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Leaking radiator – how to fix it? What to do if the coolant is low?
Leaking radiator – how to fix it? What to do if the coolant is low?
The radiator is a heat exchanger in a car that cools the vehicle's engine. Have you noticed steam coming out from under the hood? Does the light on the dashboard indicate a decreasing coolant level? Is the temperature in the cooling system rising alarmingly? This may mean that the radiator is leaking liquid. Unfortunately, it sometimes happens that such an unpleasant surprise awaits us while traveling, a few hours' drive from home. How to save yourself and seal the radiator? Radiator sealant may help.
From the article you will learn:
- What causes coolant leakage?
- How to diagnose a coolant leak?
- How to seal a radiator step by step?
- Is it necessary to replace the radiator?
What causes coolant leakage?
When you notice a leak in the cooling system, immediate action should be taken to prevent serious engine failure and a cracked head. In such a case, the most important thing is to diagnose the coolant leak, find its cause and the place from which the fluid is leaking.
The most common cause of coolant leaks is a leak in the radiator due to mechanical damage, corrosion or wear of the seals. This element has reduced resistance to corrosion and all types of damage. In particular, it is worth paying attention to older cars, where the connections between the cooling system lines are often leaking. Sometimes, however, the problem concerns the gasket under the engine head, which can also be damaged, which in turn increases the risk of leaks from the expansion tank.
If the cooling system leak is due to a worn component, it should be repaired or replaced. Such faults most often occur in older car models. Although the problem can occur in newer vehicles just as well.
What else could cause a leak in the cooling system?
The radiator's job is to release heat to maintain the engine's temperature. The coolant circulating in the cooling system takes the heat from the engine and transfers it to the radiator, where it is dissipated by the air flow, preventing the engine from overheating. For this reason, it is installed in the place where it will do its job best, i.e. at the front of the vehicle.
Even though the coolant reservoir is protected by grilles in the hood or bumper, the radiator is exposed to various mechanical damages, e.g. impacts from stones, branches or other road obstacles. Even a small collision can affect the operation of the cooling system.
The cause of coolant loss may also be improper use. The radiator is a delicate element that can be damaged by engine overheating, too high pressure in the cooling system or using the wrong coolant. It is also a big mistake to ignore engine overheating warnings and rarely check the coolant level, as this can damage the radiator and other cooling system components, which in turn results in leaks and more serious engine failures.
Another mistake is to top up the coolant with plain water instead of distilled water. This can start a corrosive process that is hard to stop. Scale also precipitates from the water, which eventually settles on the walls of the cooling system, causing channels to become clogged and reducing cooling efficiency.
Coolant freezing
Adding regular cold water is particularly harmful because it can simply freeze, which will lead to leaks and permanent damage to the radiator. Coolant has a lower freezing point and anti-corrosion properties. Winter coolant also provides excellent protection against freezing.
Boiling the coolant
In turn, low coolant level, water pump failure or thermostat damage can cause a sudden increase in coolant temperature. When the coolant temperature exceeds a safe level, it boils, which leads to the generation of water vapor in the cooling system. As a result, the pressure in the system increases, which can damage hoses, seals or the radiator itself, and also lead to serious engine failures.
Consequences of driving with a low coolant level
The coolant in the cooling system has many important functions, such as removing heat from the engine, preventing overheating and protecting against corrosion. Regularly checking and topping up the coolant is essential to maintaining the correct engine temperature. Driving with a low coolant level can lead to serious consequences, such as engine overheating, which in turn can cause head gasket failure, a cracked head or even complete engine seizure. A sudden coolant leak can also contribute to:
- water pump damage,
- too high pressure in the cooling system,
- the formation of rust and deposits in the entire system,
- reducing the efficiency of the vehicle interior heating,
- increased fuel consumption.
Coolant Leak Symptoms
Why should you take specific actions to eliminate the problem as soon as possible? A leaking radiator negatively affects driving safety and comfort. If you regularly top up the fluid, you have more time to repair it. Let's think about whether you always remember this. If we ignore the lack of coolant, we can expect that after some time the engine will stop working properly.
It is worth mentioning that leaks at lower temperatures, in winter and autumn, are not as dangerous as when using the vehicle in the summer, when temperatures are significantly higher. Then there is an increased risk of the drive unit overheating.
