Radiator leaks can reduce the amount of coolant and cause the vehicle to overheat, although there are other clues that indicate a similar event. If you notice any signs of a radiator leak, you can fix it before it becomes a problem. There are several ways to seal cracks and small holes in the radiator so you can get back to driving without any problems. There are also a few tricks you can use in an emergency situation to seal small leaks long enough so you can take your vehicle to your home or repair shop.
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Part 1 of 3: Identifying Radiator Leaks
Step 1. Watch the rise in the temperature meter
The radiator dissipates heat to maintain the optimum operating temperature of the vehicle's engine. A leak in the radiator causes coolant to drop, which reduces the system's ability to cool down. Before the cooling system starts to fail, the temperature meter on the dashboard will go up. If the vehicle continues to be consistently warm, or begins to experience overheating problems, the radiator may be leaking.
- Do not forget that excessive temperature will cause serious damage to the vehicle engine. Stop driving if the vehicle starts to overheat.
- If the vehicle temperature is hotter than normal, there may be a slight leak because there is still enough coolant in the system to keep the engine cool enough to operate.
Step 2. Watch for puddles under the vehicle
An easy way to identify a coolant leak is to look for puddles under the vehicle. Of course, there are some fluids in the vehicle that may be leaking so you need to identify them by looking closely and even touching them. Remember, if you turn on the air conditioner while driving, the moisture from the A/C compressor will drip and the vehicle may also have an oil leak instead of coolant. If you see puddles under your vehicle or where your vehicle is usually parked, look carefully.
- Coolant having a green or orange color looks different than motor oil or water.
- New motor oil can be yellowish in color, but if it has been in the engine for a long time it will appear dark brown or even black.
- The dew drops from the air conditioner are usually just water.
Step 3. Check the coolant reservoir
If you suspect that the radiator has an unidentified leak, check the coolant level in the reservoir. Most coolant reservoirs already have clearly defined minimum and maximum level markings. Draw a line for the current liquid level on the reservoir using a marker or take a photo with your phone so you can remember it on the first check. Open the hood and check again after a few hours of driving to see if the altitude has decreased. If the engine is cold during the initial inspection, wait for the engine to cool before checking again.
- The coolant must remain in the sealed system and not change its height.
- If the coolant level decreases on the second check, it means there is a leak somewhere.
Step 4. Look carefully at the engine case
If you notice rust and discoloration of the parts surrounding the radiator or on the radiator itself, there may be a coolant leak in that area. Since a leak causes coolant and water to escape from the radiator when the car is driven, the parts that come into contact with the liquid will rust over time. While all engine components will eventually rust, if you notice an area with an abnormal amount of rust around the radiator, there may be a leak.
- Look for signs of coolant around the identified rust spots.
- You can find a leak by following the coolant trail in this rust to its highest point.
Part 2 of 3: Looking for Leaks
Step 1. Let the engine cool down
The radiator has an important task to maintain the operating temperature of the engine. As a result, the radiator and associated hoses can become very hot. Despite the heat, the cooling system is under high pressure. If you remove the radiator cap, hot coolant and steam can erupt, endangering yourself. Park the car in front or in the garage where you will be working and let it cool for a few hours before starting the project.
- Open the hood of the car after parking so the heat can spread freely.
- Be prepared to wait a few hours for the engine to cool down enough before working.
Step 2. Wear appropriate protective equipment
Since the cooling system is under high pressure, it is important to wear safety glasses when working on radiators. Although the engine must be cold so that it is safe to touch before working, the cooling system is under high pressure so it can spit gas when the radiator cap is opened. You'll also get under your car as you work, so safety glasses will protect your eyes from falling debris.
- Always wear safety glasses when working under a vehicle.
- You may also want to choose gloves to protect your hands from pinching and residual heat.
Step 3. Wash the radiator with a hose
Leaks will be easier to find if the radiator is clean. Use a hose to rinse the radiator and surrounding components so you can pinpoint the location of any new coolant leaks that appear in the engine compartment after starting the car. When washing the radiator, look for signs of cracks in the radiator itself or on both ends of the tank.
- It is important to use soap when cleaning the radiator.
- Use a kitchen paper towel to wipe the area with excess oil.
Step 4. Start the car and look for any new leaks
One of two methods for identifying the location of a radiator leak is to start the car when the engine is clean. When the engine is running, look closely at the radiator and its surroundings for signs of a leak, you may see steam or jets of liquid escaping from the leak point, liquid dripping from the radiator or its ducts, or hear a hiss that cannot be seen from your standing position. This method can guide you in the right direction, but the engine will need to be turned off again to see the more difficult-to-see parts of the radiator.
