Well, as topic states, I do believe that my bevel box has a leak. Just did my dsg and no leak detected. Also the leak, and its a substantial one, is probably all over the subframe. Just where the output propelshaft from the bevel box. But cannot locate it exactly until I take down the subframe. Very tight in there. Also, the smellfrom the oil is typically differential oil smell. Well, will take some pics later today. But, if anyone in here have experienced similar symptoms I am more than happy to hear about it. I am afraid that my bevel box is damaged, and that means likely to replace with a used one. In Norway these sells for about 250-350 gbp. So time will show. 

I also suspect that I maybe overfilled the front diff bevwlbox, and if that is the case, the vent valve will release exessive fluid through that, so it could actually be just that.

Update: yup, the bevel gearbox is probably gone. Leaks out metaloil from the propshaft flange. A lot of oil. So guess the gears are baaad. So need to replace bevelbox.

Updated today. New bevelbox/transmission box aquired from used carsale. Approx 300gbp shipping included. OE partn 0AV 409 053 AF. So starting today to take out and down the old bevelbox.

Will try to take out bevelbox in-situ. Borrowed a long round head hex pipe 1/2 to reach the inner 16mm bolt connected to the main dsg gearbox. It is a pita to reach, but time will show. If it doesnt work, there is no other way around than to take down whole dsg....again.

Hi guys. New update, yes!!! I found the fault based on thorough diagnose and elimination of possible symptoms. I hate to start repacing parts as a deduction method, since it basically is ectremely time consuming and often a pricey path to follow.

Bevelbox output propshaft needle bearing has totally collapsed, I mean, totally shattered the outer parts towards the proshaft connection. No damage to the left right gearbox axle or the drive axle inner axles.

Puuh, so I purchased a used bevelbox 0AV 409 053 AF (original was T).

And friends, a tip. If you have a 4x4 tdi with manual trans, it is no problem to replace bevelbox in-situ. Even the last bracket bolt (lower one on engine) is removeable whem the right drive flange is out. But, if you have a DSG, that last bolt makes it impossible to get the same bolt out due to a larger gearbox. The solution without removing the whole gearbox assembly is as follows:

Remove right bevelbox drive axle flange with a loooong hex 6. Take axle out, and remove the 3 bracket bolts. The last bolt needs to be cut off. Replace with a 8.8 M10x1,5 threadsize shorter one, so it can be used with the bevelbox in-situ.

Now, remove the turbo oil pipe bolt with a 27mm wrench and the upper guiding bracket with a T30 bit. Lay pipe aside and now, the bevelbox bracket will come out. This leaves enough room to remove the most inner bolt that fix the bevebox to the dsg transmission housing. Yes it is tight, but use a long 140mm insex/hex 8 round head on that bolt (it is a 16mm bolt, but no way possible to fit a 16mm pipe there). I used a Sonic insex round head no 8 140mm. Then remove last 3 bolts and voila, the bevelbox is loose without removing the dsg. Oh, forgot to mention that you need to remove dpf and subframe first, but that is almost a routine when doing any job concerning dsg, trans and egr cooler on a tdi.

Attached are the pics of my shattered bevelbox.

Fixed all within 2 hours and replacement bevebox in transit. Paid 340GBP for new and labour is free since I do the job myself. Probably saved more than 4000 GBP compared to if all had to be done at dealer. Maybe even more...

New bevelbox/transmission arrived today. It was bolt on and after test drive, it is smooth!! To sum up, what tip is my best?

 

Well, firstly, when working on transmission on a 4x4 tdi with DSG DQ250 and a webasto aux heater installed,  2 things really makes life easier.

1. Take down the subframe. This gives you a lot of room.
2. Take out DPF. 

With these 2 ****ers out, the rest is piece of cake.

 

What tools saves money?

1. Get a Sonic Insex 8mm ROUND head 140mm long. Partnumber: 83014008. This little ****er is a life saver!!!
2. Buy locating guiding pins for the subframe. Using these will save you from doing a 4-wheel adjustment when subframe is assembled. Special tool partnumber is VW T10096. These are a no-brainer if you plan to do anything on your car infvolving subframe take-down.
3. A looong 6mm hex bit socket, 355mm long. VW T10107A. This is used to undo the right bevelbox drive flange. On a DSG box, this has to come off in order to get the bracket loose. There is NO other way around it with tdi diesel and DSG DQ250 trans. 
4. Buy a Dremel like tool with metal cutter blades. Cut off the above mentioned famous bolt. Replace bolt with a shorter one, M10x1,5 threads. It is impossible to remove that on 2.0tdi with DSG DQ250 if not cut OR if you prefer to take down the whole DSG, be my guest, because that is what VW manual says. Cut it and replace, then remove bevelbox in-situ. Saves at least a couple of hours.
5. Prybar. Use it to take out right bevelbox flange axle (goes all the way through the bevelbox)
6. XZN (spline) 10 bits that has a 100mm long shaft. Makes it easier to take out 6 spline bolts on drive shaft. A lot easier actually.

Good luck!

 

So, my old bevelbox 0AV 409 053T is now garbage and the new slightly used (123 000km from 2014) 0AV 409 053AF is now operational.

 

I estimate just replacement in situ to be approximately on my car is 4h of work on a scissor lift/lying on the floor. With 2 post lift a lot faster.