How To Find and Fix Coolant Leaks

Car, truck, and SUV engines operate at hot temperatures. In fact, after running for just a few minutes, your vehicle’s engine temperature likely climbs to between 195- and 220-degrees Fahrenheit. Because that sort of extreme heat can damage engine components over time, your vehicle has a cooling system. Your car’s cooling system works by pumping fluid through the engine, where it picks up heat. The fluid then moves to the radiator, where it cools before starting the cycle again. As such, if you have a car leaking coolant, you must act quickly to find and fix the coolant leak.

Understanding Coolant Leaks

Coolant is an essential fluid. That is, if you do not have the right amount of fluid, you are asking for serious trouble that may include substantial engine damage. As such, you should routinely check your car’s coolant levels. If you regularly find that you are adding new fluid to your system, there is a good chance you have a coolant leak.

How to Detect Coolant Leaks



Your vehicle’s head gasket seals the space between its cylinder head and engine block. If the head gasket fails, coolant, and engine oil may mix. You may also notice that coolant is leaking from the bottom of the engine and dripping onto the ground. Either way, a blown head gasket can be disastrous for your engine.


Your heater core is essentially a small radiator that disperses heat into your vehicle’s passenger cabin. While you cannot see the heater core, it may develop a coolant leak. If it does, fluid may accumulate in the plastic housing on the bottom of the heater core.


Coolant may move through many different hoses under your vehicle’s hood. If one of these hoses develops a crack or hole, coolant may leak.


Hoses in your vehicle’s cooling system must connect to different components. Some connections may have hose clamps, while others may attach on their own. Any place a hose connects, though, is prone to springing a coolant leak.


Modern coolant has anti-corrosive agents that help protect your radiator from damage. Still, sometimes radiators develop holes. If your vehicle’s radiator has one, you may notice a leak in front of your engine.

Coolant leaks are serious business any time of the year. That is, even though coolant is commonly called antifreeze, it is essential year-round. Therefore, if you have a car leaking coolant, you must take the leak seriously. Fortunately, finding a coolant leak may not be as difficult as you may think.

Finding Coolant Leaks

Often, finding a coolant leak is simple, as you can see fluid dripping from beneath your vehicle’s hood. You may also notice bubbles in the coolant reservoir or at a hose connection. You must be careful when checking fluid levels, though. If the engine is not completely cool before you remove the radiator cap, you may suffer a serious burn from escaping steam or hot coolant. Therefore, you should never open the radiator cap or the coolant reservoir when your car’s engine is hot.

Typically, a coolant leak presents itself in just a few ways. For example, your vehicle’s engine may overheat. If this happens, the temperature gauge on your instrument panel is likely to move upward, perhaps into the red zone. You may also notice steam coming from under your hood. Or, your vehicle may stall. If your car has a low-coolant indicator light, it may also illuminate.

To locate a coolant leak, first look for puddles of coolant beneath your vehicle. If you see any, you probably have fluid dripping from somewhere in the system. With the car’s engine running, look under the hood to see if you notice any fluid flowing out. If you do, trace the fluid to its source. Do not forget to check hose connections and components for leaks. Allowing your vehicle to climb to normal operating temperature and turning on the air conditioner increases pressure in your coolant system. This procedure may allow you to more easily detect a coolant leak.

If you cannot see a leak but you are losing coolant, you may need to perform a coolant pressure test. A pressure tester is a hand-held tool that allows you to gauge the pressure inside your cooling system. If you have low pressure, you probably have a leak somewhere.

Fixing Coolant Leaks

The best way to fix a coolant leak is to track down the location of the leak and repair the old, damaged, or ineffective part. For example, if you have a cracked hose, replacing it is the most effective way to stop your leak. Some components naturally wear out over time. As such, replacing hoses, the radiator cap, or the reservoir tank may eventually become necessary on older vehicles.

You certainly should keep an eye on hose clamps. With ordinary engine movement, clamps can work their way loose. Checking to see that clamps are always sufficiently tight may prevent a leak from forming in the first place.

If your leak is because of something more serious, such as a blown head gasket, your fix is not so simple. While replacing a bad head gasket is the best way to go in the longterm, such a replacement is very labor intensive and expensive, and you may be able to use a sealant for less serious cracks or breaks. Sealant products may also work for holes in the radiator. If you are looking at a costly repair or replacing, trying a sealant first may be the way to go.

Finishing Your Project

Even though you may never want to have to deal with a car leaking coolant, the problem is more common than you may think. You cannot ignore coolant leaks or any other issue with your vehicle’s cooling system. Now that you understand how to find and fix coolant leaks, you are ready to tackle your project. To finish it successfully, always choose high-quality replacement parts and the right coolant for your vehicle. With some planning and a bit of effort, you can stop your vehicle’s coolant leak and extend the life of its engine.

Do you need a more in-depth look into your vehicle to help you with your project? ALLDATA, the leading provider of automotive repair information, is now providing DIYers with the same information that the pros use with ALLDATAdiy’s single-vehicle subscriptions.

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