It is the 601 engine 1994 in the T1 box with 210,000 KM the clacked. Before about 50,000Km the chain was changed due to length in MB transporter workshop. About 20,000 km later I heard for the first time a quiet clacking which however always when then Moror was warm disappeared. In addition it did not occur regularly and sounded like coming from the injection pump. Also it sounded like the sound of the injection pume if one would strengthen it. Naturally also in the flick of the injection. 15,000 KM later was there But absolutely irregular, sometimes louder, quieter, not at all. There was no regularity to be found. Sometimes 500KM no clacking and then suddenly again and disappeared again. It also came short and disappeared again, but there was more than 50% of the operating time to be heard. Then finally the clacking was present at the MB transporter workshop and the noise specialist, who also recognized the chain length at the sound (wa r then confirmed, since the vehicle was called back because of bad chain but never changed) said after some engine tests, that the camshaft on the hydro beats because it has a defective valve. Repair is not mandatory but costs approx.250€ !!! To this day the clacking is more often 80% operating time, even at top speed and sometimes even louder. L.Moly Hydropulse oil brings noise reduction but not for a long time, the engine probably burns this oil r Now I drive with 2TÖL and the engine is quieter and the clacking for the ear all the louder and I want to have the clacking away. I already read that it can also be the head seal. How can I invest what is now defective? Can one perhaps see the leak oil in the chain casing? Or something else? Would I be very angry if I changed the hydros and it clacks further.