COOLANT SYSTEM
Heat Exchanger Components and Functions
12/05
6LY3 Service Manual
7-13
© 2007 Yanmar Marine International
HEAT EXCHANGER
COMPONENTS AND
FUNCTIONS
Heat Exchanger Components
The heat exchanger uses seawater to cool the
engine’s internal coolant system. The inside of the
heat exchanger consists of many small diameter
tubes and baffle plates. The coolant flows through
the maze formed by the baffle plates. Seawater
flows around these tubes and baffles and carries
away the heat of the engine.
Reservoir
There is a reservoir in the upper part of the exhaust
manifold, which serves as the coolant tank. There
is a passageway for the exhaust gases in the
reservoir, which forms a water-cooled exhaust
manifold.
Filler Cap
The filler cap
(Figure 7-11, (3))
on top of the
coolant tank has a pressure valve, which lets off
steam through the overflow pipe when pressure in
the coolant system exceeds the specified value. It
also takes in air from the overflow pipe when
pressure in the coolant system drops below the
normal value.
Figure 7-11
Figure 7-11
1 – Aft Cover
2 – O-Ring
3 – Filler Cap
4 – Seal
5 – Coolant Tube Core
6 – Gasket
7 – Forward Cover
8 – O-Ring
9 – Gasket
Disassembling the Heat Exchanger
WARNING! Allow engine to cool before working
on the heat exchanger.
1. Remove the heat exchanger from the cylinder
head.
2. Remove the forward and aft covers, O-rings,
gaskets and cooler core.
NOTICE: Replace the O-rings and gaskets with
new ones whenever the coolant tube core is
removed.
Heat Exchanger Specifications
No. of Tubes
214
Tube Inner Diameter
5.35 mm
(0.210 in.)
Core Length
687.5 mm
(27.067 in.)
Tube Surface Area
2641 mm
2
(4.10 sq. in.)
0006210
(6)
(5)
(
8
)
(7)
(4)
(
3
)
(2)
(1)
(9)
