I have to agree with Michael on this one pick up a new radiator. I would go
pick up a few bottles of 5 min. radiator flush three would probably do it
well (want to clean the inside of the motor to promote proper heat
exchange). Then would run the vehicle gets nice and hot then take it for a
nice 20 min drive so the flush gets all through the system and get's time to
work properly. Then drain the system as much as possible refill with water
and run and drain again then change out the radiator. Then refill with
premixed or 50/50 Prestone with distilled water, test coolant after a good
drive to make sure you have a 50/50 mix.