One time I ran my 91 accord low on coolant and it overheated. I think i caught it pretty fast, but when winter came i had the bad fog problem. Had the heater core done when the blower motor went and it was -30C and i couldn't see bugger all out the windows. The DW had the accord for a few days and on the weekend we were out for a drive to the far side of town and when i looked over from my passenger's seat vantage i saw the temp right to hot. So i dunno how long it had been hot. I suggested carefully she pull over immediately. Against common sense i opened the rad after i bought some coolant. I was hoping it wouldn't bubble up to bad but with the screaming kids and miffed Mrs. time was not on my side. The rad was damn near empty. I realised the rad had split at the bottom tank, so I pulled it and had it repaired. On a rainy day, i had a bit of fog inside. And I can still smell the heater when i turn it on but the smell never went totally away after i had the heater core done in Jan or Feb. It's not cold enough anymore to have the fog problem showing up, but I'm afraid I may have fried a new heater core. now I dunno if i'm just neurotic, or if i've caused the same problem again. Is there a way to tell if your heater core is gone other than the fog problem? Thanks for viewing, I value any comments or suggestions.

 

If the smell never completely dissappeared when the core was first replaced, then maybe the air ducts were never completely cleaned out. That might explain the smell.

With a history of overheating, I'd replace the radiator, not repair it. How do you know whether the tubes are or aren't obstructed by crud? Maybe that's the reason for the overheating & it's not changed?