While using a torque wrench to properly tighten 700-R4 transmission pan bolts is a good practice, it does not always guarantee a leak-free installation. This popular General Motors transmission is also prone to leaks around the pan because of distorted mounting bolt holes or the pan becoming warped because of improper installation. Setting the pan bolts to 12 foot-pounds of torque is only recommended after the pan is properly inspected and repaired.
Use a 13 mm socket and ratchet to remove the leaking transmission pan. Capture the fluid in a drain pan.
Scrape and wire-brush the gasket mounting surfaces on the transmission housing and transmission pan, then wipe them down with mineral spirits to remove any oil residue. Clean the bottom of the pan as well.
Lay the mounting side of the pan on a flat surface, and make sure it is not warped. If it is severely warped, replace the pan. If one edge, or flange, is lightly warped, use a shop hammer to straighten it. Use a flat, round-headed punch to make sure all the bolt holes are perfectly flat and not distorted or stretched from over-tightening.
Apply a light coat of gasket sealer to the pan. Fit the new gasket in place, and allow the gasket to set. Place a flat, heavy object on top of the gasket to securely fix the gasket to the pan. Install the pan, and torque the bolts to 12 foot-pounds. Do not tighten the bolts in a linear fashion. Alternate side-to-side and end-to-end to ensure the pan is drawn into place evenly.
