Kohler APM402, Operation

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102 TP-6694 9/20
3.9 Cooling System
The cooling system maintenance information applies to radiator-cooled models which have a radiator with a pressure cap and
coolant recovery tank.
WARNING
Hot coolant and steam.
Can cause severe injury or death.
Before removing the pressure cap, stop the generator set and allow it to cool. Then loosen
the pressure cap to relieve pressure. Fill system before starting unit.
Allow the engine to cool. Release pressure from the cooling system before removing the pressure cap. To release pressure,
cover the pressure cap with a thick cloth and then slowly turn the cap counterclockwise to the first stop. Remove the cap after
pressure has been completely released and the engine has cooled. Check the coolant level at the tank if the generator set has
a coolant recovery tank.
Note:
Engine damage. Bleed the air from the cooling system to prevent overheating and subsequent engine damage.
Note:
Block heater damage. The block heater will fail if the energized heater element is not immersed in coolant. Fill the cooling
system before turning on the block heater. Run the engine until it is warm, and refill the radiator to purge the air from the system
before energizing the block heater.
3.9.1 Coolant Level Check
Check the coolant level in the coolant recovery tank (if equipped). Maintain the coolant level between the high and low marks .
Use the site glass on the radiator to check the coolant level.
Note:
Periodically check the coolant level by removing the pressure cap. Do not rely solely on the level in the coolant recovery tank (if
equipped). Add fresh coolant until the level is just below the overflow tube opening of the filler neck.
3.9.2 Cooling System Component Inspection
To prevent generator set shutdown or damage caused by overheating:

Keep the cooling air inlets clean and unobstructed.

Inspect the radiator’s exterior for obstructions. Remove dirt and foreign material using a soft brush or cloth to avoid damaging
the radiator fins.

Check the hoses and connections for leaks. Replace any cracked, frayed, or spongy hoses.

Check the condition and tension of the radiator fan and water pump belt(s). Follow the belt tension procedure in this manual
and/or the engine operation manual.

Check the pressure cap seal and replace a cracked or deteriorated cap. Remove dirt and other debris from the pressure
cap and filler neck. The pressure cap raises the boiling point of the coolant, enabling higher operating temperatures. Replace
a leaking pressure cap with one rated for the same pressure. The pressure cap rating usually appears on the pressure cap.