Engine Cooling System - Centurion Ri257 Owner's Manual

Controls, Features and Options

ENGINE COOLING SYSTEM

Marine inboard engines may be cooled in different ways. Depending on your
engine application, an open or self-contained cooling system may be used.
An open cooling system uses raw water (seawater) to cool the engine and/or drive
system. A continuous flow of raw water is used to transfer heat from the engine
and drive cooling passages and is then returned to the sea. A seacock and raw
water pickup on the hull allow water into the engine, and a pump then circulates
the water to cool the engine.
Seacock
TYPICAL SEACOCK AND STRAINER
STRAINER
OPEN
CLOSED
SEACOCK
INCOMING RAW
WATER
KC-0189-A
Figure 8-18
A self-contained/closed cooling system uses raw water to cool the engine and/or
drive system through the use of a heat exchanger. A continuous flow of raw water
is used to transfer heat from the heat exchanger to cool the engine and drive
coolant. The engine cooling passages and heat exchanger passages are
self-contained/closed, similar to an automotive cooling system. Heat is transferred
from the engine and drive to the coolant and circulated through the heat
exchanger in the closed system. A separate raw water passage in the heat
exchanger is used to transfer heat from the self-contained engine coolant to the
raw water. The raw water is then returned to the sea.
Raw water intakes on the hull use a seacock to provide manual shutoff if a leak
occurs. Periodically inspect the raw water intake screen (if equipped) and clear it
of debris that could obstruct water flow into the engine. NOTICE: Keep seacocks
closed during periods of inactivity. A downstream hose failure could flood the boat
if the seacock is left open. Open seacocks only when necessary.
8-19