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Discussion Starter #1
I’ve changed the clutch master on a 156 TS as the old one was leaking and I never had a consistent pedal. I had several secondhand ones that came from cars that all had good clutches before the parts were removed so I reasoned one of them at least must be working. I’ve fitted all of them and yes I can get a clutch and the pedal stays up but the system is full of air just can’t get rid of it. I can’t find any leaks and have repeatedly bled the clutch but every time I pull the clip up and slide the delivery pipe to the slave out slightly there’s a cascade of bubbles as if the brake fluid is fizzy it’s positively foaming with air. Now, the feed from the reservoir goes straight to the master so I’ve assumed that the problem is either in the feed to the master (I had to replace the round seal on the delivery pipe that goes into the back of the master but I can detect no obvious leaks from it) so one of my my questions is where is the air getting in? Where does the hydraulic fluid go after it passes through the slave?it must be recirculstrf but Im not sure where of its route that’s what I want to check to see if there’s any breaks snywhete. I’m not losing any hydraulic fluid so I don’t think the slave is leaking unless it can amit air without leaking fluid? The bubbles appear immediately the bleed pipe is opened..As I say I can’t believe all the master cylinders would be scrap as all the cars they were off had decent clutches. Just one other point at one b point the reservoir nearly completely emptied of fluid while I was fitting one of the masters so I expected there to be a lot of air but I’ve gone through loads vin of hydraulic fluid and the frothy mix is not improving. I also tried bleeding the offside front brake to see if there was air in the brake circuit but ybeteWould be grateful for some advice please?
Also does anyone know where you can get seal kits for these master cylinders?
Cheers
 

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Discussion Starter #2
Meant to say there is no air in the brake circuit as checked at the front offside calliper anyway
 

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Should be three pipes coming of brake fluid reservoir. One for clutch, one for one brake circuit and one for another circuit. In theory there could be a leak in one of those three circuits and the other two will be fine.

When you bleed the clutch, at the slave I assume? I'm not sure how much different the 5 speed is to the 6 speed do you use a helper or a vacuum pump? I find clutches very difficult to bleed alone. I do not think there is a return line. It's just like the brakes, there is just one line to the brake caliper/slave cylinder.

The air could be getting into the line right at where you are bleeding it. Is the hose securely attached to the bleed nipple? And of course, make sure you don't let the reservoir run dry when bleeding! But use a helper if you are not already.

Maybe the slave is leaking and needs replacment?
 

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Discussion Starter #4
Thanks. Yes I’m bleeding it at the slave and I’m hoping that the slave isn’t the issue or it’s a big job as you know on the TSs as it’s inside the bell housing. I’m working solo releasing the clip extracting the pipe a few mil back from the nipple then pushing and trapping the clutch pedal down to the floor where it would stay pretty much anyway!, then pushing the pipe back in and dropping the clip into place and have repeated the process many times then tried to build up pressure in the clutch with repeated pumping while the clip is closed. There’s certainly a pedal there after that and it’s right up so I’m keeping my fingers crossed I’ve just got air in there. The brake callipers are all good and I can’t see any fluid leaks on any of the lines going to them and the level in the reservoir is constant I’m not sure there can be a leak. I’m going to get a Gunson Eezebleed and see if it helps. The reservoir dropped practically to zero when I was grappling with the master it really is a pig to couple up and lock the slave pipe to in the engine bay so a lot of air got in.
 

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On the TS, the bleed port is on the slave cylinder pipe where the flexible hose enters it. Normally it bleeds easily enough but it may be useful to know the theory details.
When bleeding by pumping pedal or however, the slave cylinder needs to be charged up. Normally pumping works very well as the fluid enters the clutch slave cylinder but when the pedal is raised, any air in the slave cylinder moves to the top and then into the integrated pipe where it can exit through the bleed port. For that reason, even when using a pressure bleeder, it may be necessary to turn air pressure on and off repeatedly.

I once heard of a Traffic/Vivaro/Primastar van which could 'lose' it's clutch pedal if not used for a couple of days. After a master cylinder and a flexible hose were tried a gearbox out and new concentric slave cylinder was the thing to cure it.
 

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Discussion Starter #6
That’s interesting I’m surprised I haven’t cleared it with the standard procedure so far so perhaps it is the slave but if it is wouldn’t you expect fluid loss in the header tank?
 

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Yes, that one doesn't make sense to me at all. Anytime there is a leak at the slave cylinder, I expected fluid loss. I think that becomes the last thing to try given it is a CSC.
 

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Discussion Starter #8
The Gunson cleared it in a trice! I must have been close doing it manually because there was just one shot of fizzy fluid and a few straggler bubbles and it was a solid stream. Clutch is excellent now. Glad I didn’t have to think about getting it out, though it’s a job I’ve got to try someday. Incidentally I bought a genuine Alfa hose for the master but I wish I’d just used 6mm brake pipe and trimmed it after it had been fed through the grommet in the firewall the Alfa one was so short it only just goes over the flared end of the slave delivery pipe and that was after lubing it with hydraulic fluid and eventually using brute force to extend it just hope it doesn’t leak when everything warms up. Putting that master in was an awkward job I’m going to post a how to do it guide on here.
 
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