Recently, when I turn my heat on after the car has been on for a while, something under the hood starts steaming. If the heat is on when I start the car, it doesn't do this. It doesn't smell like just water that is evaporating. It almost smells like coolant. By the time I get out of the car to see what was steaming, it stops. Could this be related to my heater core/valve?

I have an '82 240D (W123).

TIA

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1982 240D - 350k miles and still going strong...
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