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      11-14-2012, 11:08 PM   #31
First Lieutenant

Drives: 2007 335I
Join Date: Mar 2012
Location: Turbotown

iTrader: (0)

Originally Posted by Vargasturbotech View Post
Turbos should not I repeat not make that noise, a whistle is 100% normal and with less restrictive exhaust you will hear it more. With a siren or as its called turbo howl your turbos are well on there way to going out. The noise is caused by excessive play in the center section, either in the journal bearings radial play or in the thrust axial play, usually its a combo of both. This allows defelction under boost as the exhaust imparts force on the turbine wheel, the excessive play allows the compressor wheel to actually slightly contact the compressor housing causing metal to metal contact and this noise. Once this occurs it actually starts to machine away the blades of the compressor wheel a little at a time and it will eventually throw itself out of balance, take out the piston rings and everything else with it, and you will start smoking badly. Another thing I have seen with stock turbos is, the turbine side piston ring allowed excessive oil to escape past, which gets under the heat shield and from the extreme heat turns into carbon and as this builds up under the heat shield it pushes the back of the heat shield into the back of the turbine wheel, this can also cause this noise with the same results. Bottom line, turbos are on the way out, next thing in the time line is smoke. Hope this helps.

What I don't get is how my turbos sound like that with less than 3k on them. I got new turbos under warranty for wastegate issues. I have spent the past month trouble shooting, trying to make absolutely sure the car didn't have some other problem. I just got my DME flashed back to stock, and I will drive it stock through thanksgiving and then I plan to take it in and ask WTF?? I'm thinking they were bad parts from the get-go OR there was an install error.( I actually went back the day after because the car seemed to oscilate- not accelerate smoothly as I left the dealer- they said it was fine) I was afraid that after going back to stock they would quiet down some and then the dealer would tell me nothing is wrong. Happily, the car is now 100% OEM and still sound the same. Combine the sound with boost issues and random limp modes i've been getting....we'll see if the third time is a charm

I will keep the car stock until spring so that if this next set is messed up- I won't have to go through this ordeal AGAIN.

Last edited by KaiserN54; 11-14-2012 at 11:13 PM.