Lack of Lubrication or Oil Degradation
Causes:
- Low engine oil levels
- Obstructions in oil feed lines
- Build up of burnt oil in center housing
- Excessive Temperature
- Inferior oil quality.
Symptoms:
- Oil leakage
- Noise
- Loss of power
- Excessive smoke
- Excessive oil consumption
Consequences:
- Excessive wear of journal bearings, thrust bearing, and thrust collar.
- An imbalance causing excessive wear to rotating components.
- Wear of sealing surfaces of back plate and thrust collar.
- Piston ring failure or leakage.
Causes:
- Saturated oil filter
- Recycled Oil
- A rebuilt engine with impurities within the oil passages
- Burnt oil from high temperatures
- Residue from incomplete combustion
Symptoms:
- Oil leakage
- Noise
- Loss of power
- Excessive smoke
- Excessive oil consumption
Consequences:
- Scoring and wear of journal bearings
- Scoring and wear of thrust bearing and thrust collar
- Imbalance
- Failed components
Causes:
- Materials ingested into either the compressor, or turbine side of the turbo
- Damage to the compressor side suggests an insufficient/dirty air filtration system, or a damaged air intake tubes.
- Damage to the turbine suggests damage to the engine such as parts of the pistons, or valves.
Symptoms:
- Loss of power
- Noise
- Excessive smoke
Consequences:
- Damage to the wheels.
- Imbalance to the rotating assembly.
- Excessive wear to the rotating assembly.
Causes:
- Frequent turning off the engine at high speed.
- Inferior oil quality.
- High operating temperature.
Symptoms:
- Oil leakage
- Excessive smoke
Consequences:
- Extensive deposits of carbon and shellac in the turbine end seal parts and bearing system.
- In early stages of failure, bearing clearances are decreased by the deposits.
- As the problem continues, the deposits break up, scoring and wearing the bearing bore, journal bearing, and shaft.
Excessive Exhaust Gas Temperature
Causes:
- Engine operation in altitude.
- Incorrect engine air/fuel ratios.
- Malfunctioning exhaust oxygen sensor or other engine control system.
- Malfunctioning EGR valve.
Symptoms:
- Oil leakage
- Noise
- Loss of power
- Excessive smoke
Consequences:
- Erode, distort, or crack the turbine housing.
- Wheels rub the end housings.
- Imbalance to the rotating assembly.
- Thrust bearing / journal bearing collapses.
Surge or Shaft Motion Operation
Causes:
- Engine operation in altitude.
- Application not in accordance to the standards.
- Restricted air admission systems.
- Malfunctioning EGR or PCV valves.
Symptoms:
- Oil leakage
- Noise
- Loss of power
- Excessive smoke
Consequences:
- Damage to the compressor wheels.
- Imbalance to the rotating assembly.
- Thrust bearing / journal bearing collapses.
Causes:
- Low cycle fatigue operation.
- Application not in accordance to the standards.
- Engine operation in altitude.
- Wheel blades design.
Symptoms:
- Oil leakage
- Noise
- Loss of power
- Excessive smoke
Consequences:
- Compressor wheel burst.
- Compressor wheel broken as a ‘slice of pizza’.
- Imbalance to the rotating assembly.
- Excessive wear to the rotating assembly.
Excessive Exhaust Back Pressure
Causes:
- Excessive engine brake operation.
- Restricted exhaust systems.
- Restricted air admission systems.
- Malfunctioning EGR or PCV valves.
Symptoms:
- Oil leakage
- Noise
- Loss of power
- Excessive smoke
Consequences:
- Back of turbine wheel rubbing center housing or heat shield
- Scoring and wear of thrust bearing and thrust collar.
- Imbalance to the rotating assembly.
- Excessive wear to the rotating assembly.
Causes:
- Incorrect engine air/fuel ratios
- Malfunctioning exhaust oxygen sensor or other engine control system.
- Malfunctioning wastegate actuator or its wrong calibration.
- Application not in accordance to the standards.
Symptoms:
- Oil leakage
- Noise
- Loss of power
Consequences:
- Scoring the wheels to the housings.
- Imbalance to the rotating assembly.
- Excessive wear to the rotating assembly.
