Engine Coolant Over Temperature Ford: Simplified!

Are you tired of your car engine overheating? Does your coolant warning light keep coming on, making you worried about potential damage to your vehicle? “Engine coolant over temperature” alarm in the Ford vehicle can be a frustrating and worrisome issue for any driver.

When the engine gets too hot, it can cause serious damage to your car, leaving you with expensive repairs to deal with. But fear not, as there are solutions to this problem.

In this article, we will take a closer look at the causes of engine coolant over temperature and explore the different solutions available to prevent it.

So, why is engine coolant over temperature? The most possible causes of engine coolant over temperature include: malfunctioning thermostat, a coolant leak, a faulty water pump, a clogged radiator, or a malfunctioning engine coolant temperature sensor. One of the most common symptoms of engine coolant over temperature is a warning light on your dashboard. This warning light is designed to alert you when your engine is running too hot and needs to be cooled down. Other symptoms of engine coolant over temperature include steam coming from under the hood, a strange smell coming from your engine, or a loss of power while driving. If you suspect that your vehicle’s engine coolant is over temperature, it’s important to take action right away. Ignoring the issue can lead to costly engine repairs and even engine failure.

Bonus Read: Car won’t start after overheating

Causes of Engine Coolant Over Temperature Ford

Here are the causes of engine coolant over temperature alarm in Ford vehicle:

1. Stuck Thermostat

bad thermostat of engine

The thermostat is essentially a valve that regulates the flow of coolant through the engine. It’s located between the engine and the radiator and is usually mounted on the engine block or cylinder head, and enclosed in a housing. When the engine is cold, the thermostat remains closed, preventing the coolant from circulating around the radiator. 

When the thermostat is closed, the coolant keeps on circulating only around the engine. This allows the engine to warm up quickly.

Once the engine reaches its operating temperature, the thermostat opens up, allowing the coolant to flow through the radiator. This helps to maintain a consistent engine temperature and prevent overheating.

When the thermostat becomes stuck closed, coolant is unable to flow through the radiator to cool the engine. As a result, the coolant will not be able to exchange heat with the ambient air as it usually does when flowing through the radiator. This will cause the coolant to go over an optimum temperature.

illustration of how engine cooling system works

In the below animation, you can see how engine’s thermostat works:

Why does it happen?

One of the most common causes of a stuck thermostat is a buildup of rust and sediment in the cooling system. Over time, rust and sediment can accumulate in the radiator and thermostat, preventing proper valve operation. 

How to spot the issue?

To locate the thermostat, you just need to follow the upper hose of the radiator as its one end is connected to the thermostat. A thermostat is located closer to the water pump.

You can easily a thermostat is stuck in a closed position by touching the hose that connects the radiator to the thermostat. If the flow of water can’t be felt, then it indicates a need for thermostat replacement.

Another way to test a stuck thermostat is by removing it from the engine. You can test a stuck thermostat by boiling it in water in a pot and see if the spring of the thermostat moves. If it doesn’t, it means that the thermostat is stuck. You will have to replace it.

putting engine thermostat in boiling water to test it

2. Clogged Radiator

clogged radiator

When the engine is running, the coolant circulates through the engine block and absorbs heat. It then travels to the radiator, where it releases the heat into the surrounding air through a series of fins and tubes. The cooled coolant then returns to the engine block to repeat the cycle.

A radiator consists of a series of tubs and fins that help in maintaining the temperature of coolant circulating around the engine. The coolant flows through the radiator tubes while the radiator fan blows air over the radiator fins.

The hot coolant exchanges heat with the air and maintains its temperature.

How radiator becomes clogged?

A clogged radiator restricts the flow of coolant through the cooling system. This means that the coolant cannot effectively absorb and dissipate heat, causing the engine to overheat. If the radiator becomes clogged from inside, it can happen for several reasons, including:

  1. Build-up of debris: Over time, debris can accumulate in the radiator, blocking the flow of coolant. This can be anything from dirt and dust to leaves and other debris that gets stuck in the cooling fins. 
  2. Rust and corrosion: The cooling system is made up of metal components that can rust and corrode over time. This can cause flakes of rust to break off and clog the radiator. 
  3. Mineral deposits: In areas with hard water, mineral deposits can accumulate in the cooling system and clog the radiator. This can also happen if the coolant is not changed regularly, as the additives in the coolant can break down and form deposits. 

Furthermore, if radiator fins are clogged with ambient air dirt and dust i.e. radiator is clogged from the outside, it will disrupt the airflow. Furthermore, you should also visually inspect if the fins of the radiator are bent or not.

How to spot this?

To determine if a radiator is clogged, an effective method is to utilize an infrared thermometer to measure temperatures at various points. Inconsistent temperature readings may suggest that the radiator is obstructed and requires attention.

How to fix?

The best way to clean a clogged radiator is to perform a radiator flush procedure

To flush the cooling system, follow these steps:

  1. Drain the radiator: Begin by removing the valve at the bottom of the radiator to drain it completely.
  2. Fill with distilled water: Next, plug the radiator valve and fill the radiator with distilled water.
  3. Run the engine: Start the engine and drive for approximately 20 minutes, ensuring that the heater is running on high mode.
  4. Flush the system: After this, flush the water from the cooling system thoroughly.
  5. Add coolant/antifreeze: Finally, add the recommended coolant/antifreeze in a 50/50 ratio into the engine.

