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Engine Cooling System Repair

The last thing you want to have happen to your engine, especially on a hot summer day, is to have it overheat. Overheating can cause the metal of the engine, oftentimes aluminum, to swell, expand, warp and even crack, breaking the engine and either rendering it useless or ruining its performance. The easiest way to avoid an overheating engine is to check your driver's console and look for the engine temperature dial to make sure it is not moving toward the red. Regular maintenance checkups help to keep your engine from overheating, either doing it yourself or scheduling an appointment with a 12th Street Auto repair mechanic. With financing available, there is no need to wait or worry about paying for your car's next repair.

ASE and AAA Approved Engine Cooling System Technicians

Expert cooling system technicians are happy to repair and help maintain your engine’s longevity. One way to keep it running is by ensuring that the cooling system prevents the engine from overheating. Sometimes, special equipment is required in order to service an engine’s cooling system, which are owned by auto repair shops like 12th Street Auto Care Center.

Engine Cooling System Components

In order for your engine to stay cool enough as to not overheat and warm enough as to run efficiently and cleanly, a cooling system that pumps a chemical liquid mixed with water through the engine and around a circuit of hoses and pipes is necessary. People have tried different mixtures, but nothing has worked as well, so far, as antifreeze, consisting mostly of ethylene glycol or sometimes propelene glycol. It is also known as coolant. Coolant serves to cool and stabilize the engine’s temperature and lasts for up to three years or more. But in order to pump coolant throughout the engine, your engine cooling system needs a water pump.

Engine Water Pump

A water pump, also known as a coolant pump, is a basic centrifugal pump that circulates coolant throughout the engine block and the hoses connected to it, while the engine is running. The water pump is the heart of the engine cooling system. It is driven by the engine drive belt via a pulley system, which is connected to the crankshaft. When the engine first starts up and the coolant is circulating through, it does not continue through the whole system until the thermostat allows it.

Car Thermostat

After passing through the engine block, the coolant reaches the car’s thermostat. The thermostat is controlled either by a computer or by wax contained within the cylinder of the thermostat. When the coolant first reaches the thermostat, it is probably closed, because it has not reached a high enough temperature. With the thermostat closed, the coolant is looped immediately back to the water pump of the engine cooling system and cycles through the engine block and back to the thermostat. But, if the coolant is hot enough, the wax will melt within the cylinder, or the computer will send a signal to the valve, and the thermostat valve will open, allowing coolant into the radiator to be cooled.


After passing through the thermostat, the coolant flows through a hose and into the radiator. The coolant will then travel through the core tubes of the radiator in order to cool off. Due to its aluminum design, the heat is conducted through the wide surface area of the radiator’s cooling fins, and then it is transferred to the air that is flowing through the radiator. A radiator fan helps to better control the air flow, which in turn helps the cooling process. The radiator cap, due to pressure in the radiator, increases the boiling point of the coolant. Should the pressure become too much, the radiator pressure cap will allow the coolant to overflow into the radiator overflow tank, or coolant reservoir. After the coolant has lost enough heat, it is recycled back into the engine cooling system.

Coolant Reservoir

Overflow from the radiator travels through a hose into the radiator overflow tank, or coolant reservoir. Because of the design of the radiator pressure cap working in conjunction with the overflow tank, the engine cooling system remains a closed cooling system, allowing no air to enter it, making the cooling system more reliable and efficient. The collected overflow of coolant from the radiator will eventually cool off. Once this happens, the coolant is returned to the water pump and rejoins the cycle by a vacuum created by the decrease of temperatures within the cooling system. With the radiator and coolant reservoir being one way of expelling the heat from the coolant, there is another route that the coolant can take, which is through the heater core.

Heater Core

Much like a radiator, this smaller version, called the heater core, conducts the heat out of the coolant, aided by a fan, and into the vehicle’s cabin, which then heats the passengers. Once stripped of its heat, the coolant flows back into the water pump to rejoin the engine cooling system’s circuit.


Also known as antifreeze, coolant is the most integral part of the engine cooling system. Without it, the engine would overheat or freeze and more than likely break. Coolant, or antifreeze, is normally a mixture of ethylene glycol and water, or sometimes propelene glycol and water. Because of the chemical mixture, the liquid coolant is able to absorb the heat from the engine as it passes through the water jackets within the engine cooling block, and either travels directly back to the water pump, to the radiator or to the heater core, which transfers the heat of the coolant to the interior of your vehicle. And, because of the chemical mixture, it won’t freeze and expand and break your engine in the winter under extremely low temperatures. Coolant can last for up to three years or longer, depending on the kind of coolant you purchased: Inorganic Acid Technology (IAT), Organic Acid Technology (OAT) or Hybrid Organic Acid Technology (HOAT). It is crucial to change your antifreeze and check its consistency. Unchecked antifreeze can cause serious damage to your vehicle’s engine. Here are a few ways you can maintain your engine cooling system and know when to replace your coolant.

Ways to Maintain Your Engine Cooling System

12th Street Auto Care Center’s expert mechanics are happy to service your vehicle and all of its engine cooling system issues. We have special equipment that helps us to diagnose any problems with your cooling system, as well as to fix them. Financing is offered, so there is never any need to worry about being able to pay for our services. We are here to help you. We want to service you and your car. We recommend checking your coolant at least once a year to make sure it is still looking good and free of rust and sludge.

