2010 DODGE 6.7 COOLANT NOT GOING BACK IN RAD FROM RES.
Replace the radiator cap, had the same problem on a Bronco, repalced the cap no more problem.
did rad cap 2 times and water pump as well
Have you checked to make sure the system is pressurized, if it won't hold pressure it won't allow the coolant to feed back as it cools and the pressure slowly bleeds off.
yes the pressure stay up put a rad test on it and it holds pressure.
Then the only thing I can think of is hoses collapsing during cool down or a really stubborn air pocket.
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