727 always leaking

[1KoolBee]

My ‘68 drove me nuts with a leak I couldn’t find. I replaced pan gasket, dip stick o-ring, front seal, shifter seal. Still leaked, mostly when cold. I finally figured out the Bakelite in the neutral safety switch ( old style-single threaded stud) had shrunk over the years and would leak when cold, replaced with NOS (hard to find) and leak was cured for good. Baby powder a good idea, because once there is a leak, the fluid migrates all over and gives you false indications of the source.

 

[mopar jack]

If you have a stock pan check this spot at the front. Some original pans have a weak area that flexes causing a slow leak. I have good results with a flat bar bolted to the pan.

 

[CHGRSE74]

It can be very very difficult to locate in this area as you can see. Back in the day when I was a dealer tech if I had a situation like this I would wash area and dry real well. Add black light dye to the transmission oil (you don’t need much), run till you start to see the leak, or to when you think it will be leaking. Check with the black light, if you can’t determine pull the trans and try locate leak. Drain the converter and carefully remove as to not add any additional oil in the bell housing, than look again with the black light. Black light is very effective at locating hard to find oil leaks.

It does sound like a lot of work and time but may save you much aggravation.

 

[cudamark]

There's also the rare possibility of case porosity. Some castings just have flaws and/or thin spots where fluid will seep right through the case. If it's not a pressurized area, you can sometimes seal it with some 2 part epoxy, such as JB weld. You have to get the case absolutely clean and dry before doing that however.

 

[dvw]

The only case that I've ever seen leak was coroded thru from the outside above the pan rail ledge.
Doug

 

[justavillain]

This weekend I’ll be in the shop looking hard at this. I’ll pick up some powder and more brake clean and hammer down on the jack stands floor a bit and see what’s up.

I have to work in the neutral safety switch issue I have going on so I’ll let it idle for a bit in gear then watch it.