COMMON INDICATORS AND CAUSES:
With all the variations in diesel engine design running in equipment today, it’s almost impossible to make a complete list of the symptoms and causes you may encounter. This tech bulletin is not meant to be considered as a complete list of those indicators and/or their causes. However, hopefully, it will provide you with a general list of possible causes related to some of the more common complaints you may hear concerning diesel engines. Indicators and causes vary between engine models, applications, and design. As you review the list below, you will most likely be able to add additional information based from your own experiences.
Problem Indicators: Excess black smoke during full load (unburnt fuel)
Possible Causes:
- Faulty electronic sensor(s)
- Fuel ratio control setting
- Intake or exhaust restriction (plugged air cleaner?)
- Lugging
- Overfueling or overloading
- Valve adjustment
- Failing turbocharger
Problem Indicator: Blue smoke (oil consumption)
Possible Causes:
- Oil leaks
- High oil levels resulting from other problems
- General engine wear due to hours of operation
Problem Indicator: White Smoke (water in combustion chamber or unburnt fuel at start up)
Possible Causes:
- Faulty electronic sensor(s)
- Cold ambient air temperature
- Leaking head gasket
- Cracked head and/or liners
- Faulty injector(s)
- Incorrect starting procedure
- Quality of the fuel
Problem Indicator: Increased oil consumption or Blow-by
Possible Causes:
- Oil leaks
- Quality and type of oil
- Air compressor
- Normal engine wear
- Worn or broken rings/liners
- Worn turbocharger seals
- Worn valve guides
- Overloading
- Prolonged idling
Problem Indicator: Unusual noises
Possible Causes:
- Malfunctioning fuel nozzle/injectors
- Worn engine components
- Turbocharger
- Too much valve lash
Problem Indicator: Lack of power
Possible Causes:
- Faulty electronic sensor(s)
- Intake or exhaust restriction (plugged air cleaner?)
- Fuel restriction
- Fuel components
- Governor settings
- Transmission, torque converter, or other components
- Fuel quality
Problem Indicator: Increased fuel consumption
Possible Causes:
- Fuel leak
- Faulty electronic sensor(s)
- Intake or exhaust restriction (plugged air cleaner?)
- Turbocharger
- Fuel components
- Operator
Problem Indicator: Overheating
Possible Causes:
- Faulty electronic sensor(s)
- Plugged radiator
- Incorrect adjustment or worn belts/pulleys
- Low coolant level
- Malfunctioning temperature regulators
- Failing water pump
- Operator
Problem Indicator: Hard starting
Possible Causes:
- Worn fuel components
- Faulty electronic sensor(s)
- Improper starting technique
- Fuel quality
- Low cranking speed
Problem Indicator: Oil level over full
Possible Causes:
- Coolant or fuel dilution of oil
- Over filling
Debris in oil filters is never a good sign!
In most cases a good maintenance program will prevent or identify problems before they progress into something major. Qualified technicians, with the correct tools, are essential in diagnosing and repairing problems correctly.
