9. Cooling Water System
153
9.4 Heat Exchanger
9.4.1 Heat exchanger construction
The heat exchanger cools the hot fresh water, that has
cooled the inside of the engine, with seawater.
The cooler core consists of many small diameter tubes,
baffle plates and tube cover.
The seawater flows through the maze formed by the
baffle plates.
There is a reservoir below the cooler core, which serves
as the fresh water tank. There is an exhaust gas
passageway in the reservoir, which forms a water
cooled exhaust manifold.
The pressure cap (filler cap) on top of the heat
exchanger has a pressure valve, which lets off steam
through the overflow pipe when pressure in the fresh
water system exceeds the specified value. It also takes
in air from the overflow pipe when pressure in the fresh
water system drops below the normal value.
9.4.2 Specifications of heat exchanger
9.4.3 Disassembly and reassembly of the heat exchanger
(1) Remove the side covers on both sides of the cooler core and take out the cooler core
and O-ring(s).
NOTE: Replace the O-ring(s) when you have removed the cooling pipe.
(2) Remove the pressure cap
NOTE: Don’t remove the filler neck.
9.4.4 Heat exchanger inspection
Refer to 2.2.5(4).
MODEL
UNIT
3JH4E
Tube dia.
mm
Ø6/Ø5 x 54
Tube surface area
m
2
0.193
Fresh water flow
L/hr
3300
Sea water flow
L/hr
3080
Fresh water velocity
m/s
0.99
Sea water velocity
m/s
1.61
Filler neck
Cooler core
Gasket
Side cover
Side cover
O-ring
O-ring
Pressure cap
Overflow
pipe