How do you know if your coolant is leaking? The first symptom may be a noticeable drop in coolant level, which should be checked regularly. Another important sign is the appearance of spots or a puddle of coolant under the car, especially after parking the vehicle. It is also worth paying attention to sudden engine overheating, an increase in the temperature indicated by the gauge, and coolant leaking under the expansion tank cap.
Radiator leaks – how to diagnose coolant loss?
Diagnosing a coolant leak is not easy, especially when it is initially small. To check what type of liquid is leaking from the car, it is best to park it on a smooth surface, it can be concrete or asphalt. When a stain appears, soak a tissue in the liquid. If it is coolant leaking, the soaked tissue will be burgundy, blue, yellow, green or purple. Its smell is significantly different from oil, which is why many people claim that it is difficult to confuse it with any other.
A warning light on the dashboard will alert you to a coolant leak , at least in most cars. However, it's possible for air to enter and fill the reservoir, and in this case, the warning light won't alert you to a radiator leak.
Also, just visual inspection of the radiator can indicate whether the poor condition of the radiator is responsible for the loss of coolant. There may be visible traces of leaks on the component. They should be a different color from the rest of the radiator. There may also be limescale dust on the radiator.
Remember that only high temperatures, a hot engine, and increased coolant pressure will cause coolant to leak through a leaky radiator. The sooner you respond to irregularities, the more effectively you can prevent the leak from getting worse. The radiator should be sealed immediately after the problem is noticed.
How to locate a leak?
To ensure that the cooling system is functioning properly, the coolant should be checked regularly and topped up if necessary. However, it may happen that, despite topping up, the coolant level is still insufficient. In this case, you should immediately find the coolant leak to avoid more serious engine damage. First, check the radiator cap, radiator area, hoses and cooling system connections for visible traces of fluid or damp spots.
The next step is to check the head gasket and the fluid content in the expansion tank, because damage to these elements can also cause leaks. In some cases, it may be necessary to use a special UV dye, which will help locate leaks in hard-to-reach places. You can buy a special coolant with dye in automotive stores or garages specializing in cooling system diagnostics. After adding the dye to the cooling system and illuminating the engine with a UV lamp, the leak will become visible thanks to the characteristic glow.
If self-diagnosis does not bring results, it is worth consulting a mechanic who will perform a detailed inspection of the cooling system.
How to Fix a Leak? Effective Radiator Sealing Methods
It's much more difficult to troubleshoot a problem if you don't know exactly where the fluid is leaking from. Causes could include a worn coolant pump, a cracked cylinder head connector, corrosion on metal pipes, damaged rubber hoses, or a rusty hose clamp. If you caught the leak relatively early and it's not severe enough to require a radiator replacement, a radiator sealant can help repair the leak. It seals smaller leaks as well as hairline cracks.
If the leak is larger or affects key cooling system components such as the radiator, hoses or water pump, they may need to be replaced. In some cases, it is possible to solder or weld a damaged aluminum radiator, but this requires experience and the right tools. However, if the cause is a damaged head gasket, the only effective solution is to replace it, which requires dismantling parts of the engine.
Too much coolant in the expansion tank – how to deal with it?
Too much coolant in the reservoir can lead to cooling system failures, such as excessive pressure, leaks or even damage to the seals. If you notice that there is too much coolant, it is best to remove the excess as soon as possible. This can be done using a syringe with a hose or a drain hose, carefully drawing off the excess fluid to the level recommended by the manufacturer. It is also worth checking whether the overfill is not caused by a cooling system fault, such as a faulty reservoir cap that may not be releasing excess pressure. If the problem of too high a fluid level occurs regularly, consult a mechanic to rule out more serious faults, such as contamination in the coolant and exhaust gases entering the cooling system, which may indicate a damaged head gasket.
What to do if you have a leaking radiator cap?
A leaking radiator cap can cause a drop in pressure in the cooling system, which negatively affects its efficiency. If you notice coolant leaks around the cap or suspect that it is not maintaining the proper pressure, it is worth taking action as soon as possible. To do this, check the condition of the cap gasket - if it is cracked, worn or deformed, it will need to be replaced. Similarly, if the cap itself is damaged or loose, then it is also recommended to replace this element.
