Bench Bleed the Clutch Master Cylinder?

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I'm installing a whole new master/slave cylinder system for the clutch, and have read references to "bench bleeding" the master. What exactly is this? Is it necessary? Thanks.
 

Pin_Head

 
 
 
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"Bench" bleeding is not necessary, although it is useful if you are working alone. Clutch masters bleed well by just cracking the bleeder on the slave and letting gravity do the work. If there is air in the master after bleeding it, you can just loosen the nut on the line on the master and squirt some brake fluid into a shop rag, then tighten it before sucking air back into the master. This is a two person job.
 
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Thanks guys. The master cylinder and slave cylinder are all "connected" by the same hydraulic fluid, right? So, why would the master need to be bled separately? It seems to me all the air would be released from the slave since it's all the same fluid. Just wondering what I'm missing.
 
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One for the front disc brakes and one for the rear. The picture up above is as good a discription as it can get. You want to make sure to get ALL of the air bubbles out of the cylinder.
 

Pin_Head

 
 
 
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Properly executed, the two person method is fool proof for every application, but clutch masters seem to bleed just fine by gravity.
 

pbgbottle

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i just gravitly bled it because i was by myself , i just let it bleed while i did other things .such as clean up my mess :doh: i usually use the two person method .
 
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Just so I know for sure, gravity bleeding simply entails letting the air slowly work its way out of the system? In other words, just simply letting it sit? No turning of the slave bleeder? How long do you normally let it set? Sorry for asking so many questions. I just want to make sure the job is done right. Thanks again. :)
 

pbgbottle

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just fill the resevoir on the master crack open the bleeder screw on the slave and let it be .shouldn't take long and out comes the air ,and then see bubbles, and eventually the clean fluid, no bubbles ,something like that :grinpimp:
 
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Durango,Co
I was able to reach the bleeder valve with my left hand and the clutch pedal with my right. Somewhat uncomfortable but it worked.
 
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Clutch master cylinder bleeder screw location

Can't find the bleeder screw on my 85 bj 60 land cruiser. Can anyone help?
 
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Sep 4, 2007
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Pittsburgh, PA
Bleeder screw should be down by your slave cylinder. Follow the lines down to the slave and look for your bleeder screw there.
 
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Not sure if this is the right place for this question, but perhaps someone can direct me. On a 97 fort escort wagon I have replaced both the slave and master clutch cylinders. No fluid coming out of the slave, pump clutch several times and nothing. Provided I have not ruined the Master cylinder... is this when I can open the Slave and hopefully it will gravity bleed itself and then I crack the Master line and let some fluid out and close line again?
Please advice... newbie at this. Thanks
 

Pin_Head

 
 
 
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It is just a cylinder, so the fluid moves back and forth. If you want it to pump fluid, cover the outlet with your finger so the fluid doesn't get sucked back into the cylinder.
 
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The reason to bench bleed is because when the master is empty, and you fill it, as you push the piston , it will allow fluid and air to move around. As you add fluid to replace where it is going, air will enter again. Now, if you have those output tubes going back to the reservoir, eventually you will get equilibrium and all air will be squeezed out and only fluid will remain.

I can suggest a real easy way to do brakes or clutch systems easily by one person. Take a look. Phoenix systems.

Bench bleed.PNG
 
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