Komatsu PC400LC-5 Operation & Maintenance Manual page 176

24. SERVICE PROCEDURE
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When the water is completely clean, stop the engine, close drain
valve 0, wrap the drain plug with seal tape, then close drain plug
0.
Replace the corrosion resistor cartridge and open valves 0.
For details of replacement of the corrosion resistor, see "24.7
EVERY 1000 HOURS SERVICE".
Install the undercover.
Add cooling water until it overflows from the water filler.
To remove the air in the cooling water, run for five minutes at
low idling, then for another five minutes at high idling.
When doing this, leave radiator cap @ off.
After draining off the cooling water of reserve tank 0, clean the
inside of the reserve tank and refill the water between FULL and
LOW level.
Stop the engine, wait for about three minutes, add cooling water
up to near the radiator water filler port, then tighten cap 0.
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