I need help diagnosing the latest problem with my A6. I enjoy my car tremendously until it has a problem. Any and all input will be appreciated. Here's the background:
2003 A6 2.7t quatto 6 speed manual transmission
out of the blue, couple of weeks ago the car front wheels begin with a vibrating/grinding sound. I first thought it was the same sound as when the bearings were bad. I just had both front bearings replaced in August this year. So I was going to bring it back to same place to revisit issue. Sound gets louder with increased speed. Sound is not related to whether car is in gear or not. Breaks make no sounds. Today a loud "clank" is repeatedly heard. Random "clank" and "clanks" when driving straight or turning.
I became alarmed and pulled into a mechanic's shop for consultation. He has done some work for me in past and is very good with german/european cars.
He took for a test drive and said it sounded like bearing was very bad and wheel was loose. He immediately put it up for me and check wheels but they were not loose. And he then started to think it was not the bearings. He did say the CV joints were not good, but that had nothing to do with the sounds. Took it on a second test drive and concluded that I need a second opinion but his thoughts were that it could be the differential.

Other suggestions from other mechanics I've talk to today:
4wheel drive unit / transfer case

I would appreciate any thoughts and how to best resolve this problem. I don't feel safe driving it like this so I have to get a solution!

 

Would drain & fill the liquid on 3 differentials (F/M/R) help?

 

There is no way we can do any analysis close to what your mechanic has done. He could hear the car, we cannot.

But here is advice we can give - you are either going to have to fix the car or trade it in.

Option 1 - fix the car. Your mechanic would have to drop the transmission. You should call Shokan and get a price on a used transmission. Plan on a new clutch while you are in there. Rough guestimate - $2000 - $3000. Much less if you do the work yourself.

Option 2 - trade it in. Instant gratification. You will know all the costs before you make a decision. You will be on the road today (assuming good credit).

If you REALLY like the car and have alternative transportation for a couple of weeks and have $3000 in cash or credit lying around, choose option #1. Otherwise, start shopping for a good 04 or 05 4.2 ...

Good luck,

Bob

 

I hate the idea of trading in when it is in this condition, especially because it would take a hit on the value of the car. Guessing from 6,000 to 3,000. Do you think that is about right?

I have been thinking about it and maybe it could be the axle or the shoe pads?

I appreciate the responses, thanks.

 

I've read your post a half-dozen times trying to see the pattern. You mention that the noise happens whether the vehicle is in gear or not -- if this means you can coast in neutral and hear the noise, then I doubt it is the transmission, clutch, or flywheel. That leaves the parts of the drivetrain that rotate when the car is moving. I have not had problems yet (knock on wood), but things that turn when the car is moving and have joints that can loosen up and clank are the axles or the driveshafts. That means get her up on a lift and inspect and shake the crap out of these to see if there is any play. Could it be in the differentials..maybe..but the axles and driveshafts are more suspect assuming your fluid is good.

Bigdadi suggestion has merit if you have not changed your fluids. I have them changed every 60k (now at 182k). Check the fluid carefully for metal particles (a magnet swirled through the oil is messy but will capture any particles for inspection). Change and check them individually. If one of them is grinding and clanking, I would expect metal fragments. If they turn out clean, see my suggestions above. (I assume the bearings were changed correctly and everything tightened to spec.)

How many miles on the car?

 

My suggestion is merely $200 job, afterall it is a maintenance job, in indy shop specialized Audi/VW/Porsche. I think it is good starting point.

 

Bigdadi,

He has a manual transmission. If it is making noise while coasting, no amount of fluid changes in this world are going to make the noise go away. He would be wasting $200.

ppgoal,

The output shaft of the transmission is directly linked to the wheels and rotates whenever the ar is moving. When in gear, clutch in or out, the input shaft also rotates. So, a bad bearing in the transmission will make noise when coasting (not that CC reported testing results that specific).

So, we are back to take it to a mechanic for a second opinion. Make sure he puts in on a hoist running then start listening for the problem. A screwdriver or hose can be used as a stethescope to identify where the noise is coming from, exactly, and then the damage can be better approximated.

Then, if you like the car, you can decide to fix it or not.

Good luck,

Bob

 

I am sure you are all interested to know the results...maybe not as much as me, but I thought I would advise anyway.
I towed it to a dealership and they performed the service that was due anyway at a price which we agreed upon and I explained that they would have to call me once the mechanic had investigated the problem that had developed. I told them everything I told you above.
I was informed that a bolt from the right front bearing had come loose and has damaged the rt. front bearing, the assembly, and the hub! They cannot explain how a bolt came loose and are somewhat suggesting that the mechanic that replaced the bearings maybe did not tighten the bolt enough.
My thoughts are this: Is that possible? Can a bolt come loose for any other reason? Am I right to be angry with first mechanic?

And I think that the mechanic that replaced the bearings in August is going to have to pick up my car fix that right front bearing, assembly, and hub, and then return the car to the dealer so that I can make sure he did a good job and have a bit of additional work done (like the CV seal). In the mean time, I am stuck without a car or having to rent a car. But the dealership does give loaners if they are working on the car.

The dealer also said that I should call the other mechanic and figure out what I want to do before they do any work to that right front wheel.
Other work that the dealer recommended that I do is fix a broken CV boot seal. But the rest of the car is okay and will probably need maintenance in 9-12 months on control arms, rear brakes, and battery.

 

As far as I can tell-

Viva the dealership!

You saved $$$!

What is the amount of repairs the dealerships totals?

Even if your first mechanic agrees to redo the repairs - is he a trustworthy and skilled one?

 

I wouldn't take it to any mechanic who can't tell the difference between a bad wheel bearing and a bad differential. I would ask the dealer if he knew of a good indy mechanic who could put on used parts, then I would get a used assembly from Shokan to put on. You might even ask the dealer if they would be willing to do this work. If they have to fix the CV boot on the same side (details, dude, details!!!), the extra cost should be minor if negotiated up front. I would then take the old mechanic to small claims court for the cost of the parts and installation. I would also file a complaint with the state against the "mechanic". What a bozo!