careful on flushing the radiator if it has the evil servo ,the plastic and gaskets wont like any foriegn chemicals,best to take the radiator out to a shop to be cleaned ,and just flush with water after reinstall.Its happened to me on a 79 300td. The servos are priced like gold and have few remedies beside total replacement.Heard your only to use a certain radiator fluid to ,a type of zerex brand .