Hi -
Is it possible for air to get caught in the clutch master cylinder?

I had a leaky clutch slave cylinder and have a spongy clutch after replacing it. I fully compressed the slave cylinder to compress but it still feels like there is air in the line. (The fluid level dropped too the point that air was getting pushed through during pressure bleeding. We added more fluid to correct.) I don't see any bubbles coming out of the slave cylinder.

Thanks,

 

This might help you a bit, specifically regarding installing a clutch slave cylinder:

"Installing the new slave cylinder is a bit tricky. In order to bleed the system, you will need to compress the slave cylinder fully prior to hooking up the hydraulic line. The slave cylinder is normally compressed by the huge amount of force on the clutch pressure plate. The pressure plate exerts force on the throwout arm, which in turn presses against the slave cylinder’s piston. Now, when you press the clutch pedal, the hydraulic pressure exerted against the throwout arm is greater than the force of the pressure plate holding it back. Thus, the pressure plate moves, disengages the clutch plate from the flywheel of the engine and allows you to shift the gears."

http://www.pelicanparts.com/techarti...eplacement.htm

-Jorge

 

We just got done doing a slave swap a few weeks ago and went through hell getting it to work correctly. We finally found some info from a Mini tech in GA that did the trick. We bled normally just like doing brakes to get the air out. We compressed the slave as most directions advise but be very careful as you can over compress and damage the slave internals. Once you get it working fairly good the magic step comes in play.
Depress the clutch pedal fully and measure the distance from the pedal face to the metal seat rail bolted to the floor. Now cut a stick and wedge it in place to keep the pedal fully depressed. Leave it in place overnight. Remove the stick and your pedal will be perfect once again.
We didn't believe this would work but we have done it twice now with perfect results each time. Using this trick we have saved untold hours in bleeding the slave.
I don't the name of the Mini tech that gave this info out but I need to find the guy and buy him a beer or two.
I passed this info to the tech at my local dealer, who by the way said I was in for a treat when I asked him for directions on bleeding. He has sinced used the trick and it has irked for him every time.

Good luck,

Tom in PA

 

Hmm, that sounds interesting.

I followed the bleed procedure as outlined in the Bentley manual (compress the slave cylinder and bleed with a pressure bleeder) and finally got the pedal to be responsive and not spongy, but I also replaced my clutch recently, and ever since the pedal feels a bit spongy and the clutch engagement point is almost at the floor.


I'll try the master cylinder compression technique. I can see the logic here. There is no bleed valve on the master cylinder but by compressing it, it should allow any remaining bubbles to work their way back up the reservoir supply line and back into the reservoir...