Hello,

You have a w126 with manual transmission? What engine is installed. Is this a Euro car.

The manual clutch stuff on the early mercedes shares the brake res., for fluid and has a master cylinder next to the pedals [have to remove the cover under the drivers position] and the a slave cylinder next to the bell housing.

You could have a problem with the slave or master, both can fail. I have replaced both on my Euro 300d. Easy to replace, the master anyway, but a ***** to get the air out of the system. You may just have air in the system?

brian