Car Coolant Blowing Out Of Reservoir – Causes & Solutions

Car Coolant Blowing Out Of Reservoir – Causes & Solutions

Your car coolant could be blowing out of the reservoir due to various reasons. These include a faulty cooling fan, a broken head gasket, and more.

Car Coolant Blowing Out of Reservoir GÇô Causes & Solutions

You don’t want to guess the problem only to realize later that you were long!

Causes Of Your Car Coolant Blowing Out Of The Reservoir

When you notice that your car coolant is blowing out of the reservoir, you need to act fast. Driving a car that an engine is overheating can be very dangerous.

But before you go rushing to do repairs, first identify the primary cause. You can do this by placing large cardboard below your engine overnight.

In the morning, it will be effortless to locate the position of the leak. Here are the various causes of the leak.

A Blown Head Gasket

The work of a head gasket is to prevent the coolant and the oil from mixing. It does this by sealing the internal combustion process.

The position of the head gasket is between the engine block and the cylinder head. Due to its position, it has to deal with very high and cold temperatures.

In time the impact of these temperatures will be felt. Leaks will occur in the head gasket leading to it blowing.

It will now be impossible to separate the coolant and the engine oil. Overheating occurs when this happens, causing your car coolant to blow out the reservoir.

Water Pump Failure

The water pump ensures the coolant is circulating throughout the cooling system. The water pump location is at the lower hose of the radiator.

Sometimes the hose connection becomes loose or corrodes. External damage to the water pump may cause it to leak.

Your engine will overheat when the water pump can no longer move the coolant. When this happens, the chances are high that your car coolant will blow out the reservoir.

A Hole In The Radiator

Over time your car’s various parts will tend to wear out.

Rust and sediment will collect and eventually cause holes in the radiator. When your radiator erodes, it will cause a leak.

A leaking radiator will make your engine overheat. Overheating the engine will cause your car’s coolant to blow out the reservoir.

The Car Expansion Tank Has A Problem

Next to your engine is a plastic container known as an expansion tank. The expansion container receives coolant to and from the radiator as the engine heats up and cools down.

The expansion container is connected to the radiator by a rubber hose.

Over time the plastic container and other parts will weaken due to temperature changes. Eventually, the plastic may crack, or the cap leaks, allowing the coolant to escape.

The rubber hose may also deteriorate, causing the car coolant to blow out the reservoir.

The Radiator Cap Is Leaking

A radiator cap is responsible for keeping a tight seal on the radiator. Because the radiator is highly pressurized, the cap needs to keep the cooling system at the correct pressure.

With time the cap may wear out, allowing the coolant to escape.

A Faulty Cooling Fan

The work of the cooling fan is to keep the radiator cool when the car is not moving. The cooling fan is connected to the radiator through a mesh of wires.

Unfortunately, over time these wires will tend to corrode. When that happens, the radiator will overheat.

The leading causes for a faulty cooling fan are broken wires, a bad relay, or a broken fuse. All these can lead to your car’s coolant blowing out the reservoir.

Car Coolant Blowing Out of Reservoir

Solutions For When Your Car Coolant Blows Out Of The Reservoir

When you identify the cause of your car coolant blowing out of the reservoir, go ahead and look for a solution.

By giving you the following solutions, you will find out the problem with your car.

Regular Maintenance

When running regular maintenance for your vehicle, you will avoid some problems.

Make sure that you change the coolant in your radiator. Old coolants turn acidic and begin to corrode the aluminum in your radiator.

Regular maintenance also makes it possible to detect when other parts like the hoses deteriorate and need repairs.

If you don’t take your car for regular maintenance, something like your car coolant blowing out reservoir will happen.

Buy Gasket Sealer

Once you realize that the reason for your car coolant blowing out of the reservoir is a blown gasket, the best solution is to replace the gasket.

But it is very costly, and you may not be in a position to fix it. Then the second-best thing is to seal it temporarily.

Buy a good head gasket sealer and pour it into your radiator. With the heater and the fan on high, run the car for 15-30 minutes.

The particular sealant chemical will fit in the cracks and the gaps of the head gasket. The repair will be complete once they harden.

Replace The Water Pump

It is good to note that a good water pump should last for 60,000 to 90,000 miles. Once it hits these miles, the best thing is to replace it without waiting for it to fail.

When you see your car’s water pump leaking, you are advised to take your vehicle to the mechanics.

Diagnosing a spoilt water pump can be a very tedious process that will require a professional.

But a bad water pump is often better off replaced as it would be complicated to repair. A bad water pump can lead to your car coolant blowing out the reservoir.

Repair The Coolant Reservoir

You can quickly fix it when you discover that your car coolant has blown out of the reservoir. If the reason is a damaged coolant reservoir, get ready to repair it.

Go to the local auto spare store and buy a plastic epoxy.

Make sure your car has been turned off and the engine has cooled down. Drain the remaining coolant from the reservoir.

Remove the radiator cap and disconnect anything connected to it. Dump whatever coolant remained.

Clean the coolant reservoir thoroughly and allow it to dry fully. Mix your epoxy and apply to the area that leaked.

Let it set before returning the coolant reservoir to the engine bay. Make sure you fix back all the parts you had removed.


Your car coolant keeps your engine operating at the right temperature.

On cold days the coolant provides heat inside the car. It also keeps your motor working as efficiently as possible and has low emissions.

These are enough reasons to keep your car’s coolant from blowing out of the reservoir. Once you identify the causes, you can apply the appropriate solutions.

Maintaining a regular car maintenance schedule is wise to prevent your car coolant from blowing out the reservoir.

When most parts have problems, we have seen that they will eventually affect the coolant reservoir.