White smoke comes from my exhaust pipe but only when my AT fluid is full. If the AT level is at or below midrange on the dipstick there is no white smoke. The car shifts and runs fine. The fluid looks clear (not foamy) and the coolant looks clean too. Though I know the AT fluid goes through the radiator to cool and have heard of leaks developing in those lines and coolant entering the tranny to overfill it, I don't understand how the transmission lines can be related to exhaust. Any ideas?

You probably have a bad vacuum modulator on your transmission. When they go bad, they allow transmission fluid to be sucked into the engine's intake.

Thanks,

 

Is transmission fluid white when it burns?

 

I thought it would be blue.