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Is It Normal For Coolant Level To Drop

Is It Normal For Coolant Level To Drop?

For a car to operate stably for a long time, it is indispensable for engine coolant. The substance has the effect of reducing engine temperature in summer and increasing engine temperature in winter.

However, for some reason, the coolant level can drop. So, is it normal for coolant level to drop? The answer is NO. Because the liquid level drops suddenly or exceeds the norm, it will be dangerous for the car engine.

So, what are the possible causes for the coolant level to drop? You can refer to 3 common reasons below.

What Causes Coolant To Decrease?

What Causes Coolant To Decrease

Leaking coolant will cause your engine to overheat. This directly affects the car’s performance; it costs you a small amount of money to fix the problem. In addition, using the wrong coolant or using a vehicle with low coolant levels will also cause your engine to overheat.

Most of the above reasons are subjective reasons from users. At the same time, there are 3 other common causes of low coolant levels:

  • Broken gasket
  • Corrosion/damage tank cap
  • The radiator hose is worn/damaged

# 1: Broken gasket

The damaged gasket is the first objective reason for the engine to overheat. When the front gasket is loose, the coolant will leak and evaporate to the outside. Its consequence is the failure of the head gasket. The coolant then enters the combustion chamber and ignites, damaging the exhaust system and catalytic converter. White smoke from the engine will appear when the head gasket explodes, causing damage to the engine block or cylinder head.

# 2:  Corrosion/damage tank cap

As you know, the radiator cap is to maintain the coolant level and tank pressure to ensure that the coolant can move steadily through the engine system. When the radiator cap fails, the coolant escapes, and the pressure drops in the reservoir.

The warning light on the control panel will light up. The best way to limit this problem is to check the tank cap once a year to minimize the possibility of damage and tearing of the rubber pad.

# 3:The radiator hose is worn/damaged

Because the radiator pipes are located quite close to the engine, they are often exposed to high-temperature environments when the car is operating. At that time, these tubes may crack and break after a period of use.

That causes the coolant to spill out of the system, causing a drastic drop in the liquid level. At the same time, the constant spillage of the coolant will affect the engine head gasket.

Is It Normal For Coolant Level To Drop?

Is It Normal For Coolant Level To Drop

Mostly, the drop in liquid level is the result of problems related to the cooling system.

In order for the car to operate stably, without overheating, it is necessary to have a harmonious combination of parts in the cooling system. The main parts include a water pump, coolant, and cooling fan.

When the pump cannot push the coolant to the engine, a host of negative consequences can result. Typically degrades the coolant and destroys the engine.

In addition, the radiator housing is a coolant outlet located in the engine block or on the cylinder. When the coolant flows from the engine to the radiator, it passes through the thermostat. If the coolant gets stuck in the closed position with the housing, it will cause blockages and leaks under the car.

Currently, many people have asked the question, “Does coolant decrease over time?” The answer is yes. The gradual loss of coolant is a common phenomenon in all cars.

Does Coolant Decrease Over Time? If Yes, How Much Is Normal?

A small amount of coolant may evaporate because the cooling system is not a closed system. Over time, the coolant flowing in the engine and radiator after being exposed to high temperatures will naturally become unbalanced.

From there, the coolant will evaporate without any leakage. In addition, as the engine ages, the coolant will have a greater evaporation rate. On average, after 4 months of use, the coolant will be reduced by 0.25” in good engine operating conditions and with no leaks.

In addition, when evaporating, some of the elements in the coolant will turn into water vapor. If there is too much steam in the engine, it will reduce their efficiency. Therefore, you should clean the cooling system after a few years of use, including replacing the new coolant.

Some Frequently Asked Questions

Q: How much coolant loss is normal?

Usually, the liquid level will drop by at least 0.25% every 4 months without damage or leakage. Therefore, you need to pay attention to the drop cycle of the coolant so that it can be replaced when necessary. On average, you will need to change the coolant once a year.

Q: Why is my coolant low but no leaks?

There are 2 cases. The first cause is due to the normal evaporation of the coolant. The second cause can be due to some other vital issues such as:

  • Head gasket exploded
  • Broken cylinder head
  • Damaged cylinder bore
  • Leaking manifold
  • The hydraulic lock has a problem

Q: How often should you top up coolant?

The timely refilling of coolant will protect the engine from overheating. So when do you need to refill the coolant? You can rely on time or mileage. If it’s time, you can supply the coolant after 1 year under the condition that the cooling system is working well and there are no leaks.

As for mileage, you’ll need to refill with coolant once your car has at least 30,000 miles on it. If your vehicle is older, the mileage may be less.


Hopefully, the article will help you better understand the possible causes of coolant drop. We can divide it into two main groups of factors: subjective and objective. Emotionality is due to the normal thermal evaporation of the coolant during use.

Objectively, the parts that work directly with the coolant have problems: gaskets, tank caps, or radiator hoses. Therefore, you need to pay attention to the coolant level because the engine will overheat if they are too low.

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