Tried the coolant flush with a garden hose trick, got a shower instead

Forgive me but this is the kind of stuff that keeps me coming back to these forums, it's the exact comedy of errors that happens when you rush and trust a tip from some guy at 7am who probably learned it from another guy. Did the radiator cap really "shoot off like a rocket" though, or did it just pop off and spray some coolant? Because caps have a spring and a vent, they don't usually launch into orbit, unless it was already half off. And were you actually flushing with water while the system was hot? That's the part that would make it go everywhere, not the trick itself. The garden hose method is messy, sure, but the cap being loose is the whole problem, and that's on you, not the tip. So it sounds less like a lesson about forum tips and more like a lesson about doing a 30 second check before you grab the hose.