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Posted: 02/25/2022

Do Radiator Sealants Really Work?

You’re most likely here because you’ve been losing coolant and don’t want to pay the cost of a new radiator. Radiator sealant, also known as radiator leak sealant or stop-leak, can provide a quick fix for coolant leaks, but there are a few things you should know before buying a bottle and trying to stop the coolant leak. We offer a few different varieties of radiator leak sealants below, but take a look over our guide before you buy. Coolant leak repair with stop-leak and similar products is a simple fix, but not a permanent one.


The answer to this question is yes, radiator sealants really do work. However, they are not a miracle solution, and are only good for a temporary fix. Even so-called “permanent” sealants will only last for months, not years. A good radiator sealant can seal all kinds of cooling system leaks. Coolant sealant leak repair can fix the leaks inside a radiator by sealing the pores of the radiator and plugging the point from where you're leaking coolant. When used correctly, a radiator stop-leak can effectively seal mild leaks in the cooling system of a car. Additionally, leaks stemming from the head gasket, engine block, or water pump can be fixed with a sealant. As always, follow the instructions carefully when using a stop-leak like the products offered below.


Radiator Sealants




Are Radiator Sealants Permanent?

While these products work to fix small leaks, they are not a permanent fix for long-term leaks. While some sealants can last for a long time, others may not be as durable, with a radiator sealing only rated for a few hundred or thousand miles. It all depends on the brand and the formulation of the sealant. Ultimately, it is important to read the manufacturer's directions carefully to see how long the sealant is supposed to last. In most cases, however, you will need to reapply the coolant leak repair at some point to maintain your car's cooling system. You'll probably need a professional technician to fix a leaky head and get it repaired properly. As a rule of thumb in car maintenance, if you’ll have to apply a temporary fix more than once or twice, it’s better to fix the source of the problem, but these radiator leak sealant fluids are a great way to make sure you don’t overheat while you’re waiting for your radiator to arrive.


Radiator Sealants



How Long Does a Radiator Sealant Last?

Depending on the severity of the leak, it can last from 10 to 50 thousand miles. In a severe case, the solution may not work at all. If your car continues leaking after you've added radiator leak sealant, you should look for a better radiator repair solution. It may be time to replace the radiator, coolant lines,  head gasket, water pump, thermostat, or other hoses throughout the vehicle. If the leak is serious enough that coolant sealant isn’t doing the job, however, you’ll probably be able to tell where the leak originates.


How to Pick the Right Sealant For Your Vehicle

There are several types of coolant leak repair sealants on the market. To find the right one for your car, read reviews and ratings. Check the formula of the sealant, too. Different formulas will affect your engine differently. When buying a radiator sealant, do your research and make sure you're getting the best possible product for your car. You should look for the one that matches the formula and your needs. Our inventory offers a few different options, let us give you the breakdown to help you choose the right one.


K-Seal Permanent Coolant Leak Repair is renowned for its versatility and ease of use, offering a permanent fix to leaks in the radiator, head gasket, and block with a simple shake-and-pour formula. Unlike traditional sealants that might require specific conditions for optimal performance, K-Seal promises effectiveness in a wide range of scenarios without the need for draining or flushing the system beforehand.


Bar's Leaks presents two distinct formulations: the Radiator Stop-Leak and the Heavy Duty Stop-Leak. The standard Radiator Stop-Leak is designed for quick and easy fixes, suitable for minor leaks and preventive maintenance. It’s a go-to for drivers seeking a reliable solution without significant downtime. On the other hand, the Heavy Duty Stop-Leak is formulated for more severe issues, offering a stronger seal suited for larger systems and more significant leaks. This makes it ideal for older vehicles or those in demanding conditions that may benefit from a more robust fix.


Blue Devil's Pour-N-Go Radiator & Block Sealer stands out for its non-clogging formula that permanently seals leaks in plastic, aluminum, and metal radiators, heater cores, blocks, and heads. Unlike some sealants that might risk clogging or damaging cooling systems, Blue Devil emphasizes safety and effectiveness, even in vehicles with a history of overheating. This product is particularly appealing for those who prioritize a balance between strong sealing capabilities and maintaining the integrity of their vehicle’s cooling system.


Radiator Sealants



Your Vehicle Part Source

Arnold Motor Supply has been a leading supplier of auto parts since 1927. Founded and based in Iowa,  we have locations all over the midwest. Order your parts today and you'll be notified via email once your purchase is ready for pickup at your local Arnold Motor Supply or Auto Value parts store.


Frequently Asked Questions

Can radiator leak sealant fix all types of coolant leak?

Radiator leak sealants are designed to seal minor to moderate leaks in radiators, heater cores, and gaskets. While highly effective for these applications, they may not be suitable for fixing large cracks or damage to other parts of the cooling system. Always assess the severity of the coolant leak and consult a professional if there’s extensive damage.

How long does it take for radiator leak sealant to work?

Most radiator leak sealants begin working almost immediately upon application. However, the exact time can vary depending on the product and the severity of the leak. Typically, you can expect results within a few minutes to several hours after application. For the best results, follow the manufacturer's instructions regarding the engine's running time after application, provided on the bottle.

Is radiator leak sealant a permanent fix?

Some products, like K-Seal Permanent Coolant Leak Repair, are designed to offer a permanent solution to leaks in the cooling system. However, the permanence of the repair can depend on the leak's size and location. In some cases, mechanical repair might be necessary for a long-term solution.

Can I use radiator leak sealant in any type of vehicle?

Most radiator leak sealants are compatible with a wide range of vehicles, including cars, trucks, and motorcycles, and work with all types of coolant. However, it's important to check the product's compatibility with your vehicle's specific make and model, as well as with the type of coolant you are using.

" style="font-size:large">Will using a radiator leak sealant clog my cooling system?

Quality radiator leak sealants are formulated to seal leaks without clogging the cooling system. Products like Blue Devil Pour-N-Go emphasize their non-clogging formula. Following the product's instructions carefully is important to avoid potential issues.



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