Coolant System Components And Functions - Yanmar 6LY3 series Service Manual

COOLANT SYSTEM
COOLANT SYSTEM
COMPONENTS AND
FUNCTIONS
The coolant system is an indirect seawater-cooled,
coolant-circulation type. The cylinders, cylinder
head, turbocharger and exhaust manifold are
cooled with coolant. The heat exchanger, oil cooler
and intercooler are cooled with seawater.
Seawater is pumped in by the seawater pump and
goes to the heat exchanger where it cools the
coolant. It is sent to the intercooler and then the oil
cooler. After going to the marine gear oil cooler,
seawater is sent to the mixing elbow and
discharged from the boat with the exhaust gas.
Coolant is pumped by the coolant pump from the
coolant tank to the cylinder jacket to cool the
cylinders, turbocharger and then the cylinder head.
The coolant pump body also serves as a discharge
passageway (line) at the cylinder head outlet and is
fitted with a thermostat.
7-4

Coolant System Components and Functions

The thermostat is closed when the coolant
temperature is low, immediately after the engine is
started and during low load operation. Then the
coolant flows to the coolant pump inlet, and is
circulated inside the engine by passing the heat
exchanger.
When the temperature of the coolant rises, the
thermostat opens, coolant flows to the heat
exchanger and is cooled by the seawater in the
tubes as it flows through the coolant pipe. The
temperature of the coolant is kept within a constant
range by the thermostat.
© 2007 Yanmar Marine International
6LY3 Service Manual