If a sweet smell akin to maple syrup permeates your vehicle and you know no one is eating pancakes in the backseat, it is time to seek mechanical attention. This sickly sweet smell is far from edible. It may be from toxic liquid ethylene glycol, otherwise known as antifreeze or engine coolant. There are several potential reasons for the odor. They all stem from a leak in the cooling system under the hood.
Leak in Heater Core
The most probable cause for the smell is a leak in the heater core, which is a device mounted behind the dashboard that is responsible for heating the passenger compartment of the vehicle. There are several indications of a leaky heater core. The first is the smell, and you may possibly notice a haze in the air in the passenger compartment accompanied by a greasy film on the inside of the windshield. Also, the floor of the front passenger seat area may be damp or there may even be a puddle on it.
Leak in a Pipe or Hose
A less probable cause is that there may be a leak in the piping or hoses of the engine cooling system. After the vehicle has been parked for a while in a garage or driveway, check for drops beneath it. Coolant comes in two colors: orange, for the extended life variety, and green for the normal variety. The liquid is watery but feels oily to the touch.
Other Leaks
The vehicle's radiator, coolant housing unit or head gasket may also have a leak that might cause a faint odor of coolant inside the vehicle. Droplets from the leaks may run along the outside of the piping before falling to the ground, so it may be a challenge to determine the source of the leak by looking at puddles. Nevertheless, open the hood and check the coolant level. If it is below normal, there is a chance that you do have a leak, and you should add enough to bring it within the normal range. If the cooling system has leaked out much of its fluid, there is cause for concern that your engine will overheat. Check your owner's manual for directions for adding the coolant, as each vehicle manufacturer has specifications. A reputable automotive technician can perform a pressure test on the system to determine the source of the leak accurately.
