DIY Gearbox output flange seal replacement 018 409 399 B

[skyegtb]

Finally got round to replacing my leaking output flange seal part number 018 409 399 B, cost in UK £14. The seal had been leaking for at least 6 months and I found a couple of drips of oil under the middle of the car if I left it parked overnight. I didn't top up the oil during the 6 months it was leaking and for info discovered it had only lost about 180ml of oil in that time.

Anyway, the job itself is pretty easy and straight forward. I followed the excellent guide over at audipages which has a full guide for a 4.2 Audi A8. There is very little difference between the A8 and the RS6 apart from the downpipes.

http://www.audipages.com/Tech_Articles/ ... ement.html

Here's how I did it:

1) Lift car off the ground. I have a car lift which makes this job (and all others) much easier, but I guess it could be done with axle stands although I would not particularly wish to do the job that way!

2) Remove exhaust back boxes and center pipes. I have the MTM exhaust which I believe is slightly different in design to the stock exhaust. Note that the downpipes should be secured from below to stop them dropping too far on the flexi-joint.



3) Remove the 3 heat insulation panels from below the main driveshaft



4) Remove the protective plate from below the driveshaft joint at the back of the gearbox

5) With the car in Park and the handbrake on undo the 6 bolts that secure the driveshaft to the output flange. You will need to release the handbrake and put the car in neutral to turn the driveshaft to get the top 2 bolts though.



6) At this point I removed the oil fill and drain plugs and drained off the oil in the box, there was about 700ml in there and the spec says it should be 880ml when full. I had lost around 180ml in about 6 months



7) Use a rubber mallet to tap the driveshaft off the flange, then move the driveshaft to one side (it will rest on a downpipe - I put a bag over the end of the driveshaft to stop dirt getting on to the grease there).



For more space remove one and loosen the other bolt on the central driveshaft bearing to allow the driveshaft to be moved further away from the flange



9) Undo the single T40 torx bolt that holds the flange to the rear of the gearbox and remove the flange, the seal is now fully visible





10) You can now pry out the old seal with a wide flat tipped screwdriver but be very careful not to damage any of the aluminium faces. I personally used a small block of wood to pry the screwdriver against to save any potential damage.

11) After cleaning everything up I now fitted the new seal. I lubed it up and gently tapped it in with a nylon hammer then used a 38mm (IIRC) socket to tap it just inside the hole.

12) Finally I refitted the drain plug, filled 880ml of oil and re-fitted the fill plug then put everything back in the reverse order to how I had stripped it. All in all about 2 hours work and since doing it everything is leak free again

[jamesthecat]

excellent,another money saving how too

[Shoppinit]

Superb write up! Thanks very much. I'll put a link to it in the useful links thread.

[Shoppinit]

Which oil did you use?

Interesting to see how easy access is to the rear lambda sensors.

[el_ringo]

Cool, need that done too!

[skyegtb]

Which oil did you use?

I used the genuine Audi oil G 052 145 S2 - quite costly at £18 a litre but I decided to stick with genuine.

[bilko1]

Is this the seal and flange that Audi have modified due to the leak recurring? Should this be new or replaced on a new / recon gearbox?

[skyegtb]

Is this the seal and flange that Audi have modified due to the leak recurring? Should this be new or replaced on a new / recon gearbox?

Good question! When I did my research before doing the job I became aware of the upgraded parts:

01V-409-809-A £180 (Flange/Shaft)
01V-409-524-B £70 (Cover with seal)

I then priced up a new seal 018-409-399-B which was only £14 and to me it was a no-brainer to just change the seal and see how long it lasted. The seal I replaced on the car was from 2005 when my gearbox was replaced (under warranty) and had done 28,000 miles in the 6 years of motoring since then, so I thought that it had done pretty well.

I would like to think that a new or recon gearbox would have the uprated parts, but could not say for definite.

For info here are some pics of the new uprated parts for future reference:


ETKA part numbers


NEW vs OLD

[mavada]

yes, ive got the same leaking, this is my post...:

http://forum.rs246.com/viewtopic.php?f=2&t=93302
Audi charged me 375 euro...(incl. the updated part, ex labour) thats not gonna happen...

[rossi46]

Just been looking through some old threads and this caught my eye. Hats off to anyone who does this sort of job themselves

One part of this procedure interests me in particular ; I recall seeing on the forum the mention of a very specific process (relating to the monitoring of gearbox temps./oil levels/going up+down through the 'box etc.) to ensure the replenishment of fluids was done accurately. What I'd like to know is when is this applicable and what dictates whether the correct volume of oil can simply be put in vs. needing to do the whole VCDS monitoring ? Is it dependent on what part/parts are being replaced ?

Cheers

[Shoppinit]

You're thinking about an ATF change. This is different. Would be nice to have a DIY for ATF change. I'll do one next I do mine.

[mavada]

yeah i will do mine myself to, but im a little scared to go under the car on 4 jackstands...

[rossi46]

You're thinking about an ATF change. This is different. Would be nice to have a DIY for ATF change. I'll do one next I do mine.

Thanks Shop .. wondered if I might have been confusing 2 different procedures.
Still a bit lost however !

1. So, ATF = Automatic Transmission Fluid, right ? Are ATF and Gear Oil the same thing ?
2. If the more involved vcds process is related to an ATF change, and our gearboxes are automatic, does this not make an ATF change the same as ' changing the oil in the gearbox ' ? I'm trying to understand if the seal/flange that sometimes fail on these engines are components that are considered part of the gearbox or not. If they are ( as I suspect ), then I'm struggling where different types of oil are used.
3. When MRC/Unit 20 /QST etc. carry out a g'box service, are they flushing/replacing ATF or would it be more in line with the procedure listed in the OP's thread?

If I could get my head 'round this kind of stuff, it's make the threads a lot more interesting !

Cheers

[Shoppinit]

Gearbox is full of ATF. This is what is referred to as a gearbox oil change (there's a filter that should be changed, too). Stuck on the back of the gearbox (and part of it for all intents and purposes) is the transfer box (center diff) which has its own gear oil (different to ATF) which is what was leaking in the OP's pictures. So:

1. No
2. Yes
3. The first one.

[R8GXR]

Guys, mines back in the Shop tomorrow to have the ATF flushed again for good measure after running whats in there for a week and its also having this rear seal done, as such should I be thinking they will remove the "gear" oil and fill with new as part of the job or do I need to ask them to do it?