Advice tracking down a differential leak.

[mbagge01]

I have been finding a fair amount of fluid buildup on the bottom of the cover for the front axle differential on the passenger side on my rs6. I know that leaks are common at the seal for the flanged shaft but the area around the flanged shaft is completely dry. Has anyone come across leakage from the axle differential cover. On etka, I do not see a gasket there but there is an oring on the inside. It is not coming from the prop shaft as I had replaced the seal a few months ago and it has remained dry in that location.

[hahnmgh63]

I have not had any seepage up there but as you mentioned I know of some flange leaks, although mostly on the rear Diff or at the tailshaft for the transmission (5HP). Maybe use some Brake cleaner and clean it up real well and then drive it for a day and see where it starts from. Was the fluid level very low?

[mbagge01]

I have not tried to check the level yet. As you know, there is no drain plug and just a fill plug for the front diff that looks not easy to get to without taking the wheel off and possibly some other items. I did clean the area up and will check it again.

[hahnmgh63]

Definitely have to take the wheel off to get to the fill plug. I use one of those MityVac vacuum suction tools to get the fluid out. Probably about time to do mine again.

[mbagge01]

Cleaning the area up and looking more closely, I think it is coming from my rear main seal. Any need to deal with it if small leak.

[hahnmgh63]

Probably want to hold off a little while depending on how bad the leak is if it's the rear main seal. Obviously it requires a transmission pull to get at. Just keep an eye on your oil level. I installed an aftermarket Timken seal on mine 10 years ago as Audi only sells the hole Aluminum flange cover with the seal in it. Not a lot of miles on mine in the last few years but so far so good.

[mbagge01]

I talked to my Indy about rear main seal replacement and they say it requires the engine out to do. Is that needed?

[hahnmgh63]

Yes if it's an Auto, if it's a 6spd you can probaby pull just the transmission. Sorry, my post above was a little misleading when I just said a transmission pull. With the Auto you have to take them out as a package before you can split them.