Komatsu PC220LC -8 Operation & Maintenance Manual page 258

OPERATION
Problem
Abnormal noise generated
(combustion or mechanical)
Main causes
Low-grade fuel being used
Overheating
Damage inside muffler
Excessive valve clearance
TROUBLES AND ACTIONS
Remedy
Change to specified fuel
Refer to "Radiator coolant level
monitor lights up" as above
( Replace muffler)
( Adjust valve clearance)
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