Signs My Engine Cooling System Needs Repair

There are a few ways you can tell when your engine cooling system needs to be repaired. Many of them can be seen, as they are caused by physical damage, or wear and tear, to the engine cooling system.

Engine Overheating

If you find yourself on the road and your engine’s temperature gauge on your dashboard rapidly shoots into the red zone or has slowly made its way over to the red zone, pull off onto the side of the road and call a mechanic and possibly a tow truck. It could mean that coolant somehow leaked out of your engine cooling system, or the coolant went bad and is no longer able to absorb the heat from the engine block.

Smoke from Underneath the Hood

Smoke coming from underneath the hood of your car is another potential sign that your engine is overheating. If you see smoke coming from your hood, pull over onto the side of the road and call for a mechanic and tow truck. If possible, poor water onto the engine or add coolant, but do not remove the radiator pressure cap. Very hot steam or liquid could shoot out of the pressure cap if removed and scald you.


Coolant leaking from your vehicle is a common sign that something is wrong with your engine cooling system. Rocks or debris from the road can cause harm to hoses or any other part and cause leaking. Sometimes, hoses can become old and warn out and spring a coolant leak. A good way to tell if your car is leaking coolant is to look under your car at the ground for any colored puddles or a trail of drops on the garage floor or driveway. Coolant, or antifreeze, can be orange, yellow, red, pink, green or blue in color.

Testing the Engine Cooling System for Leaks: if you are unsure about the state or condition of your engine cooling system, the auto mechanics at 12th Street Auto can take a look for you and diagnose any problems.

External Leaks

For external leaks, we can try the pressure test. Using a coolant pressure tester, we pump pressure into the engine cooling system to check for leaks. The pressure will force coolant or water out of the place that is leaking. Once the problem is addressed, we can take care of the rest, replacing hoses, clamps or any sort of rusty spot.

Internal Leaks

Internal leaks are much harder to see. White smoke coming out of your exhaust could be a sign that your vehicle is internally leaking coolant, which is burning up inside the combustion chamber. For internal leaks, we can use a combustion leak tester, or block tester, to check if coolant is leaking inside the cooling system. How this could happen is by an engine gasket going bad, because a gasket is meant to seal. If the seal is broken, coolant could escape and go someplace it is not meant to go.

Signs My Coolant Needs Replacing

After years of use, coolant, or antifreeze, can lose it potency and no longer work as well to cool your engine or prevent it from freezing. Depending on the kind of coolant you fill your engine cooling system with, it can last from three years to seven. Also, different coolants have different colors, such as blue, green, yellow, orange, red or pink.

There are a few ways to tell when your coolant needs to be replaced.

Color and Consistency

Coolant should be brightly colored as green, yellow, orange, red, pink or blue. It should be clear and not grimy or muddy in color or consistency. When checking your coolant, make sure your vehicle has been turned off for a good while beforehand. When your engine, radiator and coolant are cooled off, you can lift up the cap of the reservoir tank to look inside. You can also remove the radiator pressure cap and look inside there as well. If the back of the radiator pressure cap has brown sludge on it or brown gunk, it is possible that your antifreeze is bad. If you see floating chunks of rust or other sludge in either the radiator or the coolant reservoir, or reserve tank, it might be time to replace your coolant.

Coolant Hydrometer

The coolant hydrometer test can be used to check the condition of your coolant. By pumping some coolant into the hydrometer and shaking any air bubbles out, we can tell whether or not the coolant inside your engine cooling system is potent enough to keep your engine cool while running, and potent enough to stop it from freezing in the winter.

Multi-meter or Voltmeter

With a voltmeter, we are able to check if the coolant running through your engine cooling system is carrying an electronic current. Antifreeze that is carrying an electronic current is not good. The electronic current in antifreeze can cause damage to the interior of your engine and even mess with your car’s computer system. If the voltmeter gives us a reading higher than a desired number, the coolant should be replaced.

pH Test

By testing the pH of your coolant, we can tell if the coolant within your engine cooling system is too high or too low. The extreme levels are problematic, being either too basic or too acidic. pH testing strips work well. If your antifreeze is too basic or acidic, it should be replaced.

Replacing Old Coolant

If your coolant needs replacing, or you want to try some new coolant in your car, 12th Street Auto Care Center can clean your engine cooling system before filling it up with fresh coolant. We have a special machine that will give your coolant system a power flush. This will clear out any sludge, rust and grime that might have accumulated in your engine cooling system. It is also a good idea to flush everything out before refilling your system with new coolant, because antifreeze is not meant to mix. Also, mixing an old coolant with a new coolant will shorten the time of use for the new coolant, and might still cause damage to your engine cooling system. Once it is all cleaned out, it is ready to be refilled. 12th Street Auto recommends a coolant system power flush and refill, because it is the best way to clean out your engine cooling system and ensure its longevity.

Napa Service Assistant

You don’t have to be an expert to know that preventive maintenance is the best way to make sure your vehicle is running properly. Use our interactive vehicle tool to learn about the maintenance and services your NAPA AutoCare Center can provide.

Napa Interactive Maintenance Tool