Check the small pushrod that connects the pedal to the clutch master cylinder (remove plastic panels by steering column to access) The steel pushrod has a moulded plastic end which shatter when they become brittle. Its a common fault which can be fixed at the roadside. I carry a spare in the cab (only £8 from Mercedes dealer). To change, you need 13mm + 14mm open end spanners. Slacken the bolt with the 13mm spanner to remove the parts including steel barrel & rubber bellows. Transfer the steel barrel to the new pushrod, and refit to pedal. The barrel has an off centre hole through it to give fine adjustment of the clutch "feel". This can be done with the 14mm spanner before finally tightening the bolt with the 13mm spanner. Test drive the truck. If full dis-engagement of the clutch is not achieved, make further adjustment. Hope this helps!
Gruff, January 2014
