Trouble shooting table 16 Vibrations, droning noise, structure-borne sound D Drive system not or inaccurately aligned D Unsuitable clutch D Unsuitable engine/gearbox mounts D Elastic mounts unequally loaded (height adjustment) D Propeller shaft unbalanced Engine knocks D Engine in cold running phase D Delivery start set incorrectly D Injector needle sticking D High load at low speed D Fuel is slow to ignite D Compression too low Engine is too loud D Intake or exhaust gas pipe leaky D Valve clearance too large D V-belt slipping D Timing gears worn, backlash of teeth too large