alright so i just changed out my tranny, and im having overheating problems. I drained the radiator when i took it out, and i refilled it when i put it back in. Radiator fan comes on, before it NEVER did and i never had this problem. Idles fine, but when start to drive it creeps up and up, and temp gauge gets on hot. What could it be? Water pump? I just did a timing belt also. reps if helped