It seems that if the debris can get past the seal, then the fluid could get past the seal in the opposite direction and cause a leak. Are you sure that the material found in the bottom of the master cylinder is not sludge caused by moisture contamination?

 

All I personally know is that my C5 had the debris/sludge in the MC and others have experienced the same thing. When this occurred on my 12 year old/low mileage C5--the fluid was very dark-- more than the brake MC. And the sludge removal seemed to have improved my clutch.

And we are discussing minute amounts of dust over a large period of time.And it is possible if there is minute leakage at the slave cylinder--it would go unnoticed as the clutch disc wears and the clutch MC fluid level changes .

The etiology of why and how this debris is in the MC isn't as important as addressing the OP's original stated problem .

Though it is thought by some that this debris/dust will cause the slave cylinder to leak over time because it may abrade the seals.I suspect that the type of usage the clutch has experienced--will determine the amount of sludge in the MC. Some of us are easier on a clutch than others and will have less wear--and less resultant debris/sludge.


People believe that the debris removal improves the clutch action. I am suggesting that the OP try removing anything found in his MC and do it several times and see if his clutch improves. It is easier than bleeding the slave cylinder.

Let's not argue---if you are not convinced this is a possible way to correct the OP's issue--fine--you can try something more difficult and expensive when and if you have a similar problem.

 

Not arguing. Just trying to understand cause & effect of the problem. I know manufacturers recommend flushing & replacing brake fluid every two years. Is there a similar requirement for hydraulic clutches?

 

Brake fluid is hygroscopic. That means it can attract and hold particulate in its surrounding environment and worst of all water. The sludge at the bottom of the mc is likely this.

Keep the system sealed. If your bleeding the system, keep the MC sealed as much as possible. And don't use the big jug of brake fluid, buy the small ones and throw away what's left over. Those plastic caps on the big jugs don't seal as good as you think and when you set it on your shelf, moisture is seeping in.

Mike

 

I had a similar problem with my '98. I did a shifter realignment and changed the transmission fluid (M6 uses Dextron) and that solved it. I sold the car with 91K miles and never a problem. Here is a how to link;
http://www.rpmtransmission.mobi/file...adjustment.pdf