How do I stop my transmission leaks?

Question:

I have two street rods, both of which have 350 cid small block Chevy engines and Turbo 350 automatic transmissions. If they sit for a while they drop transmission fluid on the shop floor.

Is there a cure for this problem? Arnold Johansen

Answer:

When your engine is running, automatic transmission fluid is pumped into the torque converter and throughout the transmission. When the engine is not running, the transmission’s mechanical pumps are no longer pumping and fluid in the upper areas drains back down, ultimately reaching the pan.

There are check valves that should prevent fluid in the torque converter from completely draining out but like everything else these can fail. Replacement requires removal and partial disassembly of the transmission.

As the fluid runs down and the level in the pan rises it reaches seals and other potential leak points where it can escape. These typically include the points where components such as the fill tube, dipstick tube, modulator, shift lever shaft, and sensors install into the case.

In some instances, changing the Oring seals on these components will cure or at least diminish the leaks. Replacing the old fluid with new fluid can also sometimes help because the viability of seal conditioners, which help keep seals plump and effective, will normally decrease over time.