- Look for jets of liquid or gas from radiator cracks.
- Look for coolant seepage flowing down from the leak point above it.
- Listen for hissing from the area around the radiator for any invisible leaks.
Step 5. Use a pressure tester to find leaks
You can find this tool in a repair shop. To use it, make sure the engine is cold and remove the radiator cap or pressure from the cooling system. Install the tester in place of the radiator cap using the supplied adapter. Once the tester is securely in place and the system is resealed, use the tester to pump 10 pounds (4.5 kg equivalent) of pressure into the cooling system. When the meter shows an indication of pressure loss, it means that there is a pressure leak in the system. Follow the hissing air from the crack to find it.
- Be careful not to add pressure more than 10-15 psi. Otherwise, you could damage the radiator and add to the leak. The cooling system operating pressure should be listed on the radiator cap and you should not exceed this number when testing pressure.
- Look for leaks in the coolant and radiator lines as they can crack over time.
Part 3 of 3: Repairing Radiator Leaks
Step 1. Use a commercial sealant
There are several products on the market that are designed to seal leaks in radiators easily and simply. Although the brands vary, the way to use this product is generally the same. Start by making sure the engine is off and cold. Remove the radiator cap and pour the sealant directly into it. Next, add the coolant and water mixture if there is little left in the radiator. Replace the radiator cap and start the engine. The leak will be sealed as the sealant flows through the cooling system.
- This solution is not permanent as the radiator will still require epoxy and professional handling, but it is sufficient to seal minor leaks until a permanent repair can be made.
- Leave the engine running for 5-10 minutes while the sealing product flows through the cooling system.
- After starting, leave the engine off overnight to allow the sealant to harden.
Step 2. Use an epoxy to seal any visible cracks
When you notice any cracks, clean the area thoroughly. Any residual oil or dirt in the area can prevent the epoxy from sealing the radiator. Use brake cleaner and a rag to remove stubborn grease. Once the area is clean, allow it to dry completely before applying the epoxy. Massage the epoxy into your hands until it's tough enough to spread over the cracks. Work thoroughly and keep the epoxy at least 0.3 cm thick so that it can withstand the pressure of the cooling system when the vehicle is running.
- You can buy an epoxy radiator at most repair shops.
- Leave the epoxy overnight before starting the vehicle.
Step 3. Use an egg to seal the leaky radiator
The egg isn't a permanent solution, but it can seal a pinhole-wide leak in the radiator until it can be repaired by a professional. First of all, separate the egg whites and yolks. Discard the egg whites, then put the yolks from 3-4 eggs into the cooling system through the radiator opening. Start the engine like using a sealant product and let the egg yolks drain through the cooling system. The yolk will freeze and seal any small radiator leaks and allow it to hold pressure long enough for the car to be taken to a repair shop or garage.
- Egg yolks can potentially clog the cooling ducts and are not recommended except in an emergency.
- This method is less reliable than commercial products for repairing radiators permanently.
Step 4. Use pepper to seal any small leaks
In an emergency, peppercorns can also be used to slow down and stop leaks in the radiator long enough for the car to be taken to a repair shop or garage. Wait for the engine to cool completely, then open the radiator cap and pour in about half a bottle of black pepper. Like sealant or egg yolk, it will flow through the cooling system and stick to the cracks as the pressure tries to push the peppercorns out. This creates a temporary seal that can be used to hold the coolant and pressure long enough for short rides.
- As with egg yolks, this method is not recommended except in an emergency and is not as reliable as commercial products.
- Pepper can also seal longer cracks than egg yolks, but is only recommended for small leaks.
Step 5. Check the repairs made
Regardless of the method used to seal the radiator damage, it is important to check the results after the seal has been allowed to harden. After driving for a while, look for signs of a leak. If you think the coolant is still leaking, perform a similar test to find the source of the leak. There may be more than one leak or the repair is not sufficient enough to shut down the system. Identify new leaks and repeat the process
- Egg yolks and peppercorns are not meant to be a permanent solution to coolant leaks. Consider using a sealant or epoxy to ensure a repair once you get home.
- Large cracks may not be repairable and it looks like the radiator needs to be replaced.
- Be sure to refill the cooling system with a balanced mixture of coolant and water (50/50) when the level is low enough.
