Idle exhaust relief system for outboard motors

Claim 1

An outboard motor comprising: (A) a water-cooled internal combustion engine having an exhaust gas discharge opening; (B) a drive shaft housing mounted below and supporting said engine, said housing forming a chamber closed at the bottom, said chamber having a water outlet positioned to maintain said chamber partially filled with water; (C) a main exhaust housing mounted in said drive shaft housing and having a main exhaust passageway extending downward from said exhaust discharge opening, said main passageway having a submerged outlet for discharging exhaust gas below water; (D) means for introducing water into said chamber; (E) an inlet idle relief passage extending between said main exhaust passageway and said chamber, said inlet idle relief passage positioned entirely above said water outlet; (F) an outlet idle relief passage connected between said chamber and the outside of said drive shaft housing, said outlet relief passage positioned entirely above said water outlet; and wherein said inlet and outlet relief passages are formed between the lower portion of said engine and said main exhaust housing and extend generally horizontally at the top of said chamber and wherein each of said inlet and outlet relief passages includes a reversal in direction.