Coolant leaks when car isn't running

You might think that coolant is more likely to leak out of the car when the engine is running, but this isn’t the case. Coolant can leak more easily when it circulates in the engine's system. Is it possible to have coolant leakage when your car isn't running?

Damaged hoses or radiator caps, bad radiators, defective pumps, and coolant leaks can cause the car to stop running. It’s also possible that there is a bad heater core or a blown head gasket. Bad intake manifold gaskets could be the cause. 

We will examine the reasons coolant could leak while the engine is not running. You will be shown simple solutions. 

Coolant Leakage Causes While Your Car Is Running

1. Bad Heater Core

Hot coolant gets pumped into the engine through the system’s heater core. When you turn on the heater, the heat generated by the system is blown into your vehicle via the HVAC vents.

Bad heater cores can cause heat loss and make it difficult to get heat in the system. There might be leakage around the drivers or passenger seats, and under the car. 

2. Hoses that are damaged

Broken hoses can cause leaks when an engine is in use. The pressure within the engine can increase or decrease depending on what the hole is.

Hoses may become fragile and wear over time. This is why it's important to inspect them regularly. Unchecked heat or constant pressure could cause increased wear. 

3. Radiator Cover or Radiator Bad

It is necessary to protect the coolant system from the elements. The radiator cap also regulates the temperature.

The cap can be damaged and coolant could leak, resulting in lower radiator levels. Due to the increased pressure within the hoses, coolant could leak from the reservoir and cause engine damage.

High speeds can also cause cracks or damage to the radiator, such as corrosion and stones.  

RELATED: 6 Symptoms of a Bad Radiator Cap (& Replacement Cost)

4. Head Gasket

A blown head gasket could be the reason coolant is leaking into your engine oil, or combustion chamber. Head gaskets are responsible for keeping oil and coolant separate.

As coolant leaks into the system, it’s no longer able to keep the engine cool. This problem occurs when the engine is running and when it’s off, but running the engine is more dangerous since the motor will start overheating. 

Bad head gaskets can cause coolant loss. You will be able to see where coolant is leaking between the block of the engine and the head.

RELATED: 7 Easy Steps to Check if Your Head Gasket Is Blown

5. Defective Water Pump

A water pump that is not working properly can cause a coolant leak. The water pump’s job is to push the coolant through the hoses smoothly. 

The coolant will not flow as it should when the water pump fails. The engine can also be affected by this issue. 

6. Bad Intake Manifold Gasket

You will find the intake manifold gasket at the point where it connects with the engine. A bad gasket could cause coolant to leak below the vehicle.

You will be better off if you fix it as quickly as possible. It could cause serious problems when your engine runs. 

RELATED: 5 Causes of a Coolant Leak (& How to Fix it)

Coolant Leakage: What to Look for?

1. Radiator/Cap

You should first look around your radiator for any leakage. It is possible to clear the radiator from leaves, dirt, and debris in order to find the source of the coolant. 

To check if the cap is cracked or damaged, you should inspect it as well. You should secure it to your radiator in order to prevent any leakage. 

2. Hoses

You should inspect all hoses in the system. Coolant should not drip off a torn or damaged hose. The location of the leak will determine if the coolant is leaking.

Also, you should look out for cracks on the hose's surface. Even if there isn’t a hole yet, coolant could easily be seeping through the crack. 

3. Unter Fahrzeug

Take a look underneath your vehicle to find any leaking coolant. The color of the coolant will vary depending on which type you choose. 

You can determine the source of the coolant leak to get a better understanding of which part may have gone wrong. Coolant may have leaked onto parts if you drove with it. For a more accurate idea, clean the undercarriage thoroughly and examine it once again. 

4. Thermostat Core

Have a look at the flooring under your passenger seat. The heater core could be responsible for coolant spots or other problems. 

If the heater core becomes damaged, fluid can be leaking under the car's side. The engine could also heat up if it has lower levels. 

5. Below the water pump

Water pumps can be driven by either the timing belt or serpentine belt, depending on which car you have. Look for any leaks beneath the pump, if the serpentine belt is used.

The timing belt may make it difficult for you to view the pump if it is driving by it. You may have to pull the timing belt cover off to be able to look at it. If there's a leak underneath the crankshaft pulley, and the pump drives by the cam belt there's a good chance it's the pump.

6. Head Gasket

It’s not as easy to see a leaking head gasket. To discover this issue, you will need to check the coolant fluid and oil to see if there’s any contamination. If you find coolant leakage, check the area between your engine block and your head.

How to Repair Coolant Leak

Coolant leaks can be fixed depending on the cause. If the heater core has been damaged, it is possible to replace it. A heater core replacement will typically cost $500-$1000 for parts and labor.

The cost of damaged hoses will vary depending on the location and difficulty in removing it. There are occasions when the clamp is loose and a hose leaks. You can tighten the clamp or replace it if this happens.

A radiator cap replacement is one of the most affordable options. A new radiator cap can be installed in minutes and costs only $10-50.

You will have to replace the water pump if it has stopped working. A new water pump replacement could cost $350 to $800, but there’s the option to purchase a remanufactured water pump to save a little money. 

If you need to replace the intake manifold gasket, the part itself doesn’t cost a lot of money. The cost of the part is usually between $20 and $100. However, it’s not an easy part to replace, so the labor could easily add another $200 to $400 unless you can swap it out at home.

It is the best option to change your head gasket. A new head gasket can cost anywhere from $1,500-$2,000. However, if you don’t get the blown head gasket fixed promptly, there could be severe engine damage occurring as the motor continues to overheat. You should not leave this problem unattended.

What Can I Do if My Coolant Leaks?

Your car may seem to run fine despite the coolant leak, but you shouldn’t drive it. As the coolant leaks, the engine temperature won’t be properly regulated. 

Permanent damage can be caused by engine heat. A small leak could quickly turn into a major problem, even if the engine is not in use. If you leave your home, even a tiny hole in the hose may become large enough to dump all coolant.