Cooling system for marine engine

Abstract

A cooling system particularly suited for use in a small watercraft, which supplies coolant to, and evacuates coolant from, an engine of the watercraft. The engine includes an engine body defining at least one water jacket therein. An engine coolant supply passage desirably routes the coolant into thermal communication with a portion of an exhaust system, such as an exhaust manifold, before supplying the coolant to the water jacket of the engine. When the engine is shut off, coolant is permitted to drain from the water jacket through a drain passage. The drain passage is connected to the coolant supply passage at a position upstream from the exhaust system such that coolant draining from the engine travels in a reverse direction through the supply passage and is drained from the watercraft cooling system. Upon normal operation of the engine, a restriction orifice within the drain passage permits only a relatively small amount of coolant to be supplied to the engine water jacket, without being routed into thermal communication with the exhaust system.