Bleeding Clutch

Clutch, Gearbox, Overdrive, Propshaft, Differential, Drive Shafts, Hubs.
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Firewatcher
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Bleeding Clutch

#1 Post by Firewatcher » Fri Jun 30, 2017 11:30 pm

Perhaps this one should go in the other problems slot - still finding my way round, but it might be of interest to those like me that don't have a suction pump or an understanding wife to help.

The arrangement of pipework from the Master Cylinder to the Slave Cylinder creates an air-pocket, and bleeding the system is almost impossible by pumping the pedal in the usual way.
The fluid viscosity will shift air through the smaller bore brake pipes easily, but not so the larger bore clutch flexible. The fluid will pass below the air-pocket however much you pump the pedal. The simple way to bleed the system manually is with the slave cylinder rested on the front wing and the flexible more or less horizontal. (ie above the discharge pipe from the Master Cylinder)
Open the bleed nipple about one full turn and pump through gently as normal. In that way the air rises easily at each stroke to the slave cylinder and out of the bleed nipple. Gentle pumping and a fully open bleed nipple will not raise enough pressure to push the piston out of the cylinder but will fill the system and allow the air to escape. Lock up the bleed nipple when the bubbles cease, but do not press the clutch pedal again until you have fitted the cylinder to its mounting and connected the push rod.
The position of the piston in the slave while bleeding is not important but I push it right back in. It will find it's own position when refitted after a couple of pedal pumps.
My motor is 1972 and I half expected the flexible pipe to have become brittle, but I put a new slave on in cold weather last winter – no bother except cold fingers.
Pete

tony
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Re: Bleeding Clutch

#2 Post by tony » Sat Jul 01, 2017 3:46 am

You don't need a vacuum pump, just an old syringe to start the flow, then to can go back to normal bleeding.
Tony.
1976 2500 TC.

Lots of bits

1999 BMW Z3.
2003 BMW 525i Touring.
Hopefully not needing too many bits.




.
Hopefully don't need bits !

Firewatcher
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Re: Bleeding Clutch

#3 Post by Firewatcher » Sat Jul 01, 2017 7:29 am

Hi Tony,
I haven't tried that, or using a vac' pump, but this works well without either.
One point I should have mentioned is that the mounting plate needs to be fitted to the slave before connecting the flexible and with this method it is easy to forget.
Pete

JimB
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Re: Bleeding Clutch

#4 Post by JimB » Mon Jul 03, 2017 4:32 pm

Had to do this last week, since the slave had decided to die on me...

A method recommended to me that worked quickly, using gravity bleeding:

- fill new slave with fluid
- hold old, still connected slave aloft
- quickly switch pipe connection to new slave (ensure you've got the bracket too!)
- let new slave on bracket dangle down side of engine
- open bleed nipple, removed screw cap from fluid reservoir and gravity bleed until all the air has spluttered out of the nipple - sorted!

Having a mate topping up the fluid in the reservoir helped. Retaining the original, transparent pipe helped, since you can easily spot the bubbles!

Clifford Pope
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Re: Bleeding Clutch

#5 Post by Clifford Pope » Mon Jul 03, 2017 4:49 pm

I've been lucky then - I've only ever simply opened the bleed nipple and let it run.

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Alan Chatterton
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Bleeding Clutch

#6 Post by Alan Chatterton » Mon Jul 03, 2017 5:06 pm

Another trick to bleed with the slave bolted in place is to open the bleed nipple, have someone SLOWLY press the clutch down, then holding it down undo the clevis pin and push the plunger fully in. Do up the nipple, release pedal and then pump it gently and replace the clevis pin. All this only works if the pipe is on the bottom and the bleed nipple at the top!


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Alan Chatterton

Location; Redditch

DEL 33 1972 Lines Stag Estate Tartan Red

Blog http://vml3m.blogspot.com/

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