The Best Radiator Stop Leak: For the Quickest Repairs

Your car’s radiator can be quite tricky to handle. Since it’s dealing with the cooling system, it is prone to a lot of problems, most notably leaking. The reason for this is that your car’s cooling system mainly relies on liquid substances. Great examples of this are motor oils and water.

Letting the radiator leak for too long can spell disastrous consequences. Hence, it’s important that you have the best radiator stop leak at your disposal. That will patch up your radiator efficiently. In return, it’ll also save you so much money compared to going to a repair shop!

Picture
Reasonable Price
K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak...
Bar's Leaks 1194 Grey Radiator Stop Leak - 6 oz.
J-B Weld DS-114 PERM-O-SEAL Radiator Stop Leak - 0.7 oz.
Genuine GM Fluid 3634621 Cooling System Seal Tablet - 4 Grams,...
Best Pick
ATP AT-205 Re-Seal Stops Leaks, 8 Ounce Bottle
Type
Multi-purpose liquid sealant type
Radiator liquid sealant type
Compound material sealant type
Tablet sealant type
sealant type
Best For
Engine block, cylinder head, and small-moderate radiator leaks
Radiator leaks of all sizes
Best for pool, pond, engine block, heater core, and smaller radiator leaks
Best for microscopic radiator leaks
And cooling system components
Unique Feature
Long effectiveness, does not wear down quickly
2X Concentrate formula gives it superior sealing prowess
Compound material allows it to stick firmly to minor radiator leaks
Tablet dissolves which enable it to tend to the smallest holes invisible to the naked eye
Uses from the engine down to differential and chassis applications
Rating
4.7
4.8
4.6
4.8
4.7
Reasonable Price
Picture
K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak...
Type
Multi-purpose liquid sealant type
Best For
Engine block, cylinder head, and small-moderate radiator leaks
Unique Feature
Long effectiveness, does not wear down quickly
Rating
4.7
Picture
Bar's Leaks 1194 Grey Radiator Stop Leak - 6 oz.
Type
Radiator liquid sealant type
Best For
Radiator leaks of all sizes
Unique Feature
2X Concentrate formula gives it superior sealing prowess
Rating
4.8
Picture
J-B Weld DS-114 PERM-O-SEAL Radiator Stop Leak - 0.7 oz.
Type
Compound material sealant type
Best For
Best for pool, pond, engine block, heater core, and smaller radiator leaks
Unique Feature
Compound material allows it to stick firmly to minor radiator leaks
Rating
4.6
Picture
Genuine GM Fluid 3634621 Cooling System Seal Tablet - 4 Grams,...
Type
Tablet sealant type
Best For
Best for microscopic radiator leaks
Unique Feature
Tablet dissolves which enable it to tend to the smallest holes invisible to the naked eye
Rating
4.8
Best Pick
Picture
ATP AT-205 Re-Seal Stops Leaks, 8 Ounce Bottle
Product Name
Type
sealant type
Best For
And cooling system components
Unique Feature
Uses from the engine down to differential and chassis applications
Rating
4.7

Last update on 2018-02-17 at 10:38 PST - Details

Understanding the Cooling System

Before we dive into the products, it’s a must for us to understand the cooling system and how the radiator works. Without any knowledge towards this, you might feel uneasy buying a stop leak. It could make you think twice and resort to professional service.

While there’s nothing wrong with that, leakage in your cooling system is one of the problems that can be solved by yourself. That would improve your skill as a car owner, and will also save you a lot of time and money!

Unlike other systems in your vehicle’s engine, the cooling system is one of the simplest components that is easy to understand. That’s why it’s a must for any car owner to know at least this much.

For starters, the cooling system only does one thing, and it’s pretty significant. Obviously, it’s there to cool your car while at work. Cars use air-fuel combustion and a lot of mechanical friction. Thus, your car is bound to overheat if it doesn’t have a functioning cooling system.

The system begins by having a cap where you place the cooling agent. It is the entry point of the coolant for it to reach the deeper areas in the engine. The coolant is something that you can buy separately.

You can locate the cap by the engine block. And after reaching its entry point, it gets fed to an inlet hose mounted on top of the radiator. The coolant then travels to several passages strategically to cool the engine. Some of the most important passageways that it goes to are the engine block and cylinder heads.

As the coolant travels throughout the engine, it cools it down by absorbing the heat. Remember, instead of neutralizing the heat, it absorbs it. This way your engine doesn’t steam and create gas. Finally, the heated fluid will travel back to the radiator for it to come out.

Significant Parts of the Cooling System

To further expound this, it’s best to know that like any component in your car; the cooling system has several parts. These all work to create a functional and systematic way to cool your car’s engine.

