2003 jetta tdi 5 speed transmission oil leak

Have no luck with those known to be very reliable 5 speed transmissions. Last year changed original tranny due to problems with 5th gear at 400k. Installed different 5speed tranny from tdi with 200k and now have big leak at the bottom of housing where transmission is bolted to motor . Car drivers normally no issues with tranny or clutch does not slip ,pulls strong ,suprisingly given such a big leak . Car leaves palm size stain after 1hr parking .Checked output CV shafts there are dry guessing must be main center shaft seal leakin.only place where I see drops of brown clear tranny oil is at the bottom of clutch housing . Will changing this main seal will solve my problem ? Cant find much info about changing this particular seal . Any help appriciated.

Sounds like rear main seal as you have suggested. Need to pull down the tranny and replace. Once there, you might as well have a look at clutch and other components considering its a big job.

This acts as the input seal

https://www.idparts.com/transmission-input-shaft-sleeve-seal-a3b4a4-p-2467.html

and what the throw bearing slides on.. It should be changed whenever the trans is out really. I have not really seen any major leaks from THIS seal before, but maybe it was damaged on install. Just three bolts to change this seal.

If you pull the trans look for damage to the left side (closer to drivers side). This spot (the circle beside the input shaft) sometimes get scuffed/hit by turning stuff, like in this picture, enough scuffing it will leak.

https://usrallyteam.com/images/pinbrace_center_02a.jpg
https://usrallyteam.com/images/pinbrace02a_b_07.jpg

If the oil is clear it’s not the rear main seal of the engine but the input seal of the transmission. Don’t drive it or else you will wipe out the transmission.

imo000 said:

Don’t drive it or else you will wipe out the transmission.

Click to expand...

you definitely take a chance of burning of 5th gear if this is the case, most common when fluid gets low.

If you need another trans all together I will have one for sale. worked fine when removed

Thank you guys for all input. Yes its definitely gear oil not engine oil . And got this main center shaft seal .German made. Clutch was changed..last year .leaver bearing had no play at all . Is anything else I should check/replace when got tranny out of a car?

Clutch wasnt worn ,easily could have leave it for another 100k.Steve6 thank you for offer of whole working transmission . If something goes bad will most likely buy it from you. Thank you also for this link with picture of seal bushing . I just ordered one before just had oring seal with spring inside only and thought it's all I need . So there is two one single and one with this bolt on bushing correct?

QuickTD said:

The pressure plate fingers often wear a hole in the pinion bearing boss inside the bell housing when the clutch is severely worn. I have seen it several times. How bad was the clutch you replaced?

Click to expand...

I've seen this too.

Not to scare you, but the clutch fork can fail too. Sometimes it cracks in the middle, sometimes a hole wears through the ball socket. Best bet is to replace it if it wasn't done at the last change.

Thank you guys again for all this advice. All looked good when I replaced my original tranny 20k ago . And yes I make sure is full of oil or even I bit above over fill hole (lifting car) .
Till this moment car is driving fine without any problems with engaging any gear and pulls strong ...no noises .Except for the fack bottom and only bottom of bell housing is covered with dripping gear oil. I know will have to take tranny off the rge car to see where is leakin . Already both seal and bushing with seal . Will check for play on input shaft ...maybe bearin is bad ...but again car is driving and sounds normal

It won't be driving like normal if it runs out of oil. The transmission doesn't have much in it to start to be careful. Overfilling the transmission is not good, it can cause the seals to get pushed out if there pressure goes too high.

I kept adding oil every second day to make sure there is enough* oil before I fix it. Steve6 was right on the money .

Problem was with this bushing ,input seal . All three bolts holding it where undone to half of tread . And was damaged. No wonder was leaking so bad . Cleaned with brake cleaner all surface inside the housing* and Replaced this seal/bushing and install 3 bolts holding seal on blue locktite .

Problem fixed . Thank you guys for all help and suggestions .

https://www.idparts.com/transmission-input-shaft-sleeve-seal-a3b4a4-p-2467.html