Relocated the vent on a 1992 618 diesel 4x4 trans. Plugged the stock vent hole on the pump behind the torque converter. Drilled and tapped the trans for 1/4"npt about 1.25" towards the passenger side of the top of the trans and approximately 11.875" from the rear flange of the main case...where the overdrive unit bolts to the main case. Installed pipe fittng with adapter and a hose to the engine compartment.

Reinstalled the unit and after it ran a short while I am getting major leak behind the torque converter. Front seal is new along with the bushing in the pump.

Did I drill and tap the new vent fittng in the wrong spot? If so where should I put it? Not much room at all behind the diesel torque converter to run it in the stock location and drill through the bellhousing to run the vent line.

Why did you choose that particular spot to drill for the vent? I don't have a 618 case to measure but it appears you have drilled into the bellhousing area in front of the pump. With the original vent plugged you effectively have no vent at all.

I saw on some 4x4 sites that people were plugging the stock vent in the pump and drilling one just behind the pump. Here is a link to the thread.

http://www.binderplanet.com/forums/index.php?threads/727-tranny-vent.55125/

I offset to the passenger side slightly. Positive I am behind the pump and inside the trans. I have another 618 trans case that is empty and I can measure.

Edit: realized in my original post I wrote 11.875 inches from the rear overdrive flange. The hole is actually 7.85" from the rear flange where the overdrive bolts on.