Pros and Cons of Radiator Stop Leak – The Details

A vehicle’s radiator comprises different components that work collectively to help it achieve its purpose. However, a radiator leak can occur if one of these components goes bad. And because the radiator houses the coolant used to cool your engine, coolant can start escaping due to overheating or leakage and cause many problems – you may have seen a pool of fluid under or in front of your car.

A radiator leak should be fixed quickly to avoid more damage. Here, you will usually need to replace the radiator, which is quite expensive. But you can go for a cheaper option by using a radiator stop leak to seal the leaks. However, many people have often doubted if this sealant works. So here, we will explain how it works and discuss the pros and cons of radiator stop leak.

pros and cons of radiator stop leak

How does radiator stop leak work?

Radiator stop leaks are sealants designed to seal minor leaks in your radiator and other components like your heater core. It usually comes in a bottle of different sizes, which you can pour into your radiator when the engine cools. Then, as the radiator stop leak flows through the radiator, it will seal any small leak it comes across, invariably stopping the leak.

However, there are different manufacturers of radiator stop leaks, each using different ingredients in production. So when buying, ensure the ingredients used corresponds with your car. Thankfully, these manufacturers write the ingredients used on their products to enable you to make a good choice.

Some ingredients used in making radiator stop leaks include sodium silicate, aluminum, copper, iron particles, and fiber and ceramic particles. Each of these ingredients has a way they function, so ensure you follow your manufacturer’s directions on how to use radiator stop leak.

For example, a radiator stop leak made with sodium silicate (also called liquid gas) works when coolant and exhaust gases are leaking simultaneously. And basically, seals leak when exposed to heat between 212-221°F and need about 1490°F heat to provide a strong seal.

In contrast, a radiator seal with fiber and ceramic particles uses nanotechnology to create a stronger seal in the radiator. Creating an almost permanent seal once exposed to heat. While the sealed radiator won’t last long as a new radiator, you can be sure the seal won’t wash away when you do a radiator flush.

Pros and cons of radiator

While radiator stop leak invariably seals leaks, it comes with highs and lows. Let’s see them.

Pros of radiator stop leak

1. Inexpensive and easy to find

Replacing a radiator is generally costly. So you can minimize cost by using a radiator stop leak instead. Even better is that this sealant is easy to get when needed, as you can purchase it at almost every auto part store. However, a radiator leak sealant can only work well on minor coolant leaks.

2. Provide a good seal

At some point, your radiator will break or crack, and a radiator stop leak can seal those cracks, invariably sealing the leaks.

3. Improves safety

A leaky radiator usually lets out fluid, hence reducing your fluid level. Without the right amount of coolant, your vehicle may overheat and cause the car to stop abruptly. This can disorganize your schedule and leave you stranded in a dangerous spot. However, you can avoid all this by simply sealing leaks with an anti-leak coolant.

4. Prevents breakdown

Generally, if you allow your radiator to continue leaking, your engine will suffer from it. Hence, you will notice white smoke from exhaust and it can cause an engine breakdown at any time. So you can help save your engine by applying a radiator stop leak to seal the leaky radiator.

5. Improves performance

With your car’s radiator sealed, your coolant will remain at the right level and works well to cool your engine. A proper functioning engine will usually keep performance intact. Drive with a faulty radiator and see how poor performance will be.

Cons of radiator stop leak

1. Clogging

Stop leak for antifreeze contains powders and pellets. These particles, in turn, get pushed through the cooling system, clogging it.  And often clogging the engine block is quite difficult to clean. Worse is leaving these substances there will destroy your engine.

If your cooling system gets blocked, your coolant will not have a means of distributing coolant, leading to overheating that can cause engine damage.

2. Overheating

The content of the radiator stop leak can block the cooling system, such as the coolant hoses. With this hose blocked, the coolant won’t move to cool engine parts, resulting in engine overheating and complete engine damage.

3. Doesn’t fix leaks permanently

While a radiator leak sealant will help seal minor leaks, they are not a permanent solution. Meaning that there are chances of leaks reoccurring. Additionally, using stop leak in radiator for too long will deposit too much sealant in the system. Invariably leading to more costly radiator maintenance.


Will radiator stop leak hurt my engine?

Radiator stop leak contains powder that can settle in your cooling system and may block it. With the cooling system blocked, your engine will suffer from overheating, invariably ruining the engine. It can also clog the engine block and is very difficult to flush out. So yes, a coolant stop leak may hurt your engine.

Can stop leak clog cooling system?

Yes! Stop leaks contain some particles that get pushed into your cooling system and clog it.

How long does stop leak last in a radiator?

It typically depends on the severity of the leak. If the stop leak is used on minor leaks, it can stay for up to 10-50k miles. If the leak is severe, it won’t last that long and sometimes won’t even work. Another thing that influences how long it stays in the radiator is the product–some products are more effective than some.

So ensure you get from a good brand. One of the best coolant stop leak for radiators you can get on the market is the bar leak stop leak. It seals rubber, aluminum, metal radiator, and other components, and is very durable.

radiator leak

Does radiator stop leak work on hoses?

Radiator stop leak works on hoses. However, it will only provide a temporary seal. It’s just a get-home solution and won’t last for long. You can try using a rubber hose repair tape and replacing your hose instead.

Will radiator flush stop overheating?

Dirty coolant will usually cause overheating. So a radiation flush will keep the radiator working optimally and invariably stop overheating.


The pros and cons of radiator stop leak explained above should guide you in making choices. Truly, radiator stop leak will seal leaky radiator at a low price. However, it could clog your cooling system and engine block and not even provide a permanent fix.

If you want to save cost, you can use them or wed the leaks to avoid all the issues that come with this sealant. However, replacing the radiator will be the best option if money isn’t an issue.


Mr. Rubel is an Engine Mechanic. He has more than 15 years’ experience on repair and maintenance of different kinds of vehicles. He is also providing training to mechanics and works as a Senior Mechanic of a well-known organization. He is sharing his knowledge to support the car lovers to solve the vehicle issues.

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