Clutch pedal lost pressure

[CroneOne]

Hi guys

Hoping some of you can't clear up some technical info.

I started up my car and a 30 seconds later I noticed that my clutch pedal had
lost all pressure -but not the brakes. It wouldn't push back to my foot and I couldn't engage the clutch.
Switched the car off for 10 minutes. Some pressure had regained and I was able to shift however
it soon lost pressure again.

Does the Fist's clutch pressure use the same master cylinder as the brakes?
It was confusing because the brakes still had pressure.

My first thought was that I had air in the brake system. I bled out the rear
brakes and there's no air in there. After I bled the brakes and started
up again my clutch was working. Drove around for 5 minutes without
problems....but I'm slightly paranoid to driving around now.



Curious. Any info would be great and appreciated thanks!

 

[me32]

Odd maybe it was a fluke

 

[CroneOne]

After some search action, I have a feeling the master cylinder seals are gone or
something is letting air into the clutch hydraulics.
Found a great diagram of the clutch fluids lines here

http://www.fiestastforum.com/forum/threads/935-Brake-Clutch-Fluid-Check

I think pressure is being lost between the master and slave cylinder.

My pedal still feels way too soft and it isn't springing back

 

[_Hunter702]

The clutch runs off the brake master cylinder so if you didnt bleed it right it could cause that but check and see if any fluid is coming out.

 

[CroneOne]

I've only bled the brakes via the caliper bleed bolts but there were no bubbles coming through there. Is there a bleeder on the master cylinder somewhere? I've been Googling but it's tough to find info.

 

[lukits01]

Not sure if it's the same failure, but my clutch slave cylinder failed recently (number 6 in the picture below)

Clutch pedal lost all pressure without affecting the brakes. The clutch fluid was leaking pass the seals in the slave cylinder and dripping out of the gearbox case. On close inspection the part itself is quite a cheap part made of mostly soft plastic, wouldn't be surprised if some of these would fail prematurely.

 

[CroneOne]

Interesting. I was hoping it would be something obvious like this but
there were no leaks and my brake fluid was full.
Took it down to the Ford shop and they did all their
checks and couldn't find anything. Absolutely bizarre.

The only thing I'd done before that is change the rear brake lines to SS lines but
I made well sure that I bled them perfectly. Not only that but if there
was air in the brake lines the brakes would be mushy not the clutch.

My only other guess is that I had bad brake fluid in the lines. I use Motul
rbf600 ... perhaps the ST doesn't like it? Mystery.

 

[lukits01]

Interesting. I was hoping it would be something obvious like this but
there were no leaks and my brake fluid was full.
Took it down to the Ford shop and they did all their
checks and couldn't find anything. Absolutely bizarre.

The only thing I'd done before that is change the rear brake lines to SS lines but
I made well sure that I bled them perfectly. Not only that but if there
was air in the brake lines the brakes would be mushy not the clutch.

My only other guess is that I had bad brake fluid in the lines. I use Motul
rbf600 ... perhaps the ST doesn't like it? Mystery.

I've been using RBF600 for almost a year now, god I hope that's not the cause haha