If you want to do a really aggressive cooling system cleaning, use muriatic acid- - - - -the same stuff that cleans bricks, or goes into a swimming pool to adjust the Ph. Put about 6 or 8 ounces into the radiator after filling it with clear water, run the engine up to operating temp, drain and refill with water. Add two boxes of baking soda to neutralize the acid and run for 5 minutes. Drain, flush with clear water, and refill with a 50/50 antifreeze/water mix. I used that method on a bunch of concrete mixer trucks I used to maintain that were clogged up with limestone dust in the cooling system. Works like a champ!
Jerry
