Need some more description on the smell. Is it a sweet smell, or is it a burning smell? If it is sweet, it means coolant is leaking somewhere. If you smell it in the cabin, chances are the heat core is leaking.
Go to autozone, or harbor freight, and pick up a coolant system pressurizer. Use it to pressurize the coolant system and see if it holds pressure. If it does not hold pressure, and slowly goes down, you have a leak somewhere. Keeping the system pressurized will also help you to track down any leaks, as it may not leak at all unless there is pressure.