Quick leak repair
It's always a good idea to have a radiator sealant in your car , so you can use it even when you're traveling and notice a damaged component causing a coolant leak. Radiator sealants are available in a wide range of products.
Radiator sealant My Car
Moje Auto offers a radiator sealant that eliminates cracks up to 0,9 mm. It can be used on all radiators, both metal and aluminum. It is completely safe, does not clog the radiator, and is universal – suitable for all types of mechanically powered vehicles.
The second option is a radiator sealant powder , which can seal your radiator in 20 minutes. Similar to the radiator sealant, it can be used in all types of cooling systems. Radiator sealant powder does not affect the system's performance and effectively protects it from recurring leaks.
Sealing the radiator step by step
A large coolant leak can cause a serious cooling system failure. When the first symptoms of a coolant leak appear, do not wait, but start repairing immediately. Check how to seal the radiator step by step using powder or radiator sealant Moje Auto!
Step
To seal the radiator using the appropriate agent, unscrew the fluid filler cap and first fill the coolant level to the minimum required level. Remember to pour the agent into the expansion tank and not directly into the radiator.
Step
Coolant losses in the cooling system are best supplemented with a preparation with the same properties as the one currently used. Pay attention to whether the fluids are based on the same type of glycol, and also whether they are intended for radiators made of a specific material (e.g. aluminum) and whether they have a similar freezing point.
You also need to be careful when using concentrate. As the name suggests, this coolant must be diluted first.
Step
Once the coolant has been refilled, warm the coolant by running the engine, but monitor the temperature to prevent overheating. If using a liquid sealant, pour it into the radiator, or if using a powdered radiator sealant, pour it into the cooling system through the filler hole. The radiator sealant must be distributed throughout the system, so leave the engine running for several minutes.
Remember that if the leak is larger, which indicates another leak from the radiator, repair will be necessary in the workshop.
Moje Auto radiator sealing powder
Coolant Leak Repair Cost
The cost of repairing a coolant leak depends on the cause of the fault. Sealants cost around PLN 30–100, and replacing hoses or clamps is around PLN 50–200. More serious repairs, such as replacing the radiator (PLN 300–1500), water pump (PLN 400–1000) or head gasket (PLN 2000–5000), are associated with higher costs. The final price of repairing a coolant leak depends on the scope of work and rates applicable in a given workshop.
Cooling System Failure – When Is Replacement Necessary?
A large coolant leak may indicate that the radiator is already worn out enough. In such a case, the only reasonable solution is to replace it. However, this is not an easy task and you must be prepared to break your household budget. In most cars, it is necessary to dismantle the front bumper and headlights.
In addition, the process also involves removing the fluid from the cooling system, disconnecting the fan, and dismantling the lines. Are you confident that you can handle this task yourself? You must remember that after replacing the radiator, you need to bleed the system and refill it with new coolant. In this case, it is definitely worth considering calling a mechanic.
Sealing the radiator – summary
- The most common cause of a leaking radiator is its leakage due to long-term use and natural wear of the cooling system components. The problem therefore particularly affects older car models.
- A long-term radiator leak reduces coolant pressure and can result in the engine overheating.
- To diagnose a cooling system leak, place the car on a smooth surface and soak a tissue in the leaking fluid. If it is coolant, it will turn blue, burgundy, yellow, purple or green.
- We can seal the radiator with a special radiator sealant or radiator sealing powder.
- If the leakage is exceptionally large and the radiator is worn out, it is recommended to replace it.
FAQ
How to find a coolant leak?
To do this, thoroughly check the radiator, lines, connections and expansion tank for any damp spots of coolant. In hard-to-reach places, it may be helpful to use a UV dye, which will reveal the leak under a UV lamp. If the cooling system leak is not visible, it is worth consulting an experienced specialist.
How to temporarily refill coolant?
When coolant leaks, the first step is to top it up to prevent cooling system failure. The next step is to use a good quality cooling system sealant, which can temporarily seal minor leaks and slow down further leakage.
Leaking radiator – when is replacement necessary?
If the radiator has numerous corrosion points, mechanical damage or cracks, repair may be ineffective and it is better to opt for a new part. Delaying the replacement may lead to engine overheating and expensive repairs.
