Battle-Cat

Hello!

I own a 2011 A4 Avant Quattro. Since the last year, there's a overworked fan noise coming from the rear right of my car (possibly exhaust) during the following conditions:
- outside temperature below +/- 70º F.
- RPM around 1.9K
- low gear 2-3

The sound gets worse as the temperature drops, I live in the San Francisco Bay Area so it doesn't drop that badly, but during the mid winter the sound would persists throughout my commute.
I can describe the sound as:
- a computer fan working too hard
- the sound of drill hitting something hard and is over-torquing

I have searched the net and read many threads but couldn't find anything about it. My car is under extended warranty and have been brought to Audi service center, but it never makes the sound when I take it on a road test with a mechanic. They never found anything during visual inspections, I think they are reluctant to dig further without and an engine light on.

Thank you for reading this, any suggestions?

Battle-Cat

Where is the power steering pump located on a 2011 Audi A4 Avant?
A friend of mine who was riding passenger in my car told me the noise was coming from the front right of the car. It sounded like whine.

treilley

Does the sound go away if you shift to neutral and let the rpms fall? Can you duplicate the sounds when sitting still and revving the engine to 1900rpm? Basically, does the sound change in frequency or volume with engine speed or vehicle speed?

- Bad speaker with engine interference(happens when stopped revving to 1900rpm)
- RR wheel bearing?(happens while moving in N)

Battle-Cat

Hi treilley,

the noise happens only in gear. So the only visible thing on right front side under the hood, is a black box with a tube that leads to the front grill, is that the air intake? As you can see, my car knowledge is vast... The noise does sound like an air noise.

treilley

Your original post states RR of vehicle.

If indeed RF then it could just be normal intake noise. Yes, that tube is the intake. Black box is the air filter housing.

My A4 has the Injen aftermarket intake and will make a whiny whistling sound at certain rpms.

Remove the air filter, check air intake and make sure nothing is blocking.

Battle-Cat

When driving by myself, the noise seems to be coming from the Rear, but my friend who was riding on the passenger was pretty sure it came from the Front.

I'll take a look at the air filter. I'm trying to see what the relation ship with the external temperature and the noise, it only shows during "cold" weather here in the San Francisco bay area, could it be some kinda of rubber part (I know rubber reacts to temperature). One thing for sure, is the sound is happening more frequently compare to last Fall/Winter, so it is failing...