I've got a hydraulic clutch on my MK, it's all plumbed in okay with no leaks. It seems to bleed okay, it gets nice and firm and moves the clutch release arm perfectly... but it only does this for maybe 20 or 30 pumps, over which time it fades until I can't change gear anymore.

There are no fluid leaks, there surely isn't trapped air as it was working fine... what could the problem be? Letting air in? Problem with the slave cylinder in the gearbox?

I've got my engine out at the moment so I want to get it sorted while it's all easy to get to

What sort of flexible hose are you using? if its an old rubber/nylon one, they can as they warm up, swell as you press the clutch, hence fluid transfer to the slave is reduced.

[Edited on 27/5/09 by r1_pete]

[Edited on 27/5/09 by r1_pete]

I've not got flexible hose yet, just a copper line to it to test it

Where could I get a flexible hose made btw? I'm not sure what threads are at each end...

Is the pushrod into the M/C straight, I had a problem with a M/C due to the push rod not being square, and this caused some marking on the inner surface of the cylinder and was allowing air into the system (but no leak) through the primary seal..........or this is what I believe was causing my problem

Do you get air out when you re-bleed it, after is starts dragging? if so air must be getting in, check all your connections.

Maybe the seals are starting to fail as they warm up in use.

I got my flexies from Furore Cars, best vfm I found, sure he's on here too.

quote:

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Originally posted by r1_pete
I got my flexies from Furore Cars, best vfm I found, sure he's on here too.

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quote:

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Originally posted by r1_pete
What sort of flexible hose are you using? if its an old rubber/nylon one, they can as they warm up, swell as you press the clutch, hence fluid transfer to the slave is reduced.

[Edited on 27/5/09 by r1_pete]

[Edited on 27/5/09 by r1_pete]

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Is the pedal going completely solid after X pumps ? or is the clutch no longer clearing ?

If the former you need a return spring on the slave cylinder
If the latter you have air getting into the system.

quote:

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Originally posted by britishtrident
Is the pedal going completely solid after X pumps ? or is the clutch no longer clearing ?

If the former you need a return spring on the slave cylinder
If the latter you have air getting into the system.

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Bumpz0r.

I've just refit the clutch since engine rebuild and I've tried to bleed it again. I've got a proper clutch hose made up and I've used PTFE tape round all the joints, crush washers in the right places and double checked everything. I'm sure the hose is tighter than a.... Every time the pedal is pumped some clear liquid comes through, then a fine mist of bubbles so it looks milky.

I've phoned OBP and they'll happily replace the unit for me (good on them) but I just wanted to check... is it possible that the problem is the slave end? Ideally I'd take off the hose at the slave end and watch the liquid when being bled, if all clear then it would comfirm that M/C is fine... but I don't have anyone to help me bleed the clutch until monday (can't find eazi bleed kit anywhere)