WD415 series marine engine, the sister products of WD615 marine engine, is introduction of the advanced European design concepts and therefore the upgraded key basic components are more reliable. The frame balance mechanism with two shafts installed in the crankcase bottom, patented by the Chinese national authority, has thoroughly overcome the problem of big vibration in the four cylinder engines and it is designed to have the character of the six cylinder engines. When designed, it was fully taken into consideration to keep the main components in general use in the WD615 engines, such as the cylinder cover, the piston connecting rod mechanism, the valve mechanism, the gear driving system, the lubricating system, the cooling system, the gear box, the flywheel, the flywheel case and most of the external assembly except the lengthwise components, like body, crankcase, intake and exhaust manifolds, camshaft, crankshaft etc. The sales service is well distributed and it is easy to do the maintenance and repair.