Problems with a vehicle's cooling system can be difficult to diagnose. If the vehicle's engine is running too hot, overheating, or too cold, there may be a leak in the system or one of the system components is malfunctioning. You need to pay attention to the symptoms that appear on the vehicle and check the cooling system itself to be able to find the source of the problem in the vehicle.
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Method 1 of 3: Determining the Presence of Interference
Step 1. Pay attention to the temperature meter
Early signs of a problem with the vehicle's cooling system can often be seen through a temperature meter. If the vehicle's temperature continues to rise consistently, or has recently started experiencing overheating issues, there may be a problem with the vehicle's cooling system.
- The vehicle temperature meter should indicate a tolerable temperature range. Even if the vehicle's engine is not overheating, if the temperature is above the tolerable temperature range, there may be a problem with the vehicle.
- If the temperature meter shows red when the vehicle is running, it means the engine is overheating. Immediately pull over and turn off your vehicle.
- Faults in the cooling system can also cause the engine to overcool. In this case, the temperature meter remains in blue.
Step 2. Check engine light
The engine light on the dashboard can indicate a problem with the car's cooling system. Your vehicle's engine check light comes on when one of the car's sensors sends a signal to the ECU (Electronic Control Unit) informing you that there is a fault. If any part of the vehicle is not functioning properly, the ECU will notify it via the engine check light.
- The error code that causes the engine light to turn on uses a code that can be read by the OBDII scanner.
- Many vehicles have dashboard lights that alert the driver when the engine is experiencing a lack of coolant or temperature extremes.
Step 3. Identify the coolant under the car
Leaks are a common problem in cooling systems. If you see a puddle of liquid under the vehicle, this may be due to a coolant leak. Touch the stagnant liquid with your finger, then wipe it on the white paper. The oil is usually black or brown, while the water from the air conditioner is clear, and the coolant is green, pink, or orange.
Leaks can cause the cooling system to malfunction and fail to maintain an appropriate engine temperature
Step 4. Check the coolant level in the vehicle
If you feel a coolant leak in the vehicle, open the hood when the engine is cold and look at the coolant reservoir. This reservoir has marking lines that indicate the minimum and maximum level of vehicle coolant. Record the coolant level in the reservoir, and check again a few days later. If the level drops, the coolant may leak or catch fire.
- Make sure to check the coolant reservoir every time the engine is at the same temperature.
- If you can't find the coolant reservoir, consult your vehicle's user manual.
Method 2 of 3: Visually Checking the Cooling System
Step 1. Let the engine cool down
The engine case will be so hot when the engine is running that you could burn yourself if you touch it before it cools down. Let the engine sit for a few hours before opening the hood and looking for coolant leaks.
- If the hood is still warm, the engine underneath is still hot.
- If the vehicle is overheating, you will need to wait longer before it is safe to touch.
Step 2. Wear the right gear
Before starting this project, wear all necessary safety equipment. Eye protection should be worn as you will be dealing with a coolant leak. You may not wear gloves, but they should be worn because they can protect your hands from scratches and pinches while working.
- Eye protection is mandatory when dealing with leaks to protect you from liquid dripping or spraying under pressure.
- You can use safety glasses or goggles to protect your eyes.
Step 3. Check for damage to the radiator cover
Usually cooling system problems can be caused by damage to the radiator cover. When functioning properly, the radiator cap can release excess pressure that has accumulated in the cooling system. However, over time the cover can wear out or get stuck. If the radiator cover looks rusty, corroded, or is covered with grease, this is likely the cause of the cooling system problem. You can replace the radiator cover by twisting it off and installing a new cover.
- The price of a radiator cover is usually quite affordable and can be purchased at an automotive repair shop or shop.
- Never remove the radiator cover while it is still hot. The hot liquid inside can gush out and burn you.
Step 4. Pay attention to the water pump, if possible
The water pump in the vehicle pumps a mixture of water and coolant through the engine and into the radiator where the airflow helps remove heat. Look for visible signs of leaks or water pump failure in the engine compartment. The water pump is belt driven so check for damage to the belt which usually means the water pump pulley has stopped moving and is rubbing against the belt.
