TURBOCHARGER – INSPECTION AND ANALYSIS TURBINE WHEEL AND SHAFT ASSEMBLY

CONDITION:
Worn turbine wheel blades (360 degrees) (Accompanied by match­ing wear marks on the tur
bine housing I.D.)

CAUSE:
Blade contact against turbine housing due to shaft bearing worn or failed.

RECOMMENDATION:
DO NOT REUSE:
Determine reason for bearing failure. The un
balanced condition can be the result of exces­sive material removal.

CONDITION:
Cracked turbine blade (minor damage shown).

CAUSE:
Foreign debris in exhaust system.

RECOMMENDATION:
DO NOT REUSE:
Further examination of the engine is required to determine the cause of the debris and eliminate it.

CONDITION:
Damaged turbine blades (major damage shown)

CAUSE:
Foreign objects from en­gine, such as pieces of valves or broken piston rings.

RECOMMENDATION:
DO NOT REUSE:
Determine the reason for foreign objects entering the turbocharger be­ fore replacement with a new assembly.

CONDITION:
Excessive oil consumption

CAUSE:
Worn, broken, or missing seal ring

RECOMMENDATION:
DO NOT REUSE:
Replace and examine other components dur­ing rebuild.

CONDITION:
Worn shaft journals

CAUSE:
Contaminated lubricating oil, overspeed, overheat, rotating imbalance or nor­mal wear.

RECOMMENDATION:
DO NOT REUSE:
Determine the cause of contaminated oil, such as fuel dilution or extended oil change intervals.

CONDITION:
Turbine wheel/shaft assembly broken, scored and discolored

CAUSE:
Lack of lubrication to turbine bearing and shaft journal surface.
Note: Exhaust side is more sensitive to lubrication and cooling requirements due to abnormally high operating tempera­tures or turbocharger
overspeed.

RECOMMENDATION:
DO NOT REUSE:
Replace turbine wheel/shaft assembly. If center housing is qualified for reuse, make certain oil passages are clean and unrestricted.

CONDITION:
Turbine wheel back face cracked

CAUSE:
Excessive exhaust back pressure resulting in high exhaust temperature. Ex­amine other engine com­ponents for cause of high exhaust back pressure.

RECOMMENDATION:
DO NOT REUSE:
Check exhaust and in­take restriction according to manufacturer’s specification.

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