1999 Carrera Tiptronic oil pan leak and fix
About six months ago I noticed the transmission pan was wet with ATF.
Wrongly assuming the gasket was leaking, I changed the gasket and filler round seal and while I had the sump off changed the filter too.
Torqued everything to spec and filled her up. Everything running smoothly.
Three months later the transmission started to slip. Had a look underneath and the pan was wet again. Cleaned it up so it was totally dry. Took the car for a short run and left it overnight.
Next day the pan was dry around the sides but wet between the drain plug and filler hole.
Wanting to isolate the leak I dried the pan again and taped blotting paper around the drain plug and another around the filler hole. Took the car for a short run and left it overnight.
Next day the drain plug paper was dry and the filler hole paper was wet but touching the inside of the filler hole I could not detect any fluid.
To pinpoint the leak I cut a 50mm hole (size of filler hole) in the blotting paper and taped it around the filler hole. I then stuffed paper into the filler hole and taped that up making sure that the two pieces were not touching. Took the car for a short run and left it overnight.
Next day the paper around the hole was wet and the paper in the hole was dry.
Finally, I knew where the leak was coming from.
Not wanting to spend over AU$1,000 on a new oil pan, I ran some JB Weld over the join between the filler hole and pan. (See photo)
It has been 3 months since the fix and the pan is still dry.
I have also applied 80 Nm of torque to open and close the filler hole plug and this has not cracked the JB Weld seal.
I hope this info will help anyone with a similar leak.