In these images, you can see that the back of the compressor wheel has become rippled and pitted, which are early signs of damage caused by overspeeding.
Overspeeding damage like this occurs when a vehicle’s engine causes the turbo to spin faster than it is designed to. This excessive speed causes the materials of the compressor wheel to begin to flex, and spin out of balance, causing warping, metal fatigue and premature bearing failure.
There are several causes of overspeeding, including ECU faults and remapping issues and leaks in the intercooler system.
Whilst this ‘rippling’ might not look like much, a compressor wheel in this state is beyond economical repair, and the best course of action is to have it replaced with a new one.