The turbocharger needs lubrication because of the high speeds.

High speeds generate a lot of heat, so proper oil flow and cooling are crucial to extend the turbocharger's life.

What causes most turbocharger failures?

Damage from foreign objects (often in suction)

• Engine fragments, like valve pieces, can hit the turbine wheel. Poor air filter maintenance lets particles (sand, gravel, and other impurities) into the turbo, hitting the compressor wheel's propellers. 
• Damage to the propellers causes turbine imbalance 
• Vibrations worsen over time, leading to severe damage and turbo failure. 
• You can't always inspect a turbine on-site. Ensure the engine is healthy and air filters are quality and in good condition to prevent early damage. 
• If you can inspect the turbine (by removing the intake sleeve), check its condition by moving it up and down. Excessive play or marks on turbine propellers indicate balancing issues. 
• In these situations, overhaul or replacing the turbocharger is recommended to avoid damage to other engine parts. 

Sudden engine shutdown at high RPM and/or without a cooling down period 

It's important to turn off the engine at idle, giving the turbocharger a chance to cool down for 30 to 40 seconds.

This short time allows the cooling system to dissipate heat from the turbine and complete assembly, preventing temperatures > 900°C inside the turbocharger, which can lead to carbonization due to heat transfer. 

A turbocharged engine also needs proper warming up, as fast expansion in a cold engine can crack components due to thermal shock. Respecting warm-up and cool-down times is crucial to avoid early damage. 

Overheating 

Turbocharged engines reach higher temperatures than older naturally aspirated ones → More power means more heat. Excessive heat may rupture or deform the heat shield and turbine housing, causing turbine deformation or component melting/carbonization. Keep engine compartment air passages clear by properly cleaning the radiators and hood grilles. 

Low level or lack of engine oil 

Due to the turbine's high speeds (>100,000 rpm), even a brief lack of lubrication oil can cause severe and costly damage. 

• Skimping on engine oil changes
  A turbocharger isn't sealed, so oil can escape from the bearing housing, letting exhaust gases into the oil. If engine oil isn't changed frequently, combustion deposits from the exhaust can accumulate, contaminating the oil and changing its viscosity. This reduces oil flow within the turbocharger, which can block the turbine. 
• Lubrication circuit issues 
  Check the lubrication system for visible damage or obstruction. 
• Use correct lubrication fittings 
  Ensure lubrication circuit fittings suit the turbocharger to avoid restricting oil supply to the main body bearings. 

Incorrect engine design 

Many turbochargers frequently fail if the engine isn't fit for purpose. This can happen with small engines on very heavy vehicles or small engines with too much horsepower developed. This results in excessive oil pressures that can cause turbine shaft failure. 

Signs of a bad turbocharger

• High engine oil consumption 
  This can stem from worn turbo seals, which let oil enter the intake system. 
• Excessive fuel consumption
  The air/fuel mixture ratio in turbocharged engines is precise. If the turbocharger isn't working well, it can alter this ratio by bringing incorrect airflow, resulting in poor combustion and higher fuel consumption. 
• Bluish smoke
  This bluish exhaust color indicates oil burning. If it comes from the turbocharger, blue smoke will occur at engine idle and during standard operation. 
• Engine oil leaks
  You might find oil leaks near intercooler clamps if the engine's been inactive for a while. If these leaks persist during use, check the turbocharger's condition. 
• Excessive/prolonged turbocharger “whistle”
  The turbocharger generates compressed air, creating a “whistle.” If it's constant or very high-pitched, there's likely a defect in the bearing assembly or turbine. If this occurs, inspect the turbocharger's condition. 
• Loss of power
  Most power in a turbocharged engine comes from the turbocharger. If it's damaged, performance drops significantly. 

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