Turbo failure? - pics
 

I've got a TO4E that I finally got around to taking apart to inspect after installing a new TO4S last year. I swapped turbos mainly for the bump in power output...however toward the end of the period I used the TO4E it seemed far less responsive and even laggy at times. When I first removed the turbo it had excessive shaft play side to side, virtually none front to back. Now that I have it apart I'm looking for some experienced eyes to look at it and give me your opinion.. not enough lubrication possibly? You'll see in one of the pictures there is a plate that appears damaged from lack of lubrication. On the turbine shaft itself there is a section with a slightly smaller diameter (between the red arrows), is this normal or a symptom of wear?

I know very little about the internals here, first time I have taken one of these apart. In short:

-low mileage when removed, ~10,000 miles
-20w50 used when hot in summer, 10w30 in winter, always fresh
-motor oil pressure is on the low side of spec

When I installed the new TO4S I was suspicious that I was not getting enough oil into the old turbo, so I enlarged my oil restriction a good amount...I figured if it gets too much oil I will know. Seems fine so far, been on for 9 months, no smoking and surprisingly this larger turbo is more responsive than that TO4E was.

Looks like oil starvation, but there's no way to be certain.

The discolouring of the shaft indicates that there were abnormally high temperatures in those areas , this is caused most likely by excessive friction , which would be a symtom of insufficient lubrication . Did you fix your oil pressure problem ? if you didnt , you can look forward to the same thing happening all over again .

Bingo, and do your new turbo a favor and run synthetic oil...

That much oil getting into the turbine section, wasn't the turbo burning a LOT of oil out the exhaust?
Looks like the compression ring on the turbine side was bad?

The blackened thrust washer shows the oil was burning - bad oil or not enough oil.
If you're using good oil, then oil cannot be bad.
If oil pressure was good, then the turbo could've been overspun or abused?
You race this thing?
How much boost?


-Ted

Turbo wasn't really burning oil out of the exhaust at all, I saw some traces at full throttle sometimes but not consistently and never anything that could be called a 'cloud.'

The oil was good, the car isn't driven much and always has fresh/clean dino oil. I'd take the advice above and run synthetic but there is no point for me, I've already got a small leak from the pan that will be fixed when I replace the motor mounts next month, and this is on a stock reman with about 40,000 miles now. When the motor goes I'll run synthetic, I'm not open to switching right now and opening up new leaks. The car is not raced, purely street driven, never anything more than 1bar. Oil pressure is on the low side of spec within the manual but still within spec.

This turbo had an oil restrictor inline with the oil feed, I was under the impression that this thing was oil starved and removed the restrictor with the new installation. The car does not smoke when driven, idles well, tuned with 11:1 A/F at 1 bar with safe timing.

Matt