Hi. I have a 2000 A6 2.7T with 140K. I was advised to have my read differential seal replaced at a cost of $325. As you all want your audi to last as long as possible and put the least amount of cost into our audi's I ahve been driving with this nagging issue for two months and wondered from you all IF I should have this done? Also, does anyone know why this seal costs so much (Labor) I assume but would you get this done? I am not noticing anything different in terms of driving, turning, or braking.
I look forward to hearing from you.

Thanks,
DAN

 

Please advise

 

We see no technical issue described here, but financial!
What is the reason for replacing the seal?
Losing fluid?
Drive train repairs are delicate matter as bad work will not be evident right way.
I’d suggest you seek second opinion – always.

 

You are correct about the cost: labor. It looks like a PITA to replace. I was told mine leaks as well. I don't have any spots on the driveway due to it, so I will just check the fill level every once in a while until I notice it getting worse, then I will tackle it. If you have your oil changed, the service should check this for you. If you DIY your oil changes, just jack up the rear, pull the plug and stick your pinky in every oil change.

Bob

 

The rear differential has a seal for each half axle and another one for the propeler shaft. What you need to do is to check the differential fluid level and add fluid if it is low. If you have a bad fluid leak, then you may have to replace the seals.
You should also check the fluid level on the center and front differentials. The center differential is more difficult to check, since it is above the catalytic converters on many cars. Hence, it is more important to replace a leaking center differential seal.
The reason it cost so much is that there is a lot of labor involved and some special tool may be required.
I replaced the rear propeler shaft seal on the rear differential of a 1998 Audi A6 Quattro wagon with the C4 chassis. Both parking brake cables had to be disconnected and the front of the differential dropped down to remove the flange assembly with a slide hammer. The flange assembly has to be taken apart to replace the seal. The assembly is held together by grip rings and by a press fit at the ball bearing. I had to wait a week to get the parts from the dealer, as most of them were not listed online. Also, during disassembly and assembly care must be taken to not damage the ball bearing. I replaced the ball bearing as the car had over 100,000 miles. I installed the new bearing without pressing the ***** against the races. I used a large socket to install the bearing in the housing end cover. I used a large steel tube which fit over the shaft and contacted only the inner race to press the flange shaft into the bearing.
The seals are an item which may require replacement several times over the life of a vehicle. As there are many seals on an Audi, it may become rather expensive.