Seal/block water pump opening. White Vinegar, or evaporust, or Thermocure (basically concentrated Evaporust you mix with distilled water), or Rust911 are all good options. Mine was somewhat worse. I started with white vinegar, a couple of times, then went to thermocure a couple of times. Thermocure and evaporust turns very black, and when very black has lost its effectiveness. Repeat treatments till you are happy. Flush/backflush extensively with garden hose. Then last time with distilled water. If using vinegar, some leave in for up to a week to a month. If using vinegar last flush with distilled water/baking soda mix and let it sit to neutralize the vinegar . Then some blow dry with a leaf blower to insure everything is flushed/blown out.
Put in an upper hose filter.
Distilled water summer coolant.
If going to use distilled water coolant, add 14 ozs. of Napa Macs 1300 Rust Inhibitor and a bottle of Red Line Water Wetter, These will help prevent Rust/Scale, and additionally have some Water pump conditioner/lube. Additionally Water wetter may increase the efficiency of your system and lower the coolant temp by 5-10 degrees.
For winter, drain, add 50 50 green antifreeze with 14 ozs Macs Rust Inhibitor, this can drained, saved, and reused multiple times, just add the inhibitor each year. Flush your radiator cooling system thoroughly, and refill with the summer coolant mix.
Anti-freeze summer coolant.
Purchase 50 50 premixed green, or mix purchased green concentrate with distilled water (cheaper to mix yourself). Add 14 ozs Macs Rust Inhibitor, add again in fall if not replacing anti-freeze. Personally to be on the safe side think you should Drain, flush/ back flush every 2 years and add fresh antifreeze/inhibitor. You may want to use a commercial flush for flushing.
Again, opinions may vary
