Hello,

I'm noticing a bit of a rummbling sound coming from the rear end when making sharp turns under power. Like when pulling out of a parking lot into traffic, or when making a sharp U turn. I just flushed the rear end, and the noise persisits. There is an ever so slight leak coming from the axle shaft seals. Literally, just a drop of dampness in the joint itself... Could the bearings/seal be causing this?

Thanks,

Aaron

 

Check the tierod end boots on the upper links on the rear end of your 1997 A6 Quattro Avant. If the tie rod ends are bad, they may squeak when you push up and down on the rear bumper. Check the rubber exhaust system hangers.
Sometimes it is difficult to determine the actual source of a rumble, when inside a car. Are you certain it is not coming from the radiator fans? You may have to put the car up on jack stands and manually rotate each wheel. Check all CV joint boots, including those on the propeller shaft. Also, the propeller shaft has a center bearing which may fail at high mileage.
Have you ever checked the fluid level in the front and center differentials. The center differential fill plug is above the propeller shaft front CV joint heat shield, which is above the catalytic converters.

 

Its prolly actually the front diff... mine does this.

 

The 1996 and 1997 A6 Quattro with C4 chassis front differential may not have a drain plug. The fill plug hole determines the level of gear oil. The bearing at the left front flange is packed with grease, per Bentley, so if there were a gear oil or ATF leak on the left side, then the bearing and seals would need servicing. An ATF leak may come from the torque converter seal. There is an access plug some where near the left flange, which is used to check for these leaks.
The engine and transmission mounts should also be checked for cracks in the rubber.

 

Would such an issue with the front diff be causing sounds in the rear? A bit confused by this one... I've had other AWD vehicles, and have yet yo have an issue with the front lead to symptoms with the rear diff. I'm begining to wonder if it's something as simple as bearings.

The trans and front diff are just fine, having recently had a flush 8000 miles ago. No leaks of any sort up front.

Thanks,

Aaron