Does Car Coolant Evaporate? Can it Evaporate too Much?

Coolant loss is expected under normal circumstances but if your car coolant evaporates too quickly then it is something to worry about. Since the loss of car coolant may indicate a more serious issue.

If this problem of low car coolant is left unchecked, it may lead to a blown gasket or even worse a seized engine. In this article, we will cover that does car coolant evaporate, and if yes then why does this happen.

What is Car Coolant?

Car coolant, otherwise known as anti-freeze is primarily responsible for maintaining the temperature of the engine block. By keeping the temperature under check, it ensures that associated parts like the head gasket and water pump stay intact. It also reduces the friction between mating parts of the engine such as pistons and cylinders.

The temperature of the engine block can rise up to 700 degrees Celsius during normal operation. The highest temperature in the engine block is recorded in two places. One is near the exhaust valve of the cylinder and the other point is where spark or ignition takes place.

There is a dire need to keep this temperature on the lower side, in order to prevent any permanent damage to engine parts. That’s where car coolant comes in. It absorbs the excess heat from the engine block and disposes it into a sump. This cycle continues until the desired temperature is achieved.

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Does Car Coolant Evaporate?

Car coolant is just like any other fluid. It has a fixed boiling point and when that temperature is reached it starts evaporating. Two different configurations of car coolants are usually available. One consists of ethylene glycol and the other one consists of propylene glycol. Typical boiling points of EG and PG are 255 & 257 degrees Fahrenheit respectively.

Car coolant is basically a mixture of water and an anti-freeze agent such as ethylene glycol or propylene glycol. The water has a lower boiling point of 100 degrees so it might evaporate before and leave the anti-freeze agent on its own. This can compromise the ability of coolant to cool the engine.

That’s why it is important to keep the strength of the coolant under check as well. This will determine that how much of the remaining fluid is water and how much is anti-freeze. Usually, a 50 50 mixture is recommended. But the volume of anti-freeze should not exceed 70%.

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How Much Coolant Loss is Normal?

Theoretically, over the course of 6 months 4% coolant loss should be considered normal. Another way of looking at this can be the height of the coolant column in your engine. If it drops 0.4 inches every 6 months then there are no leaks in your engine apparently.

As pointed above as well that car coolant is a fluid, and it is bound to evaporate. Due to the open-loop operation of most cooling systems, some part of the coolant is lost. The continuous exposure to high temperatures is also responsible for the evaporation of coolant.

In a 50 50 mixture of coolant and water, 3% loss after every 6 months means that your car will run out of coolant in 6 years. But it is advised to refill the coolant after every 2-3 years to keep the engine up and running.

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Why Does a Car Coolant Evaporate too Much?

Your car coolant should not evaporate more rapidly than the above-mentioned indicators. If it does then you should look for the reasons behind it. The most common culprit for too much evaporation of car coolant is overheating. Overheating causes too much loss of coolant which leads to its lower levels.

If you trace down any reason for the evaporation of car coolant then ultimately it will come down to one thing. That is the overheating of the engine. We will analyze this statement in the next section where we will discuss various reasons for too much evaporation of car coolant.

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Other Reasons why Car Coolant Disappears

Other than the major issue of engine overheating, potential reasons for too much coolant loss in a shorter period of time are:

  1. Radiator Leakage
  2. Internal Leakage
  3. Worn Out Head Gasket
  4. Faulty Radiator Cap
  5. Failed Water Pump
  6. Leaked Hoses
  7. Thermostat Problems
  8. Cooling Fan Failure
  • Radiator Leakage: Any leakage in the radiator will mean that water and coolant both are getting lost continuously. As a result, the engine is overheated and the rate of coolant loss is even more accelerated.
  • Internal Leakage: Internal leakage in the engine is also very well possible. A misaligned ring or seal can be a nasty problem. Since, such slight issues can lead to the accumulation of coolant in these locations, leading to its loss.
  • Worn Out Head Gasket: Due to the overheating of the engine, the head gasket comes in miserable condition. This often causes the gaskets to blow or wear out at the least. The coolant gets into the engine through this opening and is lost as a result.
  • Faulty Radiator Cap: Radiator cap is an extremely sensitive component. It is responsible for maintaining a specific coolant pressure inside the reservoir. In addition to that, it also ensures the optimum coolant levels. A faulty radiator cap can lead to rapid evaporation and coolant loss.
  • Failed Water Pump: The water pump is responsible for circulating the water around jackets in the engine. The failure of the water pump can often lead to overheating of the engine. This puts extra strain on the coolant and its evaporation is accelerated as a result.
  • Leaked Hoses: Leaked hoses are responsible for pressure loss in coolant reservoirs. This undermines the ability of coolant to reach all designated places. Which increases the local temperature and as a consequence coolant is lost.
  • Thermostat Problems: Thermostat problems are very common in cars. They lead to the overheating of the engine. This compromises the operation of the cooling system as well. The issue of overheating also causes coolant loss.
  • Cooling Fan Failure: A cooling fan is a big aid in controlling the engine temperature. When a cooling fan fails the engine temperature is raised. This puts extra work of removing excess heat onto the coolant. Which might lead to its excessive evaporation.