Bench Bled?

LostHuman · Post by **LostHuman** » Fri Sep 10, 2004 3:31 pm

I notice peole talking about the master cylinder being bench bled... educate me, and tell me what that means? I am racking my head

trying to figure out what that means... thanks...

scoutski · Post by **scoutski** » Fri Sep 10, 2004 5:26 pm

This refers to bleeding the master cylinder while it is out of the vehicle and on the work bench.
The procedure is to make a closed loop by attaching a fitting to the outlet/s and routing a piece of tubing from this fitting/s back into the resevior. Fill the resevior with brake fluid then push the piston in and release it. Continue doing this untill no bubbles appear from the tube/s. Be sure to keep the ends of the tubing submerged in the fluid.
This makes the brake bleeding at the wheels faster as you are not pushing a slug of air thru the brake lines.
My 2c.

nfury8 · Post by **nfury8** » Fri Sep 10, 2004 9:39 pm

Bench bleeding is critical when replacing a master cylinder. It can take a while, but it will take forever if you try to do it on the vehicle.

Part of the process is to make sure and push the piston ALL THE WAY in on the bench. If most likely isn't possible to depress the piston all the way when on the vehicle.

LostHuman · Post by **LostHuman** » Mon Sep 13, 2004 10:41 pm

Thanks for all the inputs and for educating me.. it went well... trucks stops nicely. Thanks again.

Post by **Hobcobble** » Sat Sep 18, 2004 7:27 am

"Bench Bled"
This term also applies when the sharp screwdriver you're using to push
in the piston slips and goes clear through your wrist on the arm you're
using to hold the top of the master cyl. steady.... [also known as a
partial crucifixion]. Always try to use a blunt object

John

nfury8 · Post by **nfury8** » Sat Sep 18, 2004 3:08 pm

Good Definition!

A vise is also highly reccomended to hold the Master Cylinder!

thorman · Post by **thorman** » Sat Oct 09, 2004 3:12 pm

[quote="nfury8"]Bench bleeding is critical when replacing a master cylinder. It can take a while, but it will take forever if you try to do it on the vehicle....[quote]

Hey I,m new to this site and have a question about bench bleeding. I bench bled a rebuilt master cylinder for my 70 D100 last night and was planning on installing it today. Now I'm concerned that I might not have bled it enough. When do you know when the bleeding is done? I know that there aren't supposed to be any bubbles in the fluid, and I thought I'd done that. I'm still getting miniscule bubbles in the bleeder tubes that don't seem to be going away. A little help PLEASE!

Post by **Goldie** » Sat Oct 09, 2004 6:38 pm

If you are sure all your fittings are tight and you have kept the ends of the tubes from the reservior submerged in the fluid, then the bubbles will eventually all disapear. some patience may be required but it will happen. The bleeder kit is usually supplied with a new master cyl. but not always. They are available separately. The whole idea is to get the air in the master out before you hook up your brake lines to the wheels. If you do not bench bleed, you can get the air out eventually, but I don't want to be the one helping you do it. Possible leaving the master sit level overnight so the air bubbles can form one bubble may help. Good luck and have patience..............Goldie

thorman · Post by **thorman** » Sat Oct 09, 2004 9:07 pm

Thanks Goldie, I let the master cylinder sit in the vise overnight after bench bleeding it, before reinstalling, and that took care of the problem

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