I have a 1975 2wd F250 with a 302 and a fmx automatic transmission. The transmission has a leak that I haven't been able to stop. It appears to be the pan. I have taken it off and inspected the pan carefully and found no signs of damage, or fractures. I have tried new gaskets, doubling the gaskets, silicone, silicone with gasket but nothing helped. I wiped the transmission with mineral spirits and dried it thoroughly. After filling it with fluid, not starting the engine, waiting over nite a corner of the pan will be wet with fluid with a drop of fluid very slowly dripping from the rear driver side corner which would be expected since it is on the lower side.

I am at the point of considering another transmission. It must be a strong one as I pull heavy trailers and am off road frequently. If I go to a new transmission it would have to have over drive for obvious reasons. Getting another vehicle, or changing to a manual transmission is not an option.

Any transmission experts have any suggestions for locating and stopping the leak, or recommending a good strong automatic with overdrive that will bolt up without having to do major surgery to the drive train?

Thanks in advance.
big big blue

 

When you inspected the pan, was the flange part of what you looked at? If it's not straight all the way across, you can damage the gasket or just not get good contact; if the pan has been over tightened and distorted the bolt holes, it can damage the gasket or not torque properly; If there is old sealant inside of any of the blind bolt holes, it can bottom the bolts out.

A warped flange can be straightened with a hammer pretty easily. If the bolt holes are distorted, you can set the flange on a big socket and tap it flat.

Just a few thoughts that are easy to overlook.

 

Dipstick Oring needs to be replaced.

 

Make sure the pan is flat.

Remove it and place it upside down on a flat area.

Any visible light will show where a high spot is.

It could also be coming from the shift lever seal.