Thread: Oily smell from heat vent on '82 300SD Mercedes-Benz?

When I turn the heater on there is this oily smell coming from the vents. But when I put it on Vent for cold outside air, there is no problem. On this car the heater core should have radiator coolant passing through it and not engine oil. So why should the heater smell like engine oil? The problem isn't getting worse, but it is not getting any better either.

It is not a bad heater core. It it were in fact a bad heater core, the windows would start fogging up inside the car when the heater is on.

Have the car checked for a leaking heater core.