Yanmar 3YM30 Sevice Manual page 48

2. Inspection and adjustment
(6) Replace the fresh water coolant.
Be sure to replace the fresh water every year. When the long life coolant is used of the specified type,
the replacement period of two years can be obtained.
Use clean soft water and be sure to add the Long Life Coolant Antifreeze (LLC) to the cooling water in
order to prevent rust built up and freezing.
Cooling performance drops when cooling water is contaminated with rust and scale.
Even if antifreeze or antirust is added, the cooling water must be replaced periodically because the
properties of the agent will degenerate.
1) Open the two cocks for fresh water and extract the fresh water.
Note:
One drain cock is behind the belt cover. Remove the belt cover and open the cock.
2) Close the two cocks for fresh water.
Fresh water line
2
Fresh water
pump
Seawater pump
Drain cock for seawater
3) Remove the filler cap of the fresh water cooler by
turning the cap counterclockwise 1/3 of a turn.
4) Pour cooling water slowly into the coolant tank so that air bubbles do not develop. Pour until the
water overflows from the filler port.
Seawater line
2
Drain cock for coolant
If the filler cap is loose, hot steam and water will spout out which may
cause burns.
Coolant tank
Drain cock
for seawater
Drain cock for coolant
Filler cap
Notches
33
Tabs
Coolant tank