That hose plugging won't increase the pressure in the cooling system unless the radiator and heater core are BOTH also plugged.
Exactly, Libby. I'm pretty sure that's what happened. It was ugly. I replaced the entire cooling system after seeing the gunk in the heater core and air bleed hose.....just to be sure. Neglecting cleaning the system every few years or as needed caused the problem. Thanks for the comment.
Thomas
Vancouver, WA