Signs of Low Antifreeze in a Car Engine

by Meaghan Ringwelski

Antifreeze is an important component of an automobile. When a car runs low on antifreeze, problems occur. Sometimes the signs of low antifreeze may go unnoticed for awhile. When antifreeze levels get low enough, though, a car begins exhibiting enough signs that prompt its owner to have it checked by a mechanic. Knowing the signs of low antifreeze can help drivers avoid costlier repairs in the future.


Antifreeze works within a car's cooling system. It prevents liquids within that system from freezing to a solid state. The most commonly used form of antifreeze is ethylene glycol. It is preferred because it is inexpensive, can be mixed with water in any ratio, doesn't react chemically with any other substance within a car's cooling system and has a suitably high boiling point.


One of the most common signs of low antifreeze in a car is a sweet odor that is persistently present within a vehicle. When a driver notices such a scent, he should check the floorboard beneath the carpet on the passenger side of the vehicle. Any liquid or dampness discovered there is likely to be antifreeze that is leaking from the car's heater core.

Greasy Film

Another common sign of low antifreeze in a car engine is a greasy kind of film on the interior of the windows. This film is often mistaken as normal dirt that has accumulated within a car, but it recurs right away after being cleaned. Drivers should be aware that it usually signals low antifreeze in a car that has resulted from a leak in the heater core.

No Heat

Low antifreeze in a car engine typically causes its heat to quit functioning. This symptom is normally only noticed during the winter months, when a driver relies on the heat to be comfortable in her vehicle. This symptom is also frequently due to a faulty thermostat. However, low antifreeze needs to be ruled out, and the heater core should be examined for leaks.


The signs of low antifreeze usually result from a leak in the car's heater core. Such leaks typically occur when a car's antifreeze and cooling system are not flushed on a routine basis. This causes rust to build up within the car's cooling system, leading to leaks in its heater core.

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