EXHAUST PASSAGE STRUCTURE IN OUTBOARD ENGINE SYSTEM

摘要

An exhaust gas passage structure of outboard engine, wherein a split face (481) of an exhaust gas passage forming member (48) is connected to a split face (412) provided at the rear of an oil case (41) sandwiched between an engine block (11) and an extension case (42), a main exhaust gas expansion chamber (e3) and an auxiliary exhaust gas expansion chamber (e7) are formed between the exhaust gas passage forming member (48) and the oil case (41), t he exhaust gas supplied from a first exhaust gas passage (e1) of the oil case (41) is exhausted to a second exhaust gas passage (e5) of the oil case (41) through the main exhaust gas expansion chamber (e3), and a part of the exhau st gas in the main exhaust gas expansion chamber (e3) is exhausted from an exhaust gas outlet (e8) to the air through a communication port (e6) and the auxiliary exhaust gas expansion chamber (e7), whereby the exhaust gas expansion chambers (e3, e7) can be exposed by merely separating the exhaust gas passage forming member (48) from the oil case (41) so that the maintenan ce can be performed without disassembling the oil case (41) and the maintainability can be increased remarkably.