Bench Bleeding Brake Master Cylinder (1 Viewer)

[kenleyf]

I have searched but I did not find the exact steps to bench bleed a MC. I am replacing the MC on my 1989 FJ 62 and I need the exact steps on how to do this. Do you have to "bench bleed" the MC or can you bleed it once it is installed?

Any help is much appreciated!!

Thanks!!
Kenley

 

[Jan-78FJ40]

I have searched but I did not find the exact steps to bench bleed a MC. I am replacing the MC on my 1989 FJ 62 and I need the exact steps on how to do this. Do you have to "bench bleed" the MC or can you bleed it once it is installed?

Any help is much appreciated!!

Thanks!!
Kenley

Bench bleeding is a complete mess and highly overrated. The following works much better:
Install the master.
fill the reservoir.
take a big zip-lock, pull over the whole thing.
put your fingers firmly on the two outlets from the outside of the ziplock (plastic between fingers and holes)
have someone else pump away the brake pedal.

first, fluid will come out of the first hole.
after more pumping, out of the second hole.
once no more bubbles come (you can feel them pass in your fingertips), quickly hook up the break lines.
Most of the waste fluid will remain in the ziplock, and the mess is much smaller.

proceed with bleeding the whole system.

this takes a fair amount of fluid.

cheers,
J

 

[kenleyf]

Thanks for your help/reply!

How is your method different from using the one-man bleeder system that utilizes dual tubes to bleed the MC? Is there something magical about the ziplock bag over the entire MC? It seems as though bleeding with the two tubes into a bottle would ensure no air gets back into the system.

 

[Spook50]

I have two hard lines that are curved to end in the reservoir of the MC when I bench bleed it. I hook those up, put the MC in a vise (NOT TIGHT! Just enough to hold it in place), fill the reservoir with fluid, then pump away by hand with a metal dowel or anything the right size that can be used as a pushrod. Like was already said, go until there are no more bubbles in the fluid. Then, leaving the "bleeder" lines hooked up, I install the MC in the truck. After placing a couple rags on the inner fender to soak up any spilled fluid, I swap the "bleeder" lines out with the ones on the truck, one at a time. Not a huge mess, but you're guaranteed to drip some fluid. And it makes a great paint remover, hence the rags

And as always when you open up the brake system, bleed everything else once it's all back together.

 

[freds40]

This is pretty much how I do it. I usually hold a finger over each hole and a rag around my whole hand to catch the fluid that sprays out.

After you have fluid coming from both, have the person release the pedal with your hand still over the holes. You can then let go and connect the lines. No air will be pulled in as the system will continue to gravity bleed until the system is sealed.

Bench bleeding is a complete mess and highly overrated. The following works much better:
Install the master.
fill the reservoir.
take a big zip-lock, pull over the whole thing.
put your fingers firmly on the two outlets from the outside of the ziplock (plastic between fingers and holes)
have someone else pump away the brake pedal.

first, fluid will come out of the first hole.
after more pumping, out of the second hole.
once no more bubbles come (you can feel them pass in your fingertips), quickly hook up the break lines.
Most of the waste fluid will remain in the ziplock, and the mess is much smaller.

proceed with bleeding the whole system.

this takes a fair amount of fluid.

cheers,
J

 

[lehiguy]

Thanks for your help/reply!

How is your method different from using the one-man bleeder system that utilizes dual tubes to bleed the MC? Is there something magical about the ziplock bag over the entire MC? It seems as though bleeding with the two tubes into a bottle would ensure no air gets back into the system.

Don't forget you still have to remove those tubes and put the regular lines back on the MC. There is no real difference in the Ziplock bag approach other than it's cheaper, faster and you don't have to screw around with making cute little curved brake lines.

 

[Tinker]

Ghetto method: crank all the bleeder valves open & pour fluid in the MC till you get bored. This from an old friend/post WW2 Chrysler expert/junkyard mechanic. Helps if you're at a Superfund site.

 

[jvazquez53]

MC I bought came with the bleeder lines. All I did was put in in a vise, the two lines go into the MC reservoir, fill the MC, pump it until no bubbles come out. BTW, it was not messy. (learned this method in the USAF)

 

[Cruzerman]

Like Spook50, I have a couple pieces of short hardline that run back into the reservoir. I don't do it on the bench / vise though. I just bolt the thing up and do it right on the rig.

 

[beaufort-fj60]

Ghetto method: crank all the bleeder valves open & pour fluid in the MC till you get bored. This from an old friend/post WW2 Chrysler expert/junkyard mechanic. Helps if you're at a Superfund site.

you can still do this with a 2 liter coke bottle and fish tank bubbler tube on each bleeder nipple.

 

[Spook50]

...just bolt the thing up and do it right on the rig.

That works too. Buuuuut I'm used to doing things the hard way...

 

[kenleyf]

Knew I could count on the forum for some help!!

I did a half @** job of bench bleeding the new MC before putting in on. I finished by bleeding it once I installed it on the truck. I drove it around last night and I had good breaks. I drove it to work today and in Atlanta that means repeated stops and it performed well.

Thanks for all the help!
Kenley

 

[Kanda]

Bench bleeding is a complete mess and highly overrated. The following works much better:
Install the master.
fill the reservoir.
take a big zip-lock, pull over the whole thing.
put your fingers firmly on the two outlets from the outside of the ziplock (plastic between fingers and holes)
have someone else pump away the brake pedal.

first, fluid will come out of the first hole.
after more pumping, out of the second hole.
once no more bubbles come (you can feel them pass in your fingertips), quickly hook up the break lines.
Most of the waste fluid will remain in the ziplock, and the mess is much smaller.

proceed with bleeding the whole system.

this takes a fair amount of fluid.

cheers,
J

This is a great solution. Thanks for the tip - I did this the other day after redoing all the brake lines and it worked like a charm. Cheers.