A few months ago, I blew the head gaskets in my Montero. Had it towed to the nearest shop (I was at a friends house 30 miles from home), and they said something was blocking a hose, preventing coolant from getting to the engine and that's why it blew. I investigated myself. Nothing was blocking, but there was a 2-inch hole in the upper radiator hose.
I told my old Auto teacher about it, and he said to try a sealant called Steel Seal. I'm iffy on sealants, but I trust this guy 100% and he swore by it. So I ordered it, replaced the hose, and it worked. Engine temp never rose again. She runs fine now.
But..
Due to the sealant running through the cooling system, it's plugged up my heater core. Not the end of the world- I can still get hot air from the engine.

But I have two questions:
1) Has anyone ever fixed their heater core? I understand it's a PIA..

and 2) I just bought a replacement engine (to fix all my engine problems at once), and with a clean cooling system (no more sealant), will my heater core return somewhat to normal?


Thank you for any help; I'm new here