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A pool of green or other colored watery liquid under the very front of your car is a sure sign that you have a coolant leak, and a good possibility a radiator leak. Sometimes, these leaks are in conjunction with an overheating issue, and other times, they are not. Replacing your radiator can sometimes be a costly project. Thankfully, there are radiator stop leak products to help seal radiator some leaks. Does radiator stop leak work? Find out today how this product works and whether you can use it to solve your leaking issues.

What Is Radiator Stop Leak?

Radiator stop leak is a common additive that is designed to seal minor leaks in your radiator and leaks in-between components. While it’s an aftermarket additive, some car manufacturers use it on new radiators to improve the seal between new radiator components.

While there are a range of radiator stop leak products available, they all use the same basic chemistry. Here are common components found in most radiator stop leak additives:

  • Ceramic fibers and particles
  • Sodium silicate
  • Aluminum, copper and iron particles

You won’t necessarily see all of these ingredients in a single radiator stop leak product. Some include other ingredients that target other common radiator issues or assist these particles and fibers in forming a seal. Ask 10 “Car folks” and you are bound to get a 10 different answers on Stop Leak and a myriad of other “homebrew” items to stop a leak – black pepper, crushed almonds, an egg….the list goes on and on.

How Does It Work?

Each type of radiator stop leak works in a slightly different way. While the end result is similar, filler particles, ceramic fibers, and sodium silicate all attempt to seal by hardening and solidifying where the leak is occurring. Another area that Stop Leak can help is with your car’s Heater Core. A Heater Core is basically a small radiator inside the cabin of the car, that radiates engine heat for heat in the winter. Heater Cores can suffer leaks similar to a radiator, and are much, much more labor intensive to repair.

Fillers, whether ceramic, metallic, or organic, circulate through your radiator and are forced into the gap in your radiator piping when the system is under pressure. These particles bind and create a temporary seal. Once you flush your coolant or even top off your coolant, you may flush out enough filler to remove the seal and form another pinhole leak.

Instead, ceramic fibers use what’s called a micro-sphere nano-technology approach to create a more fibrous patch in your radiator. Once heated, these fibers cure and create a semi-permanent seal. It may not be as durable as a brand-new radiator, but it can withstand flushing your coolant without breaking the seal.

Finally, sodium silicate, also known as liquid glass, melts at around 212 to 221 degrees Fahrenheit. As the liquid circulates your cooling system, it reaches a leak in a hot portion of your engine. Once it reaches the correct temperature, it melts to form hard seal. Sodium silicate requires temperatures up to 1,490 degrees Fahrenheit to melt again, so it creates an extremely strong seal.

Find out how to use radiator stop leak and when you can effectively use it. Some leaks can’t be effectively sealed with radiator stop leak. In these situations, your radiator needs to be repaired or replaced in order to form a proper seal.

Stop Leak vs. Radiator Repair

It’s important to understand that stop-leak is usually only a temporary solution, or a solution to a minor leak. Why is there a leak in your radiator? Stop leak additives may seal the pinhole leak in your radiator, but they may not deal with the source of the damage. Keep in mind, old coolant can encourage corrosion inside your radiator and other parts, so it’s important to service/change/flush your cooling system on a regular interval. Not only will all this corrosion and buildup damage the internal passages of your radiator, it may clog your radiator completely. Most modern radiators are an aluminum core with 2 plastic end tanks on each side. Most failures occur when the tank’s rubber seals corrode and end up seeping antifreeze. On older copper/brass radiators, pinholes were very commons and stop leak was a good sealer.

If there are multiple leaks, or if there’s a leak in an area that radiator stop leak can’t seal, it’s time for a replacement radiator. Stop by your local AutoZone to find affordable parts for a DIY repair or select one of our preferred installers for your radiator.

It’s also important to note that many radiator sealers and block sealers require you to complete drain and flush all your coolant, and add the Stop Leak or Block seal with pure water to run for a brief period of time. Be sure to read the instructions thoroughly. An improperly maintained radiator may need to be flushed before you seal it anyways. A single pinhole may be easy to seal, but it also may be a sign that other areas of your radiator are damaged and may soon leak. Flushing your system, as stated before, should be a regular maintenance item.

Why Isn’t Stop Leak Working?

While stop leak can create a reliable seal in a number of areas in your cooling system, there are many situations where it won’t work properly. A bad leak between the end tanks of the radiator, a hose leak, coolant reservoir tank, or water pump are not going to seal. If these parts have a leak, they will need to be replaced. No amount of radiator stop leak can protect these areas from a minor or major leak.

These areas can’t be sealed by stop leak, so you’ll need to replace a part to restore a proper seal. No amount of radiator stop leak can protect these areas from a minor or major leak.

Another common issue with radiator stop leak is when it forms a complete seal in your radiator. This side effect is typically caused by overuse. Carefully read the directions on your radiator stop leak package. Every company uses a slightly different strength and filler material combination, so it’s essential to only add the precise amount of stop leak necessary and make sure you read whether the mixture can be added to antifreeze, or needs pure water.

Using stop leak, particularly an additive that relies on fillers, is a short-term solution at best. Stop by AutoZone to see about finding a replacement part or more permanent sealing solution to keep your radiator operating effectively.

What Other Stop Leak Options Are Available?

Similar to radiator stop leak, there are chemicals made for other systems like AC stop leak, head gasket stop leak and oil stop leak products. These each have their own limitations but can be used as short-term sealants in their relative systems. Just like radiator stop leak, other stop leak additives can be a good option if you need an emergency seal and can help you avoid replacing a major component for some time, but remember, it’s likely that component will, over time, need replacement.

Where Can I Buy Radiator Stop Leak?

Now that you know how to use radiator stop leak and how it works, you might wonder, “What is the best radiator stop leak?” There are a number of name-brand radiator stop leak products on the market. The best option depends on your vehicle and your particular leak, so shop for stop leak additives at your local AutoZone to compare options.

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