Soviet

Jam nut shouldn't be stuck, it can be a slight pain but turning counter clockwise should remove it.

I have read that replacing will stop the leak but I just replace the clutch master cylinder for piece of mind since its cheap. After that, I swap the fluid every oil change for maintenance.

ik2s

Ok thanks. I never really noticed a problem, levels of fluid were ok,I only got the clutch fluid changed to help smooth it out which it really helped (used to sort of 'kangaroo' which seems to have improved) and then noticed the leak when I tried to adjust the clutch rod free play so it could have had a slow leak all along.

in terms if the jam nut, I will try to turn counter clockwise maybe hit it with a lubricant first!

maranelloboy05

Cheap insurance says to just replace the CMC, I think its $75.

jeallen

I rebuilt the clutch master cylinder on my '03 several years ago (I don't believe these parts are available any more), but at the time I ordered an extra CMS to have on hand. So when my '08 started leaking (80K miles), I pulled it knowing I had a spare. Well long story short, the spare had gotten wet and was ruined. Needing to get the car back together quickly for an autocross, I cleaned all the parts and reassembled the unit. It hasn't leaked since (12 months +5k miles).

Observations:
The fluid on these seems to really take a beating, so periodic replacement/flush is a good idea.
Even a small build-up of grunge on the seal can cause a leak. If you do have a leak, you may only need to dissemble and clean the unit to fix the problem.

ik2s

Its all looking promising, I have just checked again after a week and looks like the leak has probably completely stopped. Not 100% sure yet as I had a bit of paper towel to absorb the drip (which is dry) and the master cylinder level remains steady.
+1 to Billmans method of replacing the fluid to fix leak. I will continue to replace the master cylinder every 5k miles to make sure it stays clean.