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Discussion Starter #1
I have a 2003 1.8T Passat Wagon w/ 01V auto and FWD. I have a minor leak in the front right axle seal. I looked in the Bentley and was surprised to learn that's the differential and it takes 75W90 synthetic gear oil, not ATF fluid. The oil smells burnt (I'd guess there's little left so it's overheating and burning up) and I would like to drain it out and refill from scratch. Unlike the 4WD vehicles the FWD differential does not have a drain plug, just a fill plug.

Has anyone drained their gear oil from the fill port, is it possible to have a fluid pump suck it out? I'd guess it's kind of a thick oil for a pump. Also the Bentley says for filling it takes 5+ minutes because the oil needs time to settle into the differential, so maybe it will not be possible to suck out all the burnt oil, or I would have to do it in stages.

Eventually I will replace the axle seal, typically I work on the car in the summer and I need to do something temporary to get through the winter. I am also thinking of adding a little AT-205 sealer to slow the leak. Right now it's an occasional drip but I'm really not happy with the smell that's not a good sign.

Also: If anyone is buying the bentley book I suggest buy the 2 book set instead of the 1 huge book (that is the same as the 2 book set but in one book). I have the 2 volume and holding one of the books in my hands to read for a long period of time is annoying. It would probably be much more difficult to move around if it was all in the 1vol mega book I'd have to leave it on the table.

In hindsight this thread may be more appropriate for garage sub-forum, please feel free to move it.
 

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If my memory serves me correctly, there is a drain plug on the lower passengers side of the transaxle just forward of the axle flange.
 

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It's actually a fill / drain plug. You'll need some kind of extraction device to suck out the oil.
The oil is designated as 'lifetime' from the factory. An actual drain plug is not present.
Should the chance I ever have my wife's car apart again, I'll install my own drain plug. A 12mm hole in the bottom of the transmission casting will have ZERO effect on integrity.


97736
 

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Discussion Starter #5
Thanks. The plug w/seal is 01V409057 M18X1,5 (not to be confused with 01V409057A which is smaller). I ordered the plug for the seal since the seal isn't sold separately. I will look for a pump with some tubing that has an OD less than that (ie less than 3/4").
 

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Yes, my writeup is in the Info Forum, but the pics are dead. Even the 4mo Tips do not have a drain for the front diff. Only the manual trans have drains as they share the gear oil for the trans, front and center diffs. I did the change on my 1st Passat, but never on my wagon (162K when swapped) or my son's wagon (248K and climbing). Now I just check the level and top off if needed (only if it leaked).
 

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I think it was my 1st ever writeup, done with the help of Pete1 when he still lived nearby.
 

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I have a 2003 1.8T Passat Wagon w/ 01V auto and FWD. I have a minor leak in the front right axle seal. I looked in the Bentley and was surprised to learn that's the differential and it takes 75W90 synthetic gear oil, not ATF fluid. The oil smells burnt (I'd guess there's little left so it's overheating and burning up) and I would like to drain it out and refill from scratch. Unlike the 4WD vehicles the FWD differential does not have a drain plug, just a fill plug.

Has anyone drained their gear oil from the fill port, is it possible to have a fluid pump suck it out? I'd guess it's kind of a thick oil for a pump. Also the Bentley says for filling it takes 5+ minutes because the oil needs time to settle into the differential, so maybe it will not be possible to suck out all the burnt oil, or I would have to do it in stages.

Eventually I will replace the axle seal, typically I work on the car in the summer and I need to do something temporary to get through the winter. I am also thinking of adding a little AT-205 sealer to slow the leak. Right now it's an occasional drip but I'm really not happy with the smell that's not a good sign.

Also: If anyone is buying the bentley book I suggest buy the 2 book set instead of the 1 huge book (that is the same as the 2 book set but in one book). I have the 2 volume and holding one of the books in my hands to read for a long period of time is annoying. It would probably be much more difficult to move around if it was all in the 1vol mega book I'd have to leave it on the table.

In hindsight this thread may be more appropriate for garage sub-forum, please feel free to move it.
Most probably the axle seal is not gone, but there is play in diff bearings, and that's why is leaking. Remove heat protection shield and shake the shafts to establish amount of play. If there is, you should adjust the diff bearings, because changing the seal would not help. Also, oil draining would be done at same time, since when diff cover plate is removed for access, the oil would be completely drained. A bit involved for sure, but doable. Good luck.
 

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It could be either, I replaced the seal on my 4Mo a long time ago and it worked. There is a thread on AudiZine about someone who had too much play in the bearing (C5 A6, same trans). Not sure about the resolution.
 

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Discussion Starter #11
I worked on it this week. To remove the plug I needed an impact wrench with an 8mm hex, some wobbles and a u joint (all impact grade). It was too difficult to get any leverage on it with a ratchet because there's almost no room in any direction to swing and it's at too much of an angle with the wobbles.

The washer on the plug is a special curved rubber washer and as I mentioned earlier I had ordered a replacement plug w/washer, but the original washer was in excellent condition so I reused it. I think this is the first time I've ever found an o-ring on the car that was in excellent condition. If anyone reading this is in a similar situation and actually does need a replacement audiusaparts sells it for $9 and has free shipping.

I was unable to extract any fluid from the differential. I thought maybe that was because it all leaked out, however I was only able to add 150ml (yes, I did follow the 5-min wait procedure in the Bentley). I think the transfer pump hoses I used were too large and rigid to really get down in the differential fluid. Anyway maybe this is better because the 75w90 fluid I'm adding has AT-205 (leak stopper) that I mixed in (make sure to shake thoroughly), and this way I can just keep adding a little of that mixture over time until the leak stops, and I won't over do it.

I did manage to reinstall the plug (22 ft-lbs) using wobbles and a torque wrench.

Most probably the axle seal is not gone, but there is play in diff bearings, and that's why is leaking. Remove heat protection shield and shake the shafts to establish amount of play. If there is, you should adjust the diff bearings, because changing the seal would not help. Also, oil draining would be done at same time, since when diff cover plate is removed for access, the oil would be completely drained. A bit involved for sure, but doable. Good luck.
What do you mean shake the shaft? Is it supposed to move at all? I put the car in neutral and took the tire off and I could rotate the shaft with some difficulty, and I could move the shaft in and out a little but I couldn't shake it.
 

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Play as in side to side or up and down. My old trans had some when I pulled it at 162K and it had just started leaking again. Since you did not have any play when shaking it, you should be fine with just a seal if the leak continues.
 
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