What will happen if you try to push start a auto transmission car?

Answer 1

An automatic transmission uses a fluid coupling (the torque converter) between the engine and transmission. It is not designed to work in reverse. A manual transmission, on the other hand, has a direct connection between engine and transmission once the clutch is let out. It is true that hydraulic pressure is required in order to cause an automatic transmission to transmit powerflow (or couple) internally. The pressure engages reaction devices such as multi-disc clutch packs or bands to place planetary gearsets in to action. Most modern vehicles have pumps that are driven by the torque converter quill (the part that plugs into the face of the pump housing) and the torque conveter is driven by the engien flywheel. In these vehicles the engine must be running to create hydraulic pressure. Pushing the car will simply turn the driveshaft which is connected to the output shaft of the transmission. Since the output shaft does not transmit any power flow forward toward the engine without hydraulic devices in play, the effort stops there. In some older vehicles that had hydraulic pumps in the rear of the transmission it was possible to push start them. When the driveshaft turned the output shaft of the transmission, sufficient fluid pressure could be developed to cause the reaction devices to engage and pump enough fluid into the torque converter to allow the converter to turn the engine. The vehicle would normally have to be pushed 35 mph or so in order for this to occur.

Answer 2

It won't work like a standard will, a standard you manually engage the gears, while keeping the engine disengaged with the clutch. With an automatic, that's not the case, it won't allow you to throw it in gear. Why would you want to pop start it? Does it not start? Just pay a towtruck to tow it. If you call a garage that also has a towing service in-house, ask if they could give you a discount rate for towing if they fix it too. Most places do.