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kyle swart
kyle swart,
Category: Audi
Satisfied Customers: 102
Experience:  Certified Technician at Redding Volkswagen
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My 2009 Audi A4 started making a high humming noise at high

Customer Question

My 2009 Audi A4 started making a high humming noise at high speed (30-60mph). It sounded like it was coming from the transmission. It is related to road speed and not engine speed. The noise does not change with any steering or brake input. It has slowly been getting worse, and is now loud between 20 and 60mph. It sounds like a ring and pinion wearing funny. Every now and then when the car is close to idle and slow speeds, the engine stalls out. Otherwise, the engine works flawlessly. All transmission fluids and diff fluids have been checked. It seems to be trans related, but it hard to pin point. When the car is off the ground, the noise seems to go away a little. Can anybody confirm this is actually failing? Thanks.My car has 97000 miles. My car has an automatic transmission.Please answer only if you are very familiar with these cars. The Audi dealership acts a bit clueless at times, so a bit more confidence than them would be awesome. Thanks.
Submitted: 7 months ago.
Category: Audi
Customer: replied 7 months ago.
The reason I need this confirmed is because I swapped in a used transmission, and the vehicle still makes the same noise. The noise appears to be coming from the front, it does not seem like wheel bearings, so maybe I got a bad transmission.
Expert:  eauto replied 7 months ago.

Hi . Thank you for asking your question on JustAnswer.

Thank you again for trusting us with your problem. John aka eauto

Expert:  eauto replied 7 months ago.

have you run it on a lift to pinpoint the noise?

Customer: replied 7 months ago.
Please let the question go. I already mentioned it didn't make much noise when off the ground. And I need someone who deals with Audi's specifically.
Expert:  kyle swart replied 7 months ago.

is this a quattro or cvt front wheel drive? im wondering if you have a center support bearing failing, but that would only apply to all wheel drive. thank you.

Kyle S.
A.S.E. certified master auto technician
licensed smog technician, test and repair, L-1 advanced engine performance certified
Certified Volkswagen technician, 2003,2004,2013,2014,2015
Volkswagen and Audi technician, Independent, 11 years.

Customer: replied 7 months ago.
It is a Quattro. I thought that might have been the problem, but again, it didn't repeat when the vehicle was lifted. The bearing did seem to have some side to side play in it, but turning it by hand didn't exhibit any noise or roughness. The noise also seems to be coming from the front of the transmission. I've never heard a failed carrier bearing. Could it's sound be directed forward by the sound shielding in the driveline tunnel?It seems like the noise is much louder when the drivetrain has a load on it. At speed, it is a low growing at 20mph and a higher humming at 60mph.
Expert:  kyle swart replied 7 months ago.

if you are not able to duplicate the issue with the vehicle off the ground, that will definatly make it harder to pinpoint. in the past with older vehicles i have had someone else drive and sat in the backseat just to see how much noise is actually toward the rear. there is a tsb for premature wheel bearing failure in the front for this vehicle, but since the sound does not change during turning, rules that out somewhat. center support bearings failing are fairly common, usually on older a4's, and especially on vw touaregs. if you remove the heat shields, lift the vehicle, and run the drivetrain, you may be able to have someone load it up enough to duplicate the sound, while listening to the different components with a stethascope to pinpoint the sound. i like to use a tool called a chassis ear, it lets me clip leads all over the car and run them to a set of headphones that amplifies the sound, then you can click to the specific areas you placed the leads to narrow down the sound.

Customer: replied 7 months ago.
Thanks for the info. I will double check the carrier bearing. When I first installed the new transmission, it drove fine for a couple of weeks, but then it started to do this thing where it would hesitate if I pulled to a stop and drove again immediately without letting the engine settle to idle. Sometimes, if the transition is too quick, the engine completely cuts out. It almost seems like a transmission and engine miscommunication, like the computer is misreading the load of the transmission. No fault codes, and the engine runs perfectly otherwise, which again, makes me think transmission related. Gas mileage also appears to suffer a little. Do you have any experience with symptoms like this?If I end up having to replace the transmission again, do you know if it always requires a reflash of the TCU? It is inside the transmission. My last one did.
Expert:  kyle swart replied 7 months ago.

i have not come across that issue with your model, i have replaced a tcm inside the trans on that model for no communication. if you have the ability to pull fault codes from the tcm that may be helpful, but typically that will throw a "check tcm for errors" code in the ecu as well. if you install a used trans you may have to have the tcm coded to the original coding of the original trans, you can also modify coding to change shift characteristics in the tcm. as far as reflashing, that would usually be for a specific issue, not for a swap.

Expert:  kyle swart replied 7 months ago.

i hope this info helped, thank you.