My clutch master cylinder is leaking so I am goin to replace that, the slave cylinder, and the convoluted line. I got the new parts in today and am wondering why the Clutch Master cylinder has what looks like a vacumm hose line attachment at the base.
What is that for?
Why does it need a vacuum line?
Where does it go?
What does the line do?
If the current one is old and leaking what effect does it have on the hydraulic clutch?

I believe it is a vacuum assist, that makes it easier to press the pedal.

Thus, if it were leaking, the pedal would be harder to press. May have an affect on something else on that vacuum line, if there is anything.

Ok, that makes some sense.
Thank you!

..............No it doesn't! ...and I am an idiot. I totally forgot that it has a remote resivoir, (shared with the brakes) and the fluid has to get to the cylinder somehow. It is the fluid line, duh. Plastic and with a hose type clamp...who'd a thought?