[Mgs] MGB Clutch Problem

Barney Gaylord barneymg at mgaguru.com
Fri Aug 24 11:54:35 MDT 2007


At 07:09 PM 8/23/2007 -0700, danny varnado wrote:
>.... the clutch will start to bleed down and engage while I hold the 
>pedal down.  ....

Regardless of anything else, this indicates that fluid is leaking in 
the master cylinder internally past the piston seals back into the 
reservoir.  You will need to rebuild or replace the master cylinder.

To everyone who thinks the bleed nipple on the bottom of the slave 
cylinder is a problem, it isn't.  When a new slave cylinder is 
shipped the bleed nipple may be installed in the end port to make the 
package smaller.  In this case you need to move the bleed nipple to 
the side port, as the end port is for the hose connection.  You do 
not have to dismount the slave cylinder to bleed out the air, but the 
bleed nipple does have to be on the side, not on the end.

When installed the bleed nipple will appear to be on the side of the 
slave cylinder pointing downward at about 30 degree angle from 
horizontal.  This is NOT a problem.  Internally the drill hole for 
the port is tangent to the cylinder bore and intersects the internal 
cavity near the top.  This does allow for bleeding out the air before 
the fluid, so it does not trap air in the slave cylinder.  See 
cylinder internal picture here: http://mgaguru.com/mgtech/hydraulics/ht106.htm

If you dismount the slave cylinder and position it horizontally with 
the bleed nipple pointing straight up, the internal poat will be 
nearly half way down the side of the cylinder wall, and that could 
trap air in the cylinder.  If you hang the cylinder vertical with the 
hose on top, then the bleed port will be at (or near) the top 
regardless of rotation of the cylinder.

Reverse bleeding from bottom up does seem to work.  Pressure bleeding 
from top down also works well.  The trick is to move fluid through 
the line fast enough to carry any air along with it out the bleed 
port.  If you do short bleed strokes with long pauses in between the 
air can bubble back up the line and may never be expelled.

For bleeding with no special tools, open the bleed nipple and place a 
finger over the end to serve as a check valve.  Have a helper do 
several strokes of the pedal in quick succession, then hold the pedal 
down while you close the bleed nipple.  You can minimize the spray 
mess by putting a small hose on the nipple, putting your finger over 
the end of the hose, and holsing it in a catch vessle during the process.


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