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Discussion Starter #1
Hello again, I have questions about the clutch master cylinder. I've been having problems with it going out when i drove the care for any distance really and i thought it was over heating so i wrapped my headers to prevent that and i still am having the same problem. So i thought i had an air bubble in the line, so i re-bled the line, twice. Second time the clutch wouldn't even bleed. turns out liquid from the reservoir wasn't even getting into the line. So i took the clutch master cylinder out and apart to try to diagnose the issue and realized that (at least) the rubber parts needed replaced so i ordered a rebuild kit and honed the cylinder while i waited for the kit to come. As i cleaned out the cylinder good, i noticed several places that looked like little chunks of the cylinder had chipped out. Naturally, i thought that i'd need to replace the cylinder. I decided i'd just try the rebuild kit since i already paid for it so i did. im having the same problem of not being able to bleed the clutch. I don't know if the chips in the cylinder would cause this or something else so i thought id ask you guys and see what you think. Any help is greatly appreciated and welcomed
 

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The master cylinder bore has to be essentially perfect otherwise it'll chew up the knife-edge of the seals. But it should work even if only for a little while. How is the flexible hose at the slave cylinder? They can fail internally (blocking fluid flow) but look OK on the outside. Usually it is advised that when one component of the hydraulic system needs replacing to replace them all - master, slave & flex hose. It is little more work and then you'll know the whole system is 100%.
 

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I agree with Eric - sounds like it could be a flex hose that has swollen internally, and no longer passes fluid.

One other possibility - when you re-installed the slave cylinder, did you orient the bleed screw at the very top? If the bleed screw isn't at "12:00", then you cannot remove all of the air from the clylinder.
 

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Discussion Starter #4
I didn't take out the slave cylinder, just the master. im not sure that a collapsed hose is the answer either because no pressure builds up when i push the clutch. air is getting all the way through the line, but no fluid from the reservoir.
 

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If no fluid is getting from the reservoir into the master cylinder there must be a blockage. The reservoir is either screwed or pressed into the top of the master cylinder to provide a supply of fluid via gravity. When the pedal is released the cup shaped rubber seal should retract far enough to expose the supply path - a small hole in the top of the cylinder's bore. When the pedal is pressed down & the push rod moves the piston the fluid inside the bore is supposed to be captured by the cup seal and pushed out to the slave.

So, if that ain't happening then either the supply is blocked between the reservoir & the master cylinder or the seal is not moving past the supply port. How is the clutch pivot shaft's weld? If that were to fail perhaps the seal is not moving back far enough to get past the supply port?
 

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Another thought is that bleeding hydraulic clutch systems is often problematic - especially if only the master is disconnected (leaving the lines & slave with fluid in them). The problem is you are trying to push fluid down against any air (that naturally wants to go up...). What I've always done is to reverse fill the system. Using a large syringe I push fluid up via the slave's bleed screw. (make sure the reservoir doesn't overflow as brake fluid is a good paint remover)
 

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Discussion Starter #7
i know for a fact the reservoir isn't blocked, i took it out and cleaned it good too, but ill try adjusting the plunger to sit further back in the cylinder and see if that does it, thanks for the idea
 

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I'm still getting the same result after adjusting the plunger. I noticed some black fluid (most likely old brake fluid) leaking out of the slave cylinder which is making me think it might be worth it to just replace both cylinders and the rubber connecting hose just to be safe and make sure the whole system is in good condition. your thoughts?
 

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I agree that it is usually false economy to replace only one part of a hydraulic system. When one part needs repair/replacing the other parts are usually also at the end of their service life. Doing them all together is only a little bit more work to do once and, since it is likely you'd otherwise have to replace the other parts soon, it is not more money in the long run.

One other thing to check while you are working on the clutch master is the push rods length. Although it is adjustable it is not meant to be adjusted during service but rather adjusted for its specified length on installation then left alone.
 

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Does anyone know where I can get a service kit for a clutch master cylinder for standing ( floor pedals) ?
I have a European 69 spider right hand drive.
All RHD had standing pedals with MC under the floorboard.

Much obliged

Robert
 
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