Komatsu PC300LC-8 Operation & Maintenance Manual page 170

OPERATION
Adjustment of Drain Valve
If drain valve (4) is stiff, coat the O-ring portion of the drain valve with grease to make the movement smooth.
1. Turn the valve (6) at the bottom of the fuel tank to the CLOSE
position (S).
2. Set the container to catch the fuel under the pre-filter cartridge.
3. Loosen drain valve (4), then drain all the water and sediment in
the transparent cap (2) and also the fuel accumulated in filter
cartridge (1).
4. Check that nothing more comes out from drain hose (3), then
remove drain valve (4).
5. Coat O-ring portion (7) with a suitable amount of grease.
When doing this, be careful not to let the grease get stuck to the
drain valve water drain port (8) or drain valve thread (9).
6. Tighten drain valve (4) by hand until it contacts the bottom of transparent cap (2).
7. Remove the fuel container.
8. Turn the valve (6) at the bottom of the fuel tank to the OPEN position (O).
MACHINE OPERATIONS AND CONTROLS
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