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Radiator Sealant: Everything You Need to Know!

Radiator Sealants

A radiator sealant is one of the most cost-effective and the fastest methods to repair a leaking radiator. However, it should only be a temporary fix and should only be used if the leak or the damage of the radiator is not severe. There are different types of radiator sealants that you can use to stop a radiator leak – the liquid, powder, and tablet sealants. Radiator sealants do not require any form of preparation. You just need to add it directly into the vehicle’s cooling system. It is a chemical that will form a coating over the small holes or pinholes when applied. The coating over the pinholes is what stops the leaking, letting your vehicle run until you get to a repair shop to have it fixed properly. 

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However, there are some radiator sealants that can offer permanent solutions to the leak problems but it can only last for months. There are also some leaks that cannot be fixed using radiator sealants. How can you determine if your radiator leak can be fixed by a radiator sealant? Is fixing it with a sealant enough?

Radiant Sealant: Is radiator sealant bad?

A car’s radiator is exposed to a lot of heat while the engine is running. It is the one that helps dissipate the heat which the engine is generating. It cools down the coolant or the antifreeze that circulates through the engine, enabling it to operate at exceedingly high revolutions. 

With the radiator that plays an important role in the car’s cooling system, it is important that it is always in a good, working condition. It helps in keeping the engine from overheating. When the engine overheats, many components of the car can become damaged like the engine, thermostat, gaskets, and other cooling system components. The radiator itself can also fail when this happens. 

If you notice that your radiator is damaged or is leaking, it is important that you fix it immediately. One of the easiest and quickest ways to fix a radiator leak is by using radiator sealants.


Radiator sealants or stop leak is a known additive that is made and designed to help seal the radiator’s minor leaks and the in-between components’ leaks. There are several types of radiator sealants and each one works a bit differently than the other but the end result is somewhat alike. It usually has ceramic fibers, filler particles, and sodium silicate that tries to seal the pinhole leak by hardening and solidifying it. 

A radiator sealant is a good way to stop a radiator leak but it is important that you know what kind of sealant you choose. 

  • Radiator sealant with particle fillers.

Sealants with fillers such as metallic, ceramic, or organic will flow through the radiator when used and will be forced into the radiator piping gap when the system is under pressure, making the particles bind and making a temporary seal. However, when you flush out your coolant or when you fill it up, it could flush out some of the filler, enough to remove the seal and create a new leak. 

  • Radiator sealant with ceramic fibers. 

Ceramic fibers found in some radiator sealant utilizes the micro-sphere nano-technology to produce a patch in the radiator that is more secure and fibrous. The ceramic fibers will cure and will make a semi-permanent seal when heated. These fibers can hold out against the flushing of your coolant without tearing the seal better than the particle fillers. 

  • Radiator sealant with sodium silicate. 

The sodium silicate or the liquid glass as it's commonly known, can be melted at around 100 to 105 degrees Celsius or 212 to 221 degrees Fahrenheit. This liquid can reach into a leak located in the engine’s hot portion as it circulates in the cooling system. When it reaches the needed temperature, it will begin to melt and form a hard seal. The liquid glass will need a temperature of up to 810 degrees Celsius or 1,490 degrees Fahrenheit to be able to melt again. It means that it can form a very strong seal that can withstand an extreme amount of heat. 

It is important that you know the different types of radiator sealants and when you can use them effectively since not all radiator leaks can be fixed with a sealant. Choosing a right radiator for your car’s radiator leak is not easy. It will require a lot of research since there are a lot of sealants available in the market today. You would want to get something that works best and won’t cause any more damage to your car. 

Since radiator sealants work best in fixing radiator holes before they become bigger and severe, one thing you need to consider is how long you have had the leak and it’s size. If the leak has been there for a while, fixing it with a radiator sealer might not suffice. It might need a more permanent fix and have it repaired by a mechanic. 

Next thing you want to consider is if the sealant can prevent clogging since clogging can become a side effect when you are using one. It usually clogs around the heater core. If you pick a sealant, check its ratings, reviews, or if it has a good reputation for fixing leaks and flowing through the engine without jeopardizing the overall engine operation.  

You also need to consider the formulas used in the radiator sealant. The formulas or compounds used in each sealant can affect the engine differently. You need to research which one works best. It has been said that the liquid aluminum and extreme cool are some of the best ones since they are well-known to be generally safe. 

 

Radiator Sealant: What is the best radiator sealant?

There are so many radiator sealants or stop leaks being sold in the market today. How will you know which is the best one? Here is our list of the best radiator sealants in 2021. 

  • K-Seal ST5501 Permanent Coolant Leak Repair.

This radiator sealant can help fix issues like a radiator leak, head gasket leak, engine block leak, or water pump leak. To use this sealant, all you have to do is add it directly into the coolant system. It helps create a fast solution that is long-lasting. 