To clean the radiator from the outside, I would recommend using this cleaner. Use a soft-bristled paint brush and a jug of cleaning solution, and brush it on going in the same direction as the radiator fins. Make sure to make a cleaning solution in warm water. Keep radiator fins soaked in the cleaning solution for some time. Then, wash the radiator with a pressure washer.

3. Faulty Water Pump

A water pump is an essential component of a vehicle’s cooling system. Its primary function is to circulate coolant through the engine, radiator, and other cooling system components. The water pump is driven by a belt connected to the engine’s crankshaft. It has impellers that move the coolant through the engine and back to the radiator, where it is cooled before returning to the engine.

One way a faulty water pump can cause coolant over-temperature is by not circulating the coolant effectively. The impellers inside the pump may wear down or become damaged, reducing their ability to move the coolant through the system efficiently. This can cause hot spots in the engine, leading to overheating. 

In addition, the bearings that support the water pump’s shaft can wear out, which can cause the pump to leak or make noise. 

Furthermore, the water pump is sealed to prevent coolant leaks. However, over time, the seals can wear down or become damaged, leading to leaks. If the coolant is leaking from the water pump, it can lead to engine overheating and damage. If water pump seals are worn-out, the coolant will start leaking through weep holes.

Another reason why water pumps can fail is due to a too-tight belt. A belt that is too tight can cause additional stress on the water pump’s bearings and impeller, leading to premature failure. To prevent this issue, it’s important to ensure that the water pump belt is properly tensioned according to the manufacturer’s specifications.

How to fix?

If the impeller of the water pump is damaged, you have to replace the water pump. While installing a new water pump, make sure that you tighten the bolts properly.

Moreover, you should install a belt for the water pump with proper tension. If the belt is too tight, the excessive load will damage the water pump body.

If the bolt of the water pump is not properly tightened, it will cause vibrations which will result in bearing fracture.

4. Malfunctioning ECT or CHT Sensor

The ECT (Engine coolant temperature) and CHT (cylinder head temperature) sensors are responsible for measuring the temperature of the engine’s coolant and cylinder head, respectively. These sensors are essential for maintaining proper engine performance and preventing damage to the engine.

Ford vehicles have either ECT or CHT sensors. You need to check the factory manual to confirm. CHT sensor is usually located under the air intake manifold, on the cylinder head (passenger or driver side).

The difference between CHT and ECT sensors is that the ECT sensor is dipped in coolant and records the temperature of the engine’s coolant. On the other hand, the CHT sensor directly measures the engine’s temperature as it is attached to the engine’s head.

When the ECT or CHT sensors malfunction, they can send incorrect temperature readings to the engine control module (ECM), which can cause a variety of issues. 

The information gathered by these sensors is then sent to the engine control module (ECM), which uses it to determine the amount of fuel delivery and ignition timing needed to keep the engine running smoothly. 

If the ECT sensor malfunctions, it will send incorrect readings/signals to the ECU, which triggers “Coolant Over Temperature” message on the dashboard.

So, if your car isn’t overheating, but still you can see a message of engine coolant over temperature, you should check ECT or CHT sensor. In such cases, the ECU can throw a P1299 error code.

How to spot?

The first step is to check the pigtail and wires connected to the sensor. Look for any signs of burning, melting, or damage to the wires. Loose connections or corrosion can also cause issues, so ensure that the connections are tight and free from corrosion. 

If the pigtail and wires are in good condition, the next step is to check the sensor. Remove the sensor from the engine block and inspect it for any signs of damage. 

The CHT or ECT sensor can be tested by measuring its resistance. For the purpose of determining the resistance of the sensor at various engine temperatures, there is a chart available that lists the expected resistance value.

Here are the steps to test ECT sensor:

  1. Immerse the tip of the sensor in the water.
  2. Connect a digital ohmmeter to the two terminals of the sensor.
  3. Using a calibrated thermometer, compare the resistance of the sensor to the temperature of the water. Refer to the engine coolant sensor temperature vs. resistance
  4. Repeat the resistance at other temperatures by heating or cooling the water.
  5. If the sensor does not meet the specification shown in the temperature versus resistance chart, it must be replaced.

5. Coolant Leaks or Low Coolant Level

One of the most common causes of the “Engine Coolant Over Temperature” message is a coolant leak.  The coolant system is designed to operate at a specific level, and if the level drops below that point, the engine can overheat.

There are several areas of the coolant system that can develop leaks, including the radiator, hoses, water pump, and thermostat housing. Over time, these components can become worn or damaged, leading to leaks. 

Another cause of coolant leaks is a blown head gasket. The head gasket sits between the engine block and cylinder head, sealing the combustion chamber and coolant passages. If the head gasket fails, coolant can leak into the combustion chamber, resulting in a loss of power and overheating. 

Low coolant level can also cause the water pump to fail. When the coolant level is low, the pump may not be able to circulate the coolant efficiently, leading to overheating of the pump. In addition, low coolant level can cause air bubbles to form in the system, which can cause hot spots and lead to overheating.

How to spot?

You can check the following areas of coolant leaking from the following components:

  1. Overflow tank
  2. Radiator hoses
  3. Heater core hose
  4. Thermostat
  5. ECT sensor
  6. Water pump
  7. Head gasket

If coolant is leaking through the head gasket, you can’t spot it as it will burn in the engine. The signs are that your engine will produce white smoke from the exhaust. Furthermore, if you open oil filler and radiator cap, you will observe a brownish texture. This indicates that coolant and oil mix when a head gasket blows out.

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