I am working on a 72 C10 with a 307/350 turbo combination. It seems to leak a bunch of transmission fluid after setting for a period of time. It had no sign of front or rear seal leakage, so I replaced the filter and pan gasket and then test drove it for several days. No leaks! After setting for a month or so, it had another big puddle of ATF under the truck. Hard to tell where it is coming from (closer to the front of the transmission than the rear, judging by the puddle). When I checked the transmission fluid level after this last big leak, it showed way OVER full! I know the fluid level was right on when I replaced the filter. Once I started the engine and shifted the transmission, the fluid level was barely on the dipstick. What gives? What is causing this crazy intermitant leak?
i had the same problem with mine it ended up being the front pump try that and see what happens:+ }> :+
The converter is draining down while sitting. This allows the fluid level to go above the selector shaft seal and the speedometer input seal. Replace these before the front pump seal and your problem will probably be reduced or eliminated. It is easier than doing the front pump seal! Good luck.
Had the same problem with my 350. Turned out to be the speedometer seal. Four dollars later, the leak stopped. Mike
