I had ongoing intermittent problems (over aperiod of about a year) with the clutch hydraulics in my 190E which were worse at higher temperatures. You can do as search for the numerous threads to follow the whole story. This culminated in the clutch pedal intermittently staying on the floor (without dissengaging the clutch).

A new master cylinder fixed the problem. I did not change anything else apart from flushing the old dirty fluid (which I tried prior to eventually replacing the master cylinder). The clutch has been working perfectly since.

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.