Komatsu PC118MR-8 Operation And Maintenance Manual page 368

MAINTENANCE PROCEDURES
4. Check that the cooling water temperature has decreased
enough to allow the radiator cap (4) to be unscrewed to the
stop in order to relieve the pressure.
5. Press the radiator cap (4), unscrew until it stops and
remove it.
6. Open the radiator drain valve (5), remove the drain plug (6)
on the engine block and let the fluid flow out, gathering it in
a container with suitable capacity.
7. Close the discharge valve (5), replace the cap (6) on the
engine block and fill the radiator with clean water. Start the
engine and let it idle.
When the temperature rises above 90° C leave the engine
running for 10 minutes.
8. Stop the engine, then open the discharge valve (5) and
remove the drain plug (6) to drain the water.
9. Close the discharge valve (5) and the plug (6) and fill the
radiator with new coolant.
10. Start the engine and let it run at high idling speed for 5
minutes; check the level again and top up before putting
back the upper cap (1).
11. Drain the liquid from the buffer tank (7), clean the inside.
12. Fill the tank (7) until reaching the maximum level (FULL).
13. Refit the covers and close the hood.
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MAINTENANCE