Loud grind under boost!

[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?!

 

[oldman]

Remove the intake pipe and check the turbo for shaftplay.

 

[mattdev]

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.

I've already checked for that and it doesn't wobble or slide back and forth, or anything. Unless there's something I don't know about?

 

[PieEyedPiper]

Maybe a problem with the oil lines?

 

[romeen]

What you're describing doesn't really sound like an air leak. However, if it only does it under boost maybe do a boost leak test. It never hurts to do one anyway.

 

[mattdev]

It seems to make boost pretty good, but i do have the stock boost gauge so i couldn't tell you psi. It's hard to explain, it definately sounds like the turbo grinding. How would I go about checking oil lines. And even that, when I bought the car the owner said they always let the car idle for a minute after drives, to let the turbo/oil lines cool. But how would I check it.

 

[mocabro]

i am having the same problem. My turbo spools fine, but as soon as i hit 10 psi there is a alot of vibration noise and no spool up. Did you find out what the problem was with yours ?

 

[bird man]

how does the car sound at idle?

 

[mattdev]

It sounds good to me at idle. It idles at around 650-750 once warmed up. The sound is more of a chatter than a squeal. I'm not really worrying about it that much because I'm getting a new turbo anyway. I'm betting money on the oil lines though like PieEyedPiper said. That makes sense. But I really have no clue.

 

[Apeximprt2nr]

Sounds like your turbo is shot, or soon to be. Does it sound like a siren?
Just because there's no shaft play doesn't mean your turbo is fine.