Flushing master cylinder and lines

[SUX2BU99]

While getting my rear end back together, I tried bleeding the rear brakes lines but was doing it the totally wrong way since I was doing it by myself and had nobody to hold the pedal down with the bleeder screws closed so I succeeded in emptying my rear reservoir of the master cylinder. Opened it up and holy cow was my brake fluid in the front reservoir ever nasty!!! Looked kinda like chocolate milk    So I guess it's time for a flush.

I found this thread which has some very good info:
http://forum.73-87chevytrucks.com/smforum/index.php?topic=5127.0

I thought about removing the MC from the truck and cleaning it up, etc and bleeding it on the bench but I'm concerned something won't go back in correctly and my brakes will be screwed, like the rod or whatever from the booster won't seat properly. Is this pretty dummy proof?

My Haynes manual describes that you can bleed the MC in or outside of the truck. In the truck shouldn't be too hard with a helper to hold the pedal down and either using plugs for the brake line ports or using a finger pressed firmly over the hole while the pedal is being pushed in. I might just try this route.

Something I found sorta odd was it seemed that the rear reservoir only controlled the rear brakes, since the fluid from the front reservoir never really changed when I had either of the rear bleeders open. Aren't the brakes hooked up in a criss-cross fashion for safety so that if one reservoir is empty, you can still get one brake on the front and the opposite on the rear to work? Maybe I'm wrong about that.

Any hints, tips or tricks? I figured I'd get a large bottle of DOT3 fluid and start getting it flushed. I read something in a thread about a valve on the rear reservoir that can close if it goes empty and makes the rear brakes not function? Is this correct? When I put more fluid in it, I could hear my rear brakes actuating so that's good.

Oh, anybody know what size of hose is a good one to fit the bleeder screw? I don't have a reel of different hose sizes sitting in my garage to try

[Captkaos]

If you are going to flush the system. leave the master hooked up and run the bleeders from the bottom back to the top and bleed it on the truck.  Taking it off is pretty straight forward though, just not necessary.   Then I would hook the lines back up and gravity bleed or manually bleed the system as outlined in the post.

[SUX2BU99]

Okay cool. How does one run the bleeders back into the top of the MC if the brake lines thread into the MC body? Meaning, there isn't anyway to just slip a hose on the brake line ports and dump back into the top of the MC right? A person would need a new pair of shorty brake lines to thread into the MC line ports and bend them up over to the top of the reservoirs.

[Blazin]

Yes short brake line with clear rubber hoses works well, this way you can see the bubbles, or lack of them any way. although if you use steel all the way you can dip the ends into the fluid, then its a one person job!
The master is divided in half. Front, and rear.

[SUX2BU99]

If I do the thing with the lines in the bottle of fluid, I can do it by myself? Is that because each time you let off the brake pedal after pushing it, air doesn't have a chance to be brought back into the line? I wouldn't then need my wife to keep the pedal down while I close the bleeder screws, do a few more pedal pumps, hold down, open screw, close screw, release pedal, blah blah blah?

[eventhorizon66]

I wonder if those speed bleeder screws are any good?  They have a check ball in them to prevent fluid/bubbles from being sucked back up when you release the pedal.

[SUX2BU99]

Hmm dunno. I don't think I've ever seen those. Do you leave them in all the time?

I keep reading that in the 'old' days when rebuilding master cylinders was more common, bleeder kits with port plugs and drain hoses were often thrown in when buying the rebuild kit. Are these plug and hose setups still available? And no, I don't want to buy the professional kit with a hundred different pieces for $90 that a mechanic who might need it weekly would buy!

[SUX2BU99]

I saw a little kit at NAPA to bleed the MC but I bought a $5 siphon pump at Walmart and drained the two reservoirs and now I just have to fill, bleed (in truck, with my wife to help) and then gravity bleed all the brake lines. Should be easy enough I hope!