Guenter;
I noticed a slight weep around mine two years ago so I bought a spare. Have not noticed it leaking again so I have never actually done the replacement. Good luck and let us know how it goes. The plastic on these radiators becomes brittle with age and as you have probably read, the neck for the top hose often breaks off. My 1990 300E has 98K on it but has never been used as a daily driver so it has had far fewer heat-up cycles and does not sit outside when not in use. Radiator replacement is on my list but I believe I will wait and do all the things on the top/front of the engine that often need servicing sometime on or after 100K - water pump, short hose at thermostat housing, top timing chain cover leak, etc. I keep a careful check on the radiator but there are many stories of sudden, catastrophic failure around or after 10 yrs/100K that I am concerned.