[s-cars] Oil and Turbos

[John Cody Forbes]

djdawson2 at aol.com wrote:
> Interesting info...
>
> It seems almost hard to believe that you can get the hot side of a
> turbo glowing red, yet the bearing temp only sees 120C.
>
> It still seems to me that the turbo is where oil failure is most
> likely to occur, just based on years of history looking at
> coked/plugged oil return lines. I don't dispute the facts you've
> presented, it just seems to be a more frequent point of failure...
> one way or the other.

That's easy to explain. While running the circulating coolant and oil keeps 
the bearing cartridge cool, but when you shut the engine off that glowing 
red tubine housing heat soaks into the turbo core. The after-run coolant 
pump only does half the job. The oil is closer to the heat at the rear shaft 
seal and thrust bearing, so the heat soak hits there hard. Only deeper in 
does the coolant passage way suck some heat away from the center core 
section. Voila, baked oil.

-Cody Forbes