Hey, my S4 has 81 000 miles on it, theres a couple things I'm wondering about that are getting me worried. When I bring the engine up to around 3800 RPM I begin to hear a rattling noise, and a quiet but noticeable metal on metal sounding noise. I'm also hearing a very high pitched and medium loud whistling or whining noise that matches the speed of the engine. I thought it might be alternator noise coming through the radio but I checked it out and its not. Finally I'm noticing that the shifting is becoming notchier the more I drive it, and I'm starting to find it difficult to downshift into first, even at very low speed. I don't think my turbos have blown as I would defenitely be able to tell, and it doesn't sound like my tranny is gone either, does anyone have any insight into what might be casuing these? All the help you can give is much appreciated, thanks alot.

John

 

On the first issue you mention, I don't know but would guess you may have a loose heatshield or other part of some sort?

On the second issue, kind of hard to tell but I mean, you get the turbo whine so are you sure it's not that your turbos are just getting louder? Also, the sound of the turbos from outside and inside differs... Maybe as of late you've begun to notice the "inside" version of the sound when your windows are rolled up and don't recognize it? One thing you could try is, when you hear the sound put the car in neutral and coast... Do you still hear it? If so, it could be wheelbearings or differential noise...

Your turbos can begin to go bad without you feeling much of a performance hit for a while... Cracks in the casing due to heatsoak or oil starvation can cause warping that affects the rotational stability of the compressor/turbine wheels and/or the shaft. The turbos can still spin to full speed required for any stock boost pressure levels. Longterm they could fail or degrade performance, but it can be a while before you start to notice it. Usually them getting louder can be a sign of the beginnings of failure.

As for shifting, all trannies will get notchier with miles... Also, your clutch may be going. Do keep in mind 1st gears don't use synchros, so down-shifting to first while the car's moving will tend to be difficult (this can be true even on a brand new tranny).

 

im thinking turbo is going. Just a guess though.