- If the water pump doesn't work properly, the engine can't get rid of the heat it generates, so it overheats.
- A damaged water pump drive belt must be replaced after inserting a new water pump.
- If you do not know where the water pump is in your vehicle, consult the user manual or the vehicle manufacturer's website.
Step 5. Assess for damage to the coolant hose
Look for the hose that runs from the radiator to the engine, then follow it as far as possible. If any hose is bent, the cooling system will not function properly. Cracks also indicate a leak, but even if it hasn't already leaked, a cracked hose should be replaced. Watch for damage to the hose or signs of friction from kinked hose or accessory belts.
- If one of the belts has rubbed against the cooling hose, both need to be replaced. Make sure that the belt and the new hose are far enough apart so that they no longer rub against each other.
- Coolant leaks can cause pooling under the vehicle and overheating of the engine.
- Replace leaky or damaged radiator hoses.
Method 3 of 3: Testing Common Faults in the Cooling System
Step 1. Determine how long the coolant has been in the system
If there are no signs of a coolant leak but the vehicle still can't keep its temperature within the tolerable range, chances are that the coolant is no longer good. Most vehicle manufacturers recommend pouring coolant every 50-100 thousand km. If the distance is further than that, this is likely the cause of the disturbance in the cooling system. Drain and pour the coolant by opening the petcock valve at the bottom of the radiator and draining it into the container, then fill the cooling system with water and restart the engine for a few minutes. Repeat this process a few times to remove all the old coolant, then fill it with a balanced ratio of water and coolant mixture (1:1).
- Most coolants are pre-mixed with water, but you can buy just coolant and mix it yourself with water.
- Coolant can be purchased at repair shops, gas stations, and major retail stores.
Step 2. Look for signs of head gasket damage
If you see coolant leaking from the engine under the exhaust manifold and white smoke coming out of the exhaust, your vehicle's head gasket may have exploded. Exploding head gaskets will cause coolant leaks, engine overheating, drastic power shortages, and exhaust discoloration.
- Repair of a blown head gasket is carried out by removing the tube head from the engine so it is best to use the services of a professional.
- If you believe the vehicle's head gasket has exploded, stop driving immediately.
Step 3. Determine if the thermostat is working properly
The vehicle's thermostat determines the operating temperature of the engine. If the thermostat does not work in the open position, coolant will continue to flow through the radiator and the engine will become too cold. If it is damaged in the closed state, the coolant will not be able to reach the radiator, resulting in overheating. Look for signs of leakage or oxidation around the thermostat to determine the cause of the problem.
- If it rusts, chances are the thermostat isn't working properly.
- A leak in the area around the thermostat causes it to malfunction.
Step 4. Use the OBDII scanner to obtain the machine error code
If the vehicle's check engine light comes on, install an OBDII scanner to identify the problem. Connect the OBDII scanner cable in the port under the dashboard (on the driver side), then turn the key to “accessories” and turn on the scanner. Depending on the type, the scanner will provide an error code or description of the error that occurred in English.
- Many repair shops use OBDII scanners to check codes on cars for free.
- If the scanner only gives an error code, check the vehicle manufacturer's website for a description of the error.
Step 5. Look for coolant leaks
If the vehicle's cooling system leaks, the engine cannot be properly cooled and may overheat. When visually inspecting the cooling system, be sure to look for signs of coolant spray or leaks from the radiator, hoses, and pump. Follow any visible coolant in the engine compartment to its highest point to determine the source of the leak.
- It's a good idea to spray the engine with a hose to clean any used coolant, then restart the engine to locate the new coolant leak.
- If the leak is in the radiator, this part needs to be repaired or replaced by a professional.
Step 6. Use a pressure tester to find hard-to-find leak points
Another way to find out if there is a problem with your vehicle's coolant system is to use a pressure tester. Remove the radiator cover from the engine and screw the pressure tester into place. Turn on the vehicle heater without starting the engine so the cooling system can build up pressure. Look at the gauge on the pressure tester for a sudden drop in pressure, indicating a leak. Then, listen for a blast of air in the cooling system to locate the leak.
- Pressure testers can be purchased at a repair shop.
- The coolant system will need to be drained in order for the pressure tester to work properly.
