Clean radiator, cool engine, coolant PH, flow, fans, shrouds.

So, after the mild citric acid soak - fail, I filled rad with swimming pool muratic acid (dont know concentration) but it was straight from bottle (almost a gallon worth). Sat for 48 hours with intermittent sloshing and I dumped it out and back in once too for additional circulation.

I am really happy with the results. 40 dollar radiator and 6 bucks of acid. Yes!

Before and after: