Komatsu GD555-5 Operation & Maintenance Manual page 273

SERVICE PROCEDURE
DRAIN WATER FROM FUEL PREFILTER
After the engine is stopped, all parts are at high temperature, so do not drain the water or remove the element cup immediately
after stopping the engine.
Wait for all parts to cool down before starting the operation.
When the engine is running, the engine fuel line is under high-pressure. When draining the water or removing the element cup,
wait for at least 30 seconds after stopping the engine to let the internal pressure go down.
Do not bring any fire or flame close.
If water accumulates in the cup at the bottom of the fuel prefilter,
water separator monitor (1) on the machine monitor lights up.
If the lamp lights up, drain the water from the fuel prefilter as
follows.
1. Open the engine side cover on the left side of the machine.
2. Prepare a container under the drain hose of fuel prefilter (1) to
catch the drained water.
3. Loosen drain plug (2) at the bottom of the fuel prefilter and drain
the water.
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WARNING
MAINTENANCE