Bleeding You Hydraulic Clutch System: How to Do it with Style

Your hydraulic clutch system is a wonderful smoothly operating method of engaging and disengaging the engine from the transmission. Most of the time. However, should you ever find the need to expel air from this hydraulic line...you may in for a long tedious experience.

I recently had to replace the master cylinder of my hydraulic clutch system. This was easily done as it comprised only one fluid line..and two bolts. Once the new master cylinder was mounted however, I found that air had gotten into the line..and adamantly refused to leave.

I undertook all of the common methods of removing this air but to no avail. I tried bleeding the system from the slave cylinder. I tried opening and closing the bleeder valve at the slave cylinder while someone pumped the clutch pedal for me. I tried using a vacuum pump to pull fluid and air out of the system. Each and every effort failed.

Air in a hydraulic line is a for certain way to insure that the hydraulic function will NOT occur. Air is compressible. A fluid is not. So when you place you foot on a brake pedal, or a clutch pedal and apply pressure, the non-compressing nature of that fluid, allows that fluid to behave as if there was an actual physical link in action. As an example..if there was a steel bar attached to your brake pedal..that would activate the brakes when you stepped on the brake pedal...that bar would be an actual, physical, material link..from pedal to brake shoe. A hydraulic line is very similar. When you step on the pedal..there is a force applied to the brakes..by the non compressing nature of the fluid..within that line...the force applied on that pedal, is instantly applied at the other end of that line...unless..there is air trapped within that line. The air will compress..stealing energy..and will not transmit the force applied.