Drain the fluid?

[primerib]

This is a noob question, but being a noob I must ask.

I am swapping out my master cylinder. I am about to disconnect it from the line going to the slave. The instructions say nothing about draining the existing fluid, it skips right to the unbolt section. Being an expert on spilling stuff, Is my assumption of connecting a hose to the bleed valve and pumping the old fluid out, a bad one? Or should I remove the fluid and then refill after? I just want to make sure that I am not about to do something stupid?

Thank you!

[mearstrae]

Drain out the fluid or you will have a mess, and brake fluid does a good job of removing paint. Catch all the fluid in a container at the slave end, and pitch it out. After you've got the new master in place fill with new dot 4 fluid and bleed the master to get rid of air on that end, before hooking up the line to the slave [I use an old piece of line and pump the master into a container]. Hook up the line and then refill the master and bleed the whole system of air at the slave, keep it full while you pump or air will get back into the system. A vacuum bleeder works well for this but isn't essential.

'95 R.R. Classic LWB
'76 Series III Hybrid 109
'70 Rover 3500S

[primerib]

Thank you! That is what I figured, and the advice of bleeding the master first is helpful I will try that!! Thanks! I will let you know how it goes...Aiming for friday!