Hey, Why is My Car Leaking Coolant?
Is Your Car Leaking Coolant?
The coolant leak is commonly caused by a crack in the radiator, the heater core, or the coolant reservoir. The radiator commonly cracks if it’s old or if it hits an object. The leak can also be caused by a loose coolant hose, a faulty water pump, or even a blown head gasket.
Coolant is your vehicle's first protection against engine overheating; you're left vulnerable if it leaks. Checking your coolant levels regularly is a good practice since many leaks can strike unexpectedly. So, if you notice the levels dropping abnormally, something might be wrong.
Your cooling system requires routine maintenance. Coolant can turn acidic and eat away at gaskets and seals, causing dangerous leaks if neglected. In addition, factors such as temperature changes or simple wear can cause leaks.
While coolant does incredible things for your car, it is a toxic substance. It can poison animals and waterways if it leaks from a vehicle. In addition, because coolant gets hot when it's working, it can also scald someone standing near a leak.
Let's Get To The Bottom Of It!
You may also see streaming coming from under the hood or notice the engine overheating.
The vibrations of driving, temperature fluctuations, and environmental stress around a radiator can cause wear on the seal that connects the tank that holds the coolant and the core. If a small leak develops, the coolant dries on the radiator. This dried coolant looks like corrosion and may show blue or red discoloration, depending on the color of the coolant.
You may also notice the engine overheating or feel a rough idle.
The bearings and seals inside the vehicle's water pump degrade with use. If coolant isn't maintained, it becomes acidic with age, speeding up the wearing process on these seals. In addition, when the seal between the pump and coolant leaks, it creates a weep hole that lets any coolant out before it affects the pump's bearings. This causes the leak to run down the engine block, which can be seen as a crusty, discolored buildup of dried coolant. Depending on the tank's coolant type, it may be red or green.
You may also notice that the engine cranks long before starting. After the engine runs, you might see a small puddle of coolant under the car.
Coolant passages between the head gaskets connect an engine's combustion chamber to the valve chamber. These passages dissipate heat from the engine block and the heads. Engine overheating or acidic coolant can damage the head gasket. When these gaskets are compromised, gasses from combustion get into the coolant passages, causing the coolant to become superheated. Superheated coolant leads to the engine overheating and further wear on the gaskets. Coolant leaks into the engine's combustion chamber when the gaskets are badly damaged, which you'll notice as white smoke in the exhaust. That's the coolant burning with the vehicle's fuel.
You may also notice that the windows stay fogged even when the defroster is on or that the carpet on the front passenger side floor is wet.
Inside the air box in your vehicle's dash is the heater core. This circulates coolant so that your heater warms up the vehicle's interior. If the cooling system isn't maintained, the coolant turns acidic and can degrade the heater core. This can cause coolant to leak inside the vehicle. In addition, if coolant gets in the air box, it gets vaporized by air blowing over it and through your vents. You will notice this vaporized coolant as a sweet smell blowing through your heating and air conditioning vents.
You may also notice steam coming from under the hood or your engine is overheating.
The coolant reservoir is the highest point of the cooling system and is filled with half air and half liquid coolant. When a leak in the reservoir occurs, the coolant won't be low in the tank until several heat and cool cycles force enough out. It is at this point that the low coolant is visible.
You may also notice the "check engine" light is on or the "coolant temperature" gauge is running in the red.
The coolant hoses attach the engine cooling system to the radiator. Since they are made of rubber, they will become brittle over time and can crack, causing a leak. Flex from worn motor mounts can stretch the hoses as well. A band clamp attaches the hoses to the radiator or engine block. Wear over time and from temperature changes causes leaks. These leaks are most common after the vehicle cools when various components contract due to the temperature change. When your car is parked, it's cooling, and you will see the leak as evidence of this wear.
Find Professional Help
Vehicle Health Inspection Proof
Explore the following typical inspection results that show a potential cause for the symptom and select the one you believe is similar to your vehicle's issue.
- Leaking radiator
- Failing water pump
- Blown head gasket
- Heater core leaking
- Coolant reservoir leaking
- Leaking coolant hose
The proof image shows the crusty buildup of coolant as proof that the radiator is leaking.
A customer dropped off their vehicle upon noticing some corrosion on the radiator. They thought the car's battery exploded, causing the problem.
The technician did not notice anything about the customer's concerns on the test drive.
During the vehicle health inspection, the mechanic noticed a lot of dried coolant on the upper tank of the radiator. The technician tested the battery and found nothing about the customer's concerns.
The technician used a cooling system pressure tester to pressurize the cooling system. They pumped up the pressure to the suggested rating on the radiator cap. Upon inspection, the technician found a small crack in the upper tank of the radiator that was causing it to leak coolant under pressure. The radiator requires replacement.
1/6Typical Fixes to Address the Cause(s)
The following chapters bases themselves on experiences from our auto repair shop; we'll describe related problems' causes and fixes.
The AutoTechIQ ranking for Safety, Cost Avoidance, and Environmental Impact is
Vehicle Symptoms
Below are just a few examples of typical Symptoms and Fixes your car might be experiencing
Other things your auto repair shop might talk about:
Engine oil. Coolant leak fix. Car's engine. Coolant tank. Hose connection.