Hitachi ZAXIS 120-3 class Operator's Manual page 300

Problem
Coolant Temperature Too Low
Low Engine Oil Pressure
Engine Uses Too Much Oil
Engine Uses Too Much Fuel
Excessive Black or Gray
Exhaust Smoke
TROUBLESHOOTING
ENGINE
Cause
Thermostat
Temperature gauge or sending unit
Engine oil pump or pump drive
Low oil level
Engine oil pressure regulation valve
Plugged oil pump intake screen
Plugged oil filter
Oil leaks
Oil diluted with fuel or coolant
Engine temperature too high
Wrong oil
Wrong oil
Oil leaks
Engine temperature too high
Plugged air cleaner
Internal engine component wear
Plugged or dirty air intake system
Wrong fuel
Fuel injection nozzles
Injection pump out of time
Wrong fuel
Plugged or dirty air intake or exhaust
system
Injection pump out of timing
Injection nozzles dirty or faulty
Basic engine failures
11-3
Solution
See your authorized dealer.
See your authorized dealer.
See your authorized dealer.
Add oil.
See your authorized dealer.
See your authorized dealer.
Install a new oil filter.
Check for leaks.
See your authorized dealer.
Check cooling system.
Drain oil. Use correct oil.
Drain oil. Use correct oil.
Check engine oil drain plug.
Check cooling system.
Clean element or install new element.
See your authorized dealer.
Clean air intake system.
Use correct fuel.
See your authorized dealer.
See your authorized dealer.
Drain tank. Use correct fuel.
Clean air intake and exhaust system.
See your authorized dealer.
See your authorized dealer.
See your authorized dealer.