Turbocharger Failures, Effects, and Causes

Turbochargers are used in internal combustion engines to optimize combustion and increase engine performance. A turbocharger can increase the power output of a naturally aspirated engine by 15-25%. The turbo is driven by exhaust gases, so unlike a belt-driven supercharger, it does not draw power from the engine. On the other hand, a turbocharger does not provide extra boost until the throttle valve opens and exhaust flow increases. Once it starts spinning, it pushes more air into the engine. Turbos can spin at speeds of 200,000 rpm or higher, but it takes a few seconds to reach these speeds.

At the core of a turbocharger are the air intake wheel (compressor side), the exhaust gas intake wheel (turbine side), and the shaft connecting them (see Image 1, 1.1). Depending on their design and function, turbos have a limited lifespan during engine operation. In practice, there are various risk factors that can cause premature turbo failure. A successful repair and overhaul process requires identifying the root cause of the failure. Otherwise, a newly installed turbo may begin malfunctioning and failing in a short time. This brochure explains some common problems and possible root causes to assist you.

Improper or Insufficient Lubrication Conditions:
Insufficient lubrication is one of the most important factors causing turbo failures. When lubrication conditions deteriorate, turbo failure is inevitable. The main reason is their operation at very high speeds.

Effects:

• Damage to the turbo bearing can cause the compressor and turbine wheels to collide with the turbo housing. This can be detected if there are wear marks on the turbo housing and deformation on the wheels.

• If the turbo shaft rotates improperly due to contaminated lubrication, the turbo’s intake pressure decreases, leading to reduced engine performance.

• Insufficient turbo air intake may cause black smoke to be emitted from the exhaust because insufficient air reaches the combustion chamber relative to the fuel supplied. This indicates an overly rich air-fuel mixture.

• When lubrication is insufficient, heat generated by friction can cause discoloration on the surface between the turbo shaft and bearing. If the temperature reaches critical levels, the bearing material may begin to stick to the shaft surface.