Hitachi EX1900-5 Operator's Manual page 210

Check Coolant Level --- daily
CAUTION: Be sure to supply coolant via the res-
ervoir. Don't remove the radiator cap.
Check that the coolant level is between the HIGH and LOW
marks on level gauge (2).
If the coolant level is below the LOW mark, remove cap (1)
and add coolant via the opening.
MAINTENANCE
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1
2
M18C-07-078
M18C-07-079