My truck has another leak to add to the others. This new leak is one I can’t ignore. A continuous drip. Upon closer examination, it was not oil nor ATF that was leaking; this leak smelled sweet, that sweet sticky smell of antifreeze. The engine’s coolant system was compromised. Most coolant leaks are not easily noticed, because they are small cracks in hoses or in the radiator. A common sign of a leaky coolant system will be a low coolant level. The easiest way to check the system’s coolant level is to take the radiator’s cap off and see if the coolant comes up to the top of the radiator.
Do this with the engine off and when the engine has had at least an hour to cool off. If the radiator cap is removed when the engine is hot, it can result in serious injury and third-degree burns. The radiator cap is located at the front of the engine bay. To remove it, push down and turn it counterclockwise. With the cap removed, look down into the radiator; sometimes it is helpful to use a light to see the coolant level within the radiator. A healthy system should have coolant up or right to the neck of the radiator. A system that is leaking coolant will read lower into the radiator and in severe cases, no coolant will be present in the radiator. Some vehicles use a coolant reservoir that is transparent. They will have a full measurement line made into the side that makes checking the engine coolant level simpler.
Getting started
If you noticed your coolant does not come up to the top of the radiator or the reservoir tanks full line, you may have a coolant leak. To check your vehicle for a coolant leak you will need the following:
• A pressure tester and corresponding radiator/overflow tank adaptors
• A jug of water
• A drain bucket
• A flashlight
The easiest way to see where the coolant is leaking from is to use a pressure tester. This tool creates pressure in the system and forces the coolant to be pushed out of the system, indicating the leaking component. A pressure tester can be loaned to you from AutoZone for free. The tool should come in a kit with several adaptors that can be used on almost any vehicle type and manufacturer.
The first step is to park the vehicle on a level surface. Pop the hood and locate the engine’s radiator cap or the overflow tank cap depending on the vehicle. Refer to the owner’s manual if you are unsure. My truck uses a radiator cap, it is located on the driver’s side of the engine bay towards the front of the truck.
Touch the top of the cap quickly with the palm of your hand. If it is cool to the touch, you can proceed. If it is hot or warm, let the vehicle sit until it is cool to the touch. With the radiator cap cool, push down and turn the cap counterclockwise to remove it. The same goes for a coolant reservoir cap.
Next, fill the radiator with water until it is full. Then locate the correct pressure tester adaptor for your application. The correct adaptor should twist tightly onto the radiator or coolant overflow tanks threads. When you have located the correct one, install it onto the radiator by pushing down and twisting clockwise until it is tight. My truck doesn’t need the adaptor because the pressure tester is the correct size.
Now, you can install the pressure tester onto the adaptor. This will twist on the same as a radiator cap. It will have a rotating spring-loaded arm located on top. With it twisted firmly onto the adaptor, hold the base of the tester and rotate this arm. It should lock into place. This may take several attempts. Now it is time to pressurize the coolant system.
To create this pressure, you will pump the tester’s handle up and down several times. The tester will have a small gauge that indicates the amount of pressure you are creating in the system. Do not exceed the red line at the end of the gauge as this could cause other coolant system components to fail. After the pressure is built watch the gauge. Does it lose pressure quickly? This could indicate a large coolant leak. Does it lose pressure over the course of a few minutes? This may indicate a small leak. Or does the gauge remain the same constantly for more than fifteen minutes? This may indicate there is not a leak. Re-pressurize the coolant system. Use your flashlight to look under the vehicle. If there is a leak you should notice a steady stream of coolant leaking out. Place your drain bucket under the vehicle. Coolant is harmful to the environment and it should be disposed of properly. Many mechanic shops can take the coolant off your hands for a small price. You can also reuse the coolant.
Work your way up following the trail of coolant. Be sure to pay close attention to the radiator, radiator hoses, heater hoses, water pump and thermostat housing. You should notice where the coolant is coming from. My truck is leaking behind the water pump where the timing chain meets the engine block. In this case, the leak is very obvious.
