What Causes Antifreeze Smell & Water Leaking?

Antifreeze coolant has a sweet scent due to the presence of ethlyene glycol, an active ingredient. While the sweet smell is a unintended property of coolant, it does alert an owner to the possibility of a coolant leak. Coolant runs throughout an automotive engine, the radiator, and into the heater core, which is located behind the dash panel inside the passenger cabin. If you smell antifreeze and you see water or coolant, that means you have a leak that needs to be fixed.

Leaking in Cabin

If you come out to your car and find a pool of water in the driver or passenger footwell along with the occasional smell of coolant, this is a likely indicator that the vehicle heater core is leaking. The heater core is the device that provides heat, and it is essentially a miniature radiator that has rubber hoses connecting it to the engine cooling system. Heater cores can degrade over time, particularly if the engine coolant has not been periodically replaced, and can leak from the rubber hoses or from the end tanks of the core itself. Since the heater core is in a compact area, the leaking coolant pools and spills down through the dash onto the floor of your interior. Unfortunately, heater core replacement is a very expensive repair, due to the amount of labor required to access the core. While heater core themselves are cheap, they are buried in the center dash of a vehicle, thus require disassembly of the dash.

Leaking from Radiator or Overflow Tank

The radiator is the main heat exchanger for the engine. Located at the front and center of the engine, it will have fans attached to the backside, and thick rubber hoses running from the endtanks to the engine block. Over time, radiators can degrade, particularly when exposed to salted roads. In addition, many factory radiators now come with plastic endtanks on the radiator, which are prone to cracking. You can attempt to locate a leak from the radiator or overflow tank by looking for crusty green or red deposits (the deposit color will match the color of your coolant) on the radiator, hoses or overlflow tank. Before you start your car in the morning, check underneath to see if there are any drips or small pools of coolant.

Coolant in Oil

If you find no leaks or pools of coolant, yet you are losing coolant and can smell it while driving, you may have a damaged engine head gasket or cracked engine head. When the head gasket on an engine fails, this allows coolant to mix with oil, resulting in white smoke from the tailpipe, coolant in the engine oil, and the sweet smell of antifreeze when driving. This problem signifies significant engine trouble, as the head gasket will need to be replaced. One way to check for this is to wait till the engine is cold, then remove the radiator cap and use a flashlight to examine the coolant. If you have a bad head gasket, you may see oil in the coolant. You can also carefully examine the block where the head meets the engine block. With the car idling, you may be able to see puffs of gas leaking from holes in the head gasket if you spray this area down with soapy water.

Monitor Coolant and Seek Repair

Regardless of the source of your coolant leak, it is a serious problem that cannot be ignored. Since you are losing coolant, it is important that you check coolant levels and keep the system topped off until you can get your vehicle into a repair shop. Be sure to check your owner's manual and purchase the correct type of coolant, as they are not all the same, and you can cause catastrophic damage by mixing different types of coolant.