So I have a 1989 Ford Taurus. Mostly dark red but with liberal amounts of that fiberglass and screen stuff I can’t think of the name of. When the car is going, except for the halting way it runs along (worn out automatic transmission) everything’s OK. But the second or less you stop, even at a stop sign, the car fill with a sweetish, fairly nauseating smell. The radiator has not needed refilling with coolant and the oil light is not on. Two questions: what is it and am I going to lose any more brain cells, which are already dangerously low.

Sweet is usually antifreeze, could be your heater core has a leak or the rubber hose to the heater core is leaking. The hose is black rubber and if it has never been replaced it may be leaking. Do you get an oily residue on the inside of the windows?
The leak could also be any point of the hose dripping onto the engine. Even a small leak could cause the smell and you may not see a noticeable drop in coolant levels.

When do you check your coolant levels, on a warm engine or a cool engine?

Agree that the sweet smell is likely antifreeze leaking somewhere. A friend of mine describes it as “stale currie”, having lived in Asia. A pressure test of the cooling system will likey reveal the leak. If it is the heater core, be prepared for a hefty bill; the core is cheap, but there is a lot of labor.

I don’t know why you’d smell a leaking heater core ONLY when the vehicle is stopped. If the core is leaking, it’s leaking all the time, and the air coming through the heater core will smell sweet ALL the time. In fact, if the core is leaking, you should smell it the second you get in the car, whether it’s running or not.

Check the oil level and the transmission fluid levels. If oil or transmission fluid is leaking and landing on something hot, you may smell it when the vehicle comes to a stop, but not when you are driving.

It depends on how bad the leak is. My old mustang had a heater core leak and I couldn’t smell it until the car was on a warm engine and then when I turned on the defrost I could smell it stronger.

check you battery sounds like is burning up. have charging system also. does it smell like routten egg,s

Normally i’d suggest that a sweetish smell denotes a coolant leak, but on a 1989 with a toasted tranny I’m wondering of you have tranny fluid leaking out a main seal and dripping on the exhaust.

I think someone needs to give this a good look-see for leaking fluids, under the hodd, under the dash, and up on a lift.