Yanmar 6SY Series Operation Manual page 110

PERIODIC MAINTENANCE
Internal Cleaning - Heat Exchanger
1. Drain the coolant from the engine and
from the heat exchanger. See Drain,
Flush, and Refill the Engine Coolant on
page 97.
2. Drain the seawater circuit by removing
the cover from the seawater pump and
the connections from the heat
exchanger outlet.
3. Disconnect the coolant pipes from the
charge air cooler. Disconnect the pipe
between the front cover and the heat
exchanger.
4. Remove the connection housing at the
coolant pump inlet together with the
return pipe from the heat exchanger.
5. Remove the thermostat housing cover
and the outlet pipe to the heat
exchanger.
6. Remove the seawater inlet flange from
the heat exchanger.
7. Remove the vent pipe from the coolant
recovery tank.
8. Remove the flange nuts and lift off the
complete heat exchanger assembly.
9. Remove the rear cover and pull out the
cooler element.
IMPORTANT
Under no circumstances should
caustic soda be used to clean the
components.
10.Use paraffin-based engine detergent to
clean the element.
11.Any internal deposits in the pipes can
be removed mechanically using a
round rod.
12.Lubricate and install new a O-ring
(Figure 20, (26)) inside the housing
and install the cooler core.
13.Install the front and rear covers using
new O-rings and gaskets.
102
14.Install the heat exchanger assembly on
the engine. Tighten the flange nuts to
50 N·m
(37 ft-lb).
15.Install the coolant inlet and outlet pipes,
thermostat housing cover, connection
housing, charge air cooler coolant
pipes and thermostat housing.
16.Fill the system with coolant. See Drain,
Flush, and Refill the Engine Coolant on
page 97.
17.Start the engine and check for coolant
leaks. Check the level of the coolant
and fill as necessary.
Flushing Closed Cooling System
A
CAUTION
COOLANT HAZARD!
• Wear eye protection and
rubber gloves when you
handle Long Life engine
coolant. If contact with the
eyes or skin should occur,
flush eyes and wash
immediately with clean water.
• Failure to comply may result in
minor or moderate injury.
CAUTION
NEVER clean the coolant system
with caustic soda. The aluminum
parts may be damaged.
6SY Operation Manual
0000005enMarine
0000175en