Yanmar 2YM15, Service Manual

Page: 186 / 231

9. Cooling water system
165
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 above 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 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 cooler core.
(2) Remove the pressure cap.
9.4.3 Heat exchanger inspection
Refer to 2.2.6(4).
Filler neck
Cooler core
Gasket
Side cover
Side cover
O-ring
O-ring
Pressure cap
Overflow
pipe