 On the fuel injected cars a six-plunger pump replaced the previous car's two plunger pump and the injectors were repositioned to give a more direct angle towards the inlet valve heads.The engine cooling fan now had six blades instead of four and incorporated a viscous coupling which activated the fan only when engine speed exceeded 3,000 rpm or the radiator water temperature reached a preset limit.The engine of the 250 S was called M108 (for W108 chassis) and only the 250 SE engine was designated M129.