Radiator Warning Signs

car radiator

Radiator Warning Signs

When you see the temperature gauge on your car go up to “high” or the warning light is on, you may have a problem in your cooling system, which may be due to a leak in your radiator or in another component.

To confirm the leak is coolant, which is often called antifreeze (it’s actually half antifreeze and half water), look at the level of coolant in your overflow tank. If it’s low or empty, then check the level of coolant in the radiator, but only when the engine has cooled down.

Some radiator leaks can be spotted by a puddle on the ground beneath the radiator, but other leaks are more difficult to find. You need to thoroughly look all around your radiator, not just view it from above. Look at all the seams and get under the car so you can see it from the bottom. Road debris being thrust up into the radiator can cause holes as well as rust and corrosion, which all cause leaks.

You can recognize antifreeze by its colours. It comes in yellow, pinkish red, and green, often has a sweet smell and feels a bit slimy. If you don’t see any coolant seeping or dripping out, look around for rust spots, stains or tracks on the radiator. These can help you spot where it is leaking.

If you don’t find any signs of leakage on the radiator, the leak may be with the cooling system, which includes the water pump, radiator cap, hoses going to the engine from the radiator, overflow tank,  thermostat, engine block, heat exchanger (small radiator blowing hot coolant through the dashboard to heat the cabin) or others. The leak could also be coming from a blown gasket located between the engine block and cylinder head, which would allow coolant to seep into the combustion chambers, something a mechanic would immediately need to take care of.

After doing all this looking around and you still can’t locate the leak, have your car checked out by a professional. Coolant can easily escape under pressure as steam while the car is running, without leaving a trace.

car radiator

Checking & Adding Radiator Fluid

Your car’s entire cooling system is built around the radiator and also includes the water pump, hoses, belts, fan, thermostat, and sensors. Its job is to move coolant around the cylinder heads and valves, absorbing their heat before returning the coolant to the radiator to safely dissipate the heat. This only works if there is a certain level of fluid in your radiator, meaning you need to always be checking the level of coolant and add more whenever necessary.

Step 1 – Checking the Level of Radiator Fluid

    • Drive your car a short distance and then park it on a level surface. The best time to check the coolant or antifreeze level is when the engine is lukewarm or cool, not when it’s hot or cold. If you’ve been driving for some distance, turn the engine off and let it sit for a few hours so the engine cools down enough.
    • Never check the fluid level in the radiator when the engine is running nor when the engine is still hot.
    • Lift the hood.
    • Look around for your radiator cap. If you have a newer car the cap should be labeled. It is a pressurized cap, which should be near or on top of the radiator. If you can’t find it, your owner’s manual can help you.
    • Using a rag to protect your hand from being scalded. The overflow and radiator caps will be hot from the coolant having absorbed the engine heat.
    • You will need two hands to twist off the cap, placing your pointer and middle fingers on one hand together, pressing down on the cap while simultaneously twisting the cap off using the other hand. This prevents the coolant from bursting through in case the system is still under pressure.
    • Once the cap is off you can look into the radiator to check the fluid level. It should be close to the top. There might be a “Full” etched into the metal, which indicates where the level should be when filled up.
    • Look for the overflow tank of your radiator and remove the cap. Most modern cars come with an overflow tank so that radiator fluid can expand and flow into it when it gets really hot. There should be very little fluid in this tank, if any. However, if you see that the level of coolant in the radiator is almost empty, while the overflow tank is nearly full, long after you’ve driven the car, take your car in for service immediately.
    • You need to check your coolant’s freezing and boiling point. Over time, your radiator fluid’s ability to absorb and then dissipate heat wanes. You can use an antifreeze hydrometer to test out the freezing and boiling points. Add more coolant as needed, using a funnel to avoid spillage. For most driving conditions, mix antifreeze with distilled water 50/50 or half antifreeze with half distilled water. In severe weather, you can go up to 70% antifreeze with 30% water, but not any higher.
    • Never add coolant while the engine remains warm.

Step 2 – Testing the Coolant Protection Level

    • Give the hydrometer bulb a good squeeze to force the air out.
    • Insert its rubber tube down into the coolant.
    • Unsqueeze the bulb to draw the coolant into the hydrometer to float the needle or the plastic balls within the hydrometer.
    • Take the hydrometer out of the coolant.
    • Look at the hydrometer to determine the freezing level or boiling point level. If your hydrometer has a needle, it should be pointing to a specific temperature of range of temperatures. If it has a bunch of plastic balls, the number of floating balls will tell you how well your antifreeze is protecting your engine from freezing-up or boiling over. If you have an insufficient level, you will need to add coolant or totally replace it.
    • It is best to test your coolant protection level every spring and fall, but more often if you live and drive under extreme weather conditions.

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