With the help of this radiator sealant, the holes or cracks will be sealed up and your engine will continue to function as normal. It is made with high-quality microfibers that bond together to form a seal, coating the holes and cracks. 

  • Bar’s Leaks Liquid Aluminum Stop Leak.

This is considered one of the best radiator sealants in the market today. It is known to be very effective in sealing leaks. Aside from fixing radiator leaks, it can also fix heater core leaks, freeze plug leaks, and gasket leaks. Its ingredients include liquid aluminum and extreme cool. 

These two sealant materials, like mentioned earlier, are known to be effective in sealing leaks and generally safe to use. This radiator sealant not only seals the leaks but it also makes sure that the problem or the same leak will not occur again. 

Using this kind of sealant does not require you to flush your coolant or antifreeze out from your system. You just need to add it directly into the cooling system. It will only take around twenty minutes to seal the leaks up. It is also versatile since it can work with different coolants such as red, blue, pink, yellow, orange and green non silicate and silicate-based antifreeze. 

  • Bar’s Leaks HDC Radiator Stop Leak Tablet.

This radiator sealant is in tablet form and is also known as one of the most effective sealants. It also offers a great value for your  money. It not only seals the radiator leaks but it also helps control electrolysis. This sealant is good for preventing rust or corrosion, helps condition the cooling system, and lubricate the water pump seals. 

To use this sealant, you just need to add the tablets to warm water. It helps stop coolant leaks as well as the internal and external leaks. There are times that you will need to use this sealant in two applications to get the desired results. 

  • ATP AT-205 Re-Seal Stops Leaks.

This product is known to be a safe radiator sealant. It does not only stop leaks but it can also rejuvenate your car’s power steering system, hydraulic system, transmission system, as well as the engine gaskets and rubber seals. Since this sealant has been made and designed to mix properly with synthetic and conventional oils, there is no need to flush the entire system when you add it.   This product promises its users that it will not cause any damage to the car’s internal component but it will effectively stop the leaks and help fix dry and worn out seals. 

  • Genuine GM (12378255) Fluid 3634621 Seal Tablet.

This seal tablet is known to be affordable but it works wonders. This is a ACDelco cooling system seal tablet that consists of an organic and original formation made specifically to be used in the radiator systems. This seal tablet is specially formulated to stop and seal the leaks and prevents leaks from happening as well.  This non-toxic sealant is made with a material that has an ability to seal the system’s cooling porosity that can help prevent corrosion.

  • Interdynamics Certified Engine Cooling Systems UV Dye.

This might be a bit different from all the other products we have mentioned earlier. This cooling system UV dye is not just about sealing the leaks but it can also be convenient in finding out if there is really a leak in your system. 

By adding this product into the cooling system, it will tell you the exact location of the leak in your system and it only needs one application into the system. This cooling system UV dye is also known as a professional grade product. 

To use this product, you need to use a UV blacklight. Aside from the newer and 1996 GM vehicles, this product can be used on different types of vehicles. This product is pretty well-known with a lot of positive reviews and it is also affordable. 

  • Bar’s Leaks 1109 Intake and Radiator Stop Leak.

This radiator sealant can be purchased for a reasonable price. It can stop leaks effectively. It can fix radiator leaks, seal heater core leaks, and other larger leaks. It can also help fix blown head gaskets, blocks, and freeze plug leaks.  It is a one-step kind of a sealer and it has a sodium silicate formula that is known to be compatible with antifreeze. To use this radiator sealant, you will have to drain your cooling system before using it. 

  • BlueDevil Radiator & Block Sealer.

This radiator sealant can seal up all the leaks in your vehicle’s cooling system permanently. It is known to be able to work well on the different kinds of radiators such as copper-brass, aluminum, and plastic radiators. Using this product is also a safe way to seal the leaks permanently. 

The BlueDevil Radiator and Block Sealer is made from a special solid materials formula that is why it is a safe choice. It will not clog or cause any problems in your cooling system. Although it is safe to use, it doesn’t mean that it will be gentle to the leaks. It does its job by binding with metal, aluminum, alloy, or cast iron. It also bonds to the cooling system’s weakest point, making a permanent seal that works well with the vehicle's heat to contract and expand. This product is also compatible with the diesel and gasoline engines. 

A radiator sealant is a fast and great way to stop a radiator leak. It has a lot of benefits such as preventing a breakdown, prolonging major repairs, and extending the life of your vehicle. It can prevent a breakdown since it fixes your leaks that can cause loss of fluid or low fluid levels. We already know what a low fluid level does to a vehicle. It can result in engine overheating which can damage it that can lead to a breakdown. If you know that your radiator is leaking and you can’t afford to have it repaired yet, a radiator sealant can be the solution. It will help seal the cracks or leaks, giving you enough time to prepare for the cost of a radiator replacement.  

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