We have a 2001 e7 427 rd688s, it has very low mileage on overhaul. Everything but crank replaced. It pushes coolant when at rpm. Doesn't push at idle. Does not over heat. We replaced air compressor,stat, radiator, fan and clutch, water pump, checked all hoses. Truck runs great. Found no hydrocarbons in antifreeze. It seems like a flow issue as it doesn't pull all the antifreeze back when cooled and pushes below the temp that would open the stat. Any thoughts would would be greatly appreciated. If I can't figure it out in going to put it on the dyno. Trying to avoid that. Thanks for any help.
