Symptoms of Turbo Failure1. Low or no boost (Performance
complaints)2. Noise3. Oil leakage4. Poor transient response (i.e
Lazy lag) 5. Blue smoke6. Fault codes 7. Excessive combustion
temperature (i.e. Heat
damaged cylinder components, exhaust manifold and exhaust
pipes)
Causes of turbocharger failure varied
Verifying Performance Complaints Must road test or use
dynamometer to
verify low power complaint.
Intake boost pressure which meets minimum specifications
generally means the turbocharger and engine are performing
satisfactory.
Low Boost = Low-power Boost pressure gauge
No/low fuel = no boost.
Restricted air flow = poor combustion and low-boost
Sources of Noise
Bearings & Leaks
Noise Some turbochargers will create unusual noises during
acceleration.
Warble or (Woofing or barking during deceleration) is commonly
caused by surge when the compressor wheel speed is unable to
correctly move air due to aerodynamics of the housing.
Bearings Coked
Coked bearings caused by hot shut-down.
Causes contact of rotating compressor or turbine wheel with
turbo housings
Bearings
Bearing damage due to hot shut down
Pre-lube Turbo Bearings!
Inspecting Turbo Bearings
Up & Down radial play.
In & Out Axial play
Bearing Inspection
One technique for measuring radial movement
Axial End-Play Measure
Turbine Shaft Damage
Hot shut-down
Compressor Wheel Damage
Note difference between damage caused by hard and soft
objects
Compressor Wheel Damage
Over-speed
Oil leakage
Oil leakage is not acceptable.
Too much idling, High crankcase
blow-by pressure
Worn/damaged seals
Oil leakage 1 All turbos wisp some
oil. Crankcase oil is
drawn into turbochargers of some closed crankcase systems.
