Grinding under Boost (w/ no shaft play!)

[mattdev]

Stock '95 Talon TSi AWD

For about the first minute I run my car (cold or not) my turbo makes a pretty loud grinding sound. If I build any boost it makes a weird *whirr* at low rpm's and more of a high pitched grind the more boost I build. It will continue to do this even if the engine is warm but IS worse if it's cold. It will stop almost immediately after I've built full boost and won't do it again, until I start up again!

Sounds like a bad turbo, is what I hear, and it makes sense. BUT when I check for shaft play, there is literally none, and the compressor wheel spins perfectly. So I'm coming to the pro's for help.

My mostly un-educated guess is that it is grinding, somewhere. It stops grinding after a full boost load because that heats it up. The housing expands once its warmed up, and doesn't grind anymore. That's my guess, what's yours?! I also got advice saying it could be something w/ the oil lines, which also makes sense. The car has always been idled after drives though to act as a turbo timer. How would I go about checking oil lines if thats the case.

 

[Turboeagletalon]

sound like oil starvation, that coused the thrust bearings, or bearings to allow the empeller to grind into the compressor houseing.

iv'e seen it before

 

[Pyrice4]

Mine was doing that, I took it apart and the internal heatshield was loose and grinding on the exhaust turbine.