TRNW-2: VW O9G mysterious leak

[Chris and Cathy Kershaw]

We recently had an Acura and a Nissan with small leaks in the bellhousing.
Both had to be driven several miles and left idling for drops to appear on
the ground.

 I would have sworn leaking around bolts when they were back out but ended
up being the converter weld on both. I know you already replaced the
converter just wanted to say oil can do funny things inside a bellhousing.
What about the pump itself?


On Tue, Dec 16, 2025 at 10:25 AM Steve Everett via trnw2 <trnw2 at trnw.net>
wrote:

>   I have an 09 Jetta with a O9G , originally built at another shop, 2
> months after being built it had a small leak from inside the bellhousing,
> small enough that sitting running after 5 minutes there will be one drop at
> the inspection hole at the bottom of the bellhousing,  when you look up
> inside that hole the fluid seems to be seeping from the right side up
> inside the bell,  we pulled the unit, and fluid appeared to be coming from
> around the uppermost bolt on the right side,  (red dot in picture
> attached)  I removed the bellhousing, cleaned everything, resealed the bell
> and used silicone on all the bolts,  reinstalled unit and still had the
> leak,  pulled again,  this time I thought maybe the case was porous in the
> are above and to the left of the bolt, as fluid appeared to be in that
> area,  I cleaned everything with brake clean, coated that area with JB
> weld, resealed the same bolt again, installed a different converter,,,
> installed unit,    same leak again,
>        took a week or so for us to find another unit,  removed bellhousing
> from core unit, cleaned and resealed everything related to the different
> bellhousing,   reinstalled,   still have same leak,
>
>   Different bellhousing, changed attaching bolts the last time around,
> using ultra grey silicone to seal everything,  plenty of silicone on all
> the bolts, changed converters once, ( fluid is not all over inside of
> bellhousing , only on right side, so I don't believe its converter related)
>
>   only explanation would be two different bellhousing being porous in same
> area ?    in the picture attached the fluid originates in the area where
> the red dot is
>
>  Anyone ever seen something like this ?
>
>    Steve
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