YellowBomberS4

Could this be an issue of no oil to the turbos? They are oil cooled correct? I currently have about 86,500 miles with new stock turbos installed at 54,000 miles I still have the original turbos to be rebuilt at a later date. Any suggestions?

quickaudi:STFA

maybe they are working too hard due to a boost leak? have you pressure tested?

YellowBomberS4

and all the hoses checked. I'm making a consistent 19psi of boost.

Are the turbos oil cooled?

quickaudi:STFA

19 psi on K03s? that peak or hold? if that's hold, holy crap!

YellowBomberS4

No, the 19psi is peak. The sound they are making sounds like metal on metal. Do you know how the turbos stay lubricated? I would assume the bearings would have some kind of lubricant to overcome the heat and wear and tear?

I bought my car in Oct 06 and I'm trying to learn all the inner workings. It's my first forced induction car. Still learning the rules....thanks for the info.

quickaudi:STFA

<ul><li><a href="http://www.s4-mtm.com/images/Audi_S4_engine_english.pdf">S4 self study guide</a></li></ul>

Nich10Solo

I have an '01.5 S4 with the APR 93 oct. chip. I have heard this noise for almost a year. I recently replaced my diverter valves and found some dry rotted vacuum tubing venting vacuum from when I bought the car. I replaced the tubing and haven't heard the sound yet.

So it could be from the turbos working too hard if you are losing boost somewhere.

quickaudi:STFA

exactly

SweetAudi

defintally agree, the tubing on the audi do not last. I had all of my tube replaced and all hoses.

2fst4u2c

a "dentist drill" sound? they're about to blow...