I have a 700R4 that was in a freshwater flood about 6 years ago. The water level got almost to the exhaust ports, but not into the ECM. I figured it was all trashed and a waste of effort, so I let the car sit after removing the interior and carpet and drying it out before mildew could get started.
I happened upon some motivation recently and decided to drain things and actually take a good look. First I drained the engine oil, no sign of any water at all. :-) Dumped a quart of motor flush thru, lit it sit in the pan for an hour and drained. Again, no sign of "milk shake" or sludge. Poured five quarts of "cheap" oil in and let it sit overnight. Drained, installed new filter, and filled with new oil.
That made me feel so good, that I took the transmission pan off (700R4). Again, the fluid looked great as it ran out everywhere (why don't they install drain plugs at the factory), no sign of rust anywhere that I could see. However, the pan did have a little less than 1/4" of milky white goop in the very bottom. I assume that a small amount of water came in thru the vent on top during the flood and settled into the pan. Not knowing the interior of a 700R4, can I also assume that said water would have _ALL_ ran down to the pan? Are there other places that water could be trapped such as in the tail section? The engine has not been cranked at all since the flood and I'm fairly certain that the water never got high enough to get in thru the exhaust ports. I have a new pan gasket, filter and 5 quarts of fluid. Do you guys think it would be safe cranking the motor up after a fluid/filter change? I don't want to destroy the tranny, but I don't want to have it rebuilt unnecessarily either.
BTW, I will have drained the differential and gas-tank/fuel-system completely before attempting to crank it up.