My engine has now run 412 000 km (I am a first buyer) Once the ZKD had to be renewed, because the head had to be removed due to two broken glow plugs. The valve shaft seals were also immediately renewed and the valves were regrinded (291 000 km). Now I want to have the chain checked for length and if necessary let chain tensioners and sliding rails change with you. A lengthing should already be present at the running performance. Does anyone have special experience with this engine? My screwdriver wants to install an Iwis chain and says that it was original equipment for this engine.