Master Cylinder Bench Bleeding

[mike42]

I'm getting my MC tomorrow and was told to bench bleed it before installing. So.....what is that and how do you do that ?

Thx.....Mike

[rockfla]

Clamp it into a vice, I have a couple of old brake lines that I cut about 3 or 4 inches long to thread into the brake line outlets, fill the master cylinder with fluid, attach a couple of rubber lines to the brake line stubs (or run the rubber hoses into a jar of brake fluid so it can pull fluid as well as push fluid), put the rubber lines back into the cylinder and slowly push the plunger in and out to bleed off any air in the master cylinder. Keep pumping until you don't see any air bubbles in the cylinder or if you use the extra bottle till you don't see air bubbles In either location.

[Cecil/WV]

Probably not the most scientific way, but I clamp it in the vise and fill the reservoir and push the piston in with a big phillips screwdriver and hold my finger over the outlet before I let the piston return and repaet the process until there is no air comimg out and then put a plug in the outlet and install it on the car. Has worked for me for over 50 yrs. Most modern replacement cylinders come with a short hose to put in fluid and you can stroke the piston back and forth until the air is all out.

[mike42]

Okay guys....thx !

[Jack E/NJ]

Bench bleeding seems like such a messy waste of time & effort.

Jack E/NJ

[Speedy Canuck]

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Originally Posted by Jack E/NJ

Bench bleeding seems like such a messy waste of time & effort.

Jack E/NJ

It's a lot easier and less wasteful than pumping air into your entire brake system and having to bleed extra air out of the whole system...

[SofaKing]

[QUOTE=Cecil/WV;1325588]Probably not the most scientific way, but I clamp it in the vise and fill the reservoir and push the piston in with a big phillips screwdriver and hold my finger over the outlet before I let the piston return and repaet the process until there is no air comimg out and then put a plug in the outlet and install it on the car.

I knew a guy that did it this way and got out of sequence. He injected brake fluid into his thumb through the skin. He was hospitalized for weeks, out of work for months and his thumb was never the same.

I installed a new Cardone MC last week and it came with plugs to bench bleed.

[A bones]

Yeah,,,, I tried earlier to post but my computer is screwed up. What I would have said has been covered - (plastic hose to return to reservoir, 'til bubbles cease) - except this: Wear gloves its nicer, and just because someone wants to refute; the empty master has no POWER. Once bled and full of fluid you can push the air to, through, and out of the wheel cylinders. AND that is why bench bleed is necessary!

[Jack E/NJ]

>>>AND that is why bench bleed is necessary! >>>

OK, I can't help myself here. No bench. I mount it dry on the car. Then bleed it unconnected. Then connect it. Then bleed the whole system again. Less mess. 8^)

Jack E/NJ

[mike42]

I'll give the bench bleed a shot and go from here. I pick up the MC in the morning.

Thx all......Mike

[A bones]

Originally Posted by Jack E/NJ

>>>AND that is why bench bleed is necessary! >>>

OK, I can't help myself here. No bench. I mount it dry on the car. Then bleed it unconnected. Then connect it. Then bleed the whole system again. Less mess. 8^)

Jack E/NJ

Very tricky, so then, instead of a vise you use the car. I get it.

[mike42]

Not a hitch. MC went in no problem. I went with the Reman, as the new was from Tiawan !

Need to bleed each wheel but no leaks at all !

Thx

[mike42]

Just opened the box with Russell Speed Bleeders. Can I bleed brakes by myself with these ?

[19Fordy]

Yes. Just follow the instructions.

[325w]

Last new master I got had no plastic stuff to help bench bleed. Took it back went to another auto store same thing. Jump all over the 16 yr old manager. He gets a paper they were given. Just plug the outlets and pump very slow till no bubbles. Worked like a champ.

[mike42]

I've got the MC installed and did the bench bleeding and that worked out great. I pushed in the plunger with wooden dowel until I could not push in anymore. All is well. Mine had the plastic plugs in box.

I had some Russell Speed Bleeders I bought a few years ago, but no instructions. Do these fit into the rear of backing plates near the top and can I bleed them by myself or still have someone pump the pedal ?

Thanks for all the help. I haven't done this for 55 years and can't remember what I did back then !!

Mike

[A bones]

I never use help when bleeding wheel cylinders. In a different world (many moons ago) an old Packard mechanic explained it like this.

If the bleeder valve is open, and the installed shoes have return springs to hold them, the wheel cylinder pistons won't move when the pedal is depressed. All that happens is the fluid (with air bubbles) flows through the line and exits the bleeder valve, once the wheel cylinder is full.

By watching and listening one can determine when- (I work the pedal by hand and look beneath the car)- the flow is steady (no air). At that time close off the bleeder valve. As usual, be sure to keep fluid in the master reservoir. I check it every third stroke. Also as usual, begin with the wheel that is farthest from the master.