pressure. Usually, adjusting takes car of the problem.
The dark fluid you observed during the clutch beed could also be a deteriorating flex line or the cylinder seals going south. Maybe it is just very old dirty fluid...
Jason T.

 

[superpowerdave]

I don't think it is a leak in the lines. Fluid is level and no 'new' drips ... I have a few 'old' ones

Jason I'll adjust the brakes and see what happens. I've not done a fluid service on the clutch since I bought the truck so I'm willing to bet it's just old fluid, although a failing MC is always a consideration.

The reason I think it's just old fluid though is because the clutch system was completely fine up until the slave failure. I think as I bled the system it coughed out a lot of crap that had been in there for a long time.

 

[apg]

...and the fact that it coughed out a bunch of black crap is a clue that either the flex lines or the master is going bad, as Jason T. said. For the most part, the clutch piping is solid tube, but there is a flex line hidden well behind the engine. It may be the toughest component on the Series III to swap out - unless the motor or tranny isn't where it ought to be....

Ditto on the brake lines, 'cept there are three flex lines. What is happening is that the softened line(s) is swelling under pressure, requiring the double pump. Check by clamping off the lines: make a non-damaging hose clamp by slipping short lengths of 3/8" iron pipe over needle-nosed vice grips. Clamp off the lines. The pedal should now be rock-hard. If not, the master needs rebuilding. While you are at it, you may want to replace the reservoir, as the plastic is quite susceptible to UV degradation. It can only be removed destructively....

Cheers