TRNW-2: VW O9G mysterious leak

[Fred Whitaker]

 How high are cores for these?  I would consider just starting over with a complete transmission if they aren't ridiculously expensive.
________________________________
From: trnw2-bounces at trnw.net <trnw2-bounces at trnw.net> on behalf of Steve Everett via trnw2 <trnw2 at trnw.net>
Sent: Tuesday, December 16, 2025 2:31 PM
To: pat schulte <zzyzxpat at gmail.com>
Cc: Technical Discussion Forum <trnw2 at trnw.net>
Subject: Re: TRNW-2: VW O9G mysterious leak

 This one is bolted on to the top of the bellhousing , round, attaching bolt through the middle, two coolant hoses

   Steve

On Tue, Dec 16, 2025 at 3:27 PM pat schulte <zzyzxpat at gmail.com<mailto:zzyzxpat at gmail.com>> wrote:
The usual difference is whether the cooler is remote or bolted on as I recall.

On Tue, Dec 16, 2025 at 12:12 PM Steve Everett via trnw2 <trnw2 at trnw.net<mailto:trnw2 at trnw.net>> wrote:
 We put dye in the fluid and finally verified where its leaking from, the crease where the arrow points,  there apparently is a crack there , can't see it with your naked eye, but the dye was seeping from that crack, same place the other bellhousing was apparently leaking from,  we're going to see if we can get it tig welded by a machine shop locally

    there is a pressure passageway on the other side of that crease,  that is fed by a passageway on the pump body , I've since discovered the valvebody was replaced when it was originally built, there is more than one valvebody for these units,  I don't know if there is a difference in pressures or variations that might explain this ?  I know there are a couple of holes different between VB's relating to lube supply ?

   Steve

On Tue, Dec 16, 2025 at 2:48 PM Donald Day <trnsmaster at verizon.net<mailto:trnsmaster at verizon.net>> wrote:
If bell is porous clean good then coat with epoxy


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On Tuesday, December 16, 2025, 10:24 AM, Steve Everett via trnw2 <trnw2 at trnw.net<mailto: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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--
Pat Schulte
AAMCO Transmissions
Temecula, Ca.
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