well I don't know how he can assume it was the tranny as far as I know they don't make noise when they get hot. Let me tell you what happened to me on vacation a few years back , I was driving home from the beach in my then 2000 short wheel base montana(160k) up through the west by God virgina mountains fully loaded with wife and 4 kids plus a clam shell bulging and the ac on,but the tranny was hunting between 3 and od(shifting back and forth)and before you know it my temp gauge was very high but not hot anyhow all of a sudden it down shifted in to 3 and would not shift out of third until we were on the flat for a few miles probably until the temp lowered itself. After that trip the tranny began to whine ever so slightly then as time and mileage went by the whine got real loud untill the kids and wife were embarressd to ride in it ,you would hear it before you could see it . So does your tranny whine ? If your van is hunting alot then shift it into 3 to prevent this . And last of all I guess a tranny cooler wouldn't hurt either(something I want to do). Good luck and enjoy your vacation and keep us posted.
