TroyThunder
Freshman Member

Offline
Greetings fellow British motorists.
I have a conundrum. Over the course of 100 miles or less, and following a complete bleed of the clutch hydraulic system, the pedal will be going soft; it will extend all the way to the floorboard while barely affecting the clutch. Requires multiple pumps to get adequate activation of the clutch system.
At that point, bleeding the system at the slave cylinder, the fluid comes out black (until a fresh supply reaches the bleed screw from the master reservoir.)
Things I've already done: I replaced the master cylinder. I flushed the hydraulic tubing between the master cylinder and the slave cylinder. I double-checked and triple-checked that I am using the correct dot-spec fluid.
Cogitations: does the hydraulic fluid tubing run too close to the header on the engine? And would that kind of heat lead to blackening and disruption of the fluid itself? Answer seems to be "no" to both questions. Could a trace amount of air in the line cause this? Certainly air by itself can cause this soft-pedal effect, but doesn't explain the blackening of the fluid ... does it? (I am making the assumption that the blackening of the fluid coincides with the system failure; presumably a change in fluid viscosity or compressibility. When the system is freshly bled with clean fluid throughout, the system works precisely as it should. No softness. The softness develops over time, presumably as the fluid turns black.)
Does this sound familiar to anyone? Any guidance would be very welcomed.
Cheerio.
I have a conundrum. Over the course of 100 miles or less, and following a complete bleed of the clutch hydraulic system, the pedal will be going soft; it will extend all the way to the floorboard while barely affecting the clutch. Requires multiple pumps to get adequate activation of the clutch system.
At that point, bleeding the system at the slave cylinder, the fluid comes out black (until a fresh supply reaches the bleed screw from the master reservoir.)
Things I've already done: I replaced the master cylinder. I flushed the hydraulic tubing between the master cylinder and the slave cylinder. I double-checked and triple-checked that I am using the correct dot-spec fluid.
Cogitations: does the hydraulic fluid tubing run too close to the header on the engine? And would that kind of heat lead to blackening and disruption of the fluid itself? Answer seems to be "no" to both questions. Could a trace amount of air in the line cause this? Certainly air by itself can cause this soft-pedal effect, but doesn't explain the blackening of the fluid ... does it? (I am making the assumption that the blackening of the fluid coincides with the system failure; presumably a change in fluid viscosity or compressibility. When the system is freshly bled with clean fluid throughout, the system works precisely as it should. No softness. The softness develops over time, presumably as the fluid turns black.)
Does this sound familiar to anyone? Any guidance would be very welcomed.
Cheerio.