Guess I might as well settle in here as a regular the way this cars going. Got a 2011 Vic w 280k that seems to have developed a heater box coolant leak over the course of a couple hours yesterday. Defrost stopped working (in the rain) and eventually steam started pouring out the dash vents. The engine began to overheat same time the steam started so I pulled it over to cool off for an hour and nurse myself back to health with a beer. Got back in for the leg home and noticed about 1/4 cup of coolant on the pass floor board mat. So it was no surprise when she started overheating again after about 3-4 miles. The reservoir drank about 2 gals of distilled water and that got her the rest of the way in.

Testing back at the house reveals a pouring leak coming out the bottom of the car right on top of the cat converters way back at the firewall. Crawling underneath, the leak was seen to be coming from a short 1" tube that sticks out from the firewall right above the cat. Not for sure but I would almost bet this is a drainage tube for when the heater core springs a leak.

How likely is this to be my heater box (don't see how it couldn't be) and what do I start doing to get it swapped out? Just got the big heavy shop manual so that'll be a help. I've seen some youtube heater core swap out videos but the closest they come to my year is maybe a 2003.

Good advice. ^^

Being it’s high mileage and if the cooling system overall condition was sort of an unknown, I’d bypass the core and again pressure test the system. Running it under normal conditions as a check, or, better would be to use a system pressure tester on it to test it’s integrity under max specs. Rad, head gaskets, pump, primary/secondary hoses etc. Any possibilities of leak/weep points..

If you need shop info on the job, let me know..