What happens when Coolant is Low

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The coolant in your engine plays a very vital role in keeping your engine running smoothly and efficiently. It assists to keep the engine operating at a consistent temperature, which helps to prevent overheating and engine damage. When the coolant level in your engine is low, it can cause a number of problems. Learn what happens when coolant is low.

One of the most common problems that can occur when the coolant is low is overheating. When the coolant level is low, there is less fluid to absorb the heat from the engine. This can cause the engine to overheat, which can lead to serious engine damage.

In this article, we will discuss what can happen if your engine’s coolant level is low and what can be potential reasons behind it.

What Happens If Your Car Runs Out of Coolant? 

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The following are the consequences of a car running out of coolant.

1. Air in the coolant system

Initially, there might not be any visible symptoms when the coolant level is low. However, as the coolant level decreases, air bubbles will start to form in the system. These air bubbles can cause the coolant to become less effective at absorbing heat from the engine.

2. Overheating Engine

What follows next is the most serious consequence of a car running out of coolant – an overheated engine. When there is not enough coolant to absorb the heat generated by the engine, the engine temperature will start to rise. If the engine temperature gets too high, it can cause severe damage to the engine components.

3. Blowing the head gasket

One of the many forms of severe damage that can be caused by an overheated engine is blowing the head gasket. The head gasket is a very important component that seals the engine block and the cylinder head. When it blows, it can cause coolant and oil to mix together, which can lead to even more engine damage.

4. Damaged Engine block

The engine block is the main component of the engine. It houses the pistons, connecting rods, and crankshaft. If the engine block is damaged, it can cause the engine to seize up, which will lead to a complete breakdown. 

5. Seized Engine

Then, finally, if the engine block is damaged or the head gasket has blown, the engine will seize up and stop working entirely. At this point, the only way to fix the problem is to replace the engine altogether.

Also Read: Can A Bad Coolant Temp Sensor Cause Rough Idle

Symptoms of Low Engine Coolant 

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In order to avoid the serious consequences of a car running out of coolant, it is important to be aware of the symptoms that indicate that the coolant level is low. Some of the most common symptoms include:

1. Dashboard warning light

One of the first signs that the coolant level is low is when the dashboard warning light comes on. This light indicates that there is a problem with the engine and its system.

2. Rising temperature gauge

You will also notice that the temperature gauge on the dashboard is rising. This is an indication that the engine is starting to overheat.

3. Automatic engine cut-off

In some cases, the engine will automatically cut off when it starts to overheat. This is a safety feature that is designed to prevent further damage to the engine.

4. Poor fuel economy

You might notice that your car’s fuel economy has decreased in some cases. This is because the engine has to work harder to maintain a normal operating temperature, which uses up more fuel.

4. Internal heating system not working properly

If your car has an internal heating system, you might notice that it is not working as well as it used to. This is because the heat is not being transferred properly.

5. Distinct sweet smell

Coolant has a distinct sweet smell, so if you notice this smell inside your car, it is an indication that there is a leak in its system.

Also Read: Can You Mix Coolant Brands

Is it safe to drive with a low engine coolant level?

Driving with a low engine coolant level is not safe and can lead to serious engine damage. If you notice any of the symptoms of a low coolant level, it is important to take your car to a mechanic as soon as possible.

Causes of Low Engine Coolant Level 

The following may be causes of a low engine coolant level:

1. External coolant leak

Most commonly, a low coolant level is caused by an external leak. This can be due to a leaking radiator hose or a cracked radiator.

2. Faulty intake manifold gasket

When the intake manifold gasket is faulty, it can cause a coolant leak. This gasket seals the connection between the engine and the intake manifold.

3. Faulty head gasket

A faulty head gasket can also cause a coolant leak. The head gasket seals the engine block and the cylinder head.

4. Faulty radiator cap

A faulty radiator cap can cause the coolant to overflow and be lost. The radiator cap is responsible for maintaining the correct amount of pressure in the cooling system.

5. Faulty EGR cooler

The EGR cooler is responsible for cooling the exhaust gases that are recirculated back into the engine. If it is not working properly, it can cause the coolant to overheat and be lost.


Low coolant levels can cause serious engine damage. It is important to be aware of the symptoms of low coolant levels and to take your car to a mechanic as soon as possible if you notice any of them. In order to avoid low coolant levels, it is important to check the level regularly and to make sure that there are no leaks in the system.

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