My 2001 Mountaineer's 4R70W transmission overheats. I replaced the filter and drained the fluid from the torque converter drain plug. I filled the transmission with 12 quarts of Mercon V. The capacity is 13.9 quarts. I'm sure there was at least 2 quarts that I couldn't drain. I ran compressed air through all the cooling lines and oil coolers. They are free of blockage. However, I ran the engine with both pressure and return lines fom the transmission and no fluid came out of the transmission. I don't think it has a bad pump since the torque converter refilled and the transmission shifts fine and does not slip.
Is there a bypass valve, check valve, or a sensor that prevents the fluid from flowing? Any suggestion?