I had recently noticed slight smoke in the engine of my BMW 640d, which was probably caused by diesel drops in the engine compartment. I then brought the vehicle to the workshop, where it was found that a valve cover seal is leaking and that possibly one or more injectors are leaking. Therefore, the engine was cleaned several times in the workshop according to telephone information and tested again and again. After the 5th test drive a loud clacker was also heard. This was not the case when driving to the workshop or before. According to the owner of the workshop suspicion of conrod bearing damage (also in the 1st calculation ) or injectors. I also listened to the clackering and ordered the workshop to look at the injectors. 2 days later, the owner of the workshop calls me and informs me that, despite the considerable engine noise, he has driven the vehicle again and that it has caused total damage to the engine, i.e. piston eater. However, he shows any blame for the engine damage, this would be my problem as a customer.