Radiator

The radiator is arguably the most crucial part of your engine’s cooling system. If you say that you have a problem with the cooling, most mechanics will check the radiator immediately.

Radiators, to just put it, are heat exchangers. They’re like money exchangers, except the currency here is the heating temperature. After the coolant absorbs the heat throughout the engine block, it goes to the radiator to exchange all that heat.

The transfer happens thanks to the fins inside your radiator. The hot liquid travels through the tubes of the radiator, where the fins will absorb the heat. That, in turn, will allow the coolant to lower its temperature substantially. It will allow it to repeat the cycle of cooling.

Water Pump

The water pump is pretty simple to explain too. It’s a medium-sized device that is mainly responsible for circulating the coolant. Without the water pump, there will be a big problem when it comes to the cycle’s process.

Thus, look out for potential water pump issues as well.

Thermostat

You can take the thermostat’s function. Like other applications, the engine’s thermostat measures the temperature of the coolant. It acts as a signal if the temperature of the coolant is good enough to enter the radiator.

If the coolant is not yet hot enough, the thermostat won’t allow it to pass. That benefits the cooling efficiency of your car, making sure that it absorbs the heat very well.

Other Things to Remember

The parts that we’ve listed are not all there is to the cooling system. Parts such as the pressure cap, reservoir, freeze plugs, and gaskets are all important. However, we won’t be focusing much on that for today.

Still, always conduct regular check up on your cooling system in general. Doing the correct protocol and procedures should lessen the probability of your cooling system from malfunctioning.

How Do I Handle Radiator Leaks?

Leaks can happen quite frequently in most cars, especially ones with a lot of mileage. One of the most common places for this to occur is your radiator, and that’s because it takes in a lot of hot fluid.

Having leaks in your radiator can have a lot of consequences. The good news is that it’s easy to identify leaks and solve them.

Checking for Leaks

For starters, it’s important that you inspect several details about your car. The first you’d want to do is to check the temperature gauge to see if it’s rising. Should there be a leak in the radiator, this will mean the loss of coolant. Less coolant will eventually cause temperatures to rise.

Another means to do this is to check if there are any puddles under the radiator. It is the most visible sign since a leaking radiator would produce a puddle of coolant beneath it when idle.

If you’re still not sold on that, you can further inspect it by looking at the reservoir. It is also part of the cooling system, and it stores coolant inside a transparent container. Start by marking the coolant inside.

Afterwards, if you go for a drive, you might see that the coolant has reduced inside the container. That shouldn’t happen since coolants are meant to circulate, not reduce. Thus, a leak is the only reason for this to happen.

Using the Radiator Stop Leak

The products we are about to discuss now are not great solutions for serious problems. These issues include blown gaskets and radiators with huge cracks. Instead, the stop leak works through minor to moderate cracks that are usually caused by wear and tear.

The major problems, on the other hand, are caused by external factors such as accidents. The stop leak will travel inside the radiator, and this works by repairing the interior by detecting gaps.

Once the holes are exposed, the substances in the stop leak will automatically stick to it and repair it. It’s really like a live material that reacts to the presence of air gaps. Thus, it’s suitable for paper thin leaks and not the major ones.

Our Top 5 Picks

K-Seal opens up our list not just as a radiator stop leak, but as a multi-purpose one. Buying multiple stop leaks for different components can cost you. However, K-Seal does a great job by applying the principles of radiator stop leak to other parts of your car

We like

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    Coolant leak repair is permanent
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    It lasts a long time, and if your vehicle only has minor to moderate leaks, it should be permanent
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    Extremely versatile
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    It makes applies the principles of patching up a radiator leak so you can use it for other components.
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    Example of where you can place this is in the head gasket, the cylinder heads, heater core, and even the engine blocks
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    It mixes with all types of antifreeze which ensure you that it won’t fail as a sealant
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    Very easy to use
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    Just shake, pour, and wait for it to set

We do not like

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    It can make the coolant look dirty after use
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    It’s not particularly good at sealing water pump problems

Bar’s is probably one if not the most famous innovator of radiator stop leaks. Unlike the K-Seal, Bar’s had focused heavily on improving radiators instead of making it multi-purpose.

Some of the things you’d like about this stop leak are that it one bottle can treat up to 3 gallons. That’s a lot of money that you’ll save. Moreover, Bar’s has made a name for being a trusty quick repair option for those with radiator leaks

We like

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    2X Concentrate solution gives it a powerful sealing feature
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    The solution allows the substance to penetrate through the tiniest cracks and seal it completely
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    Works well with all types and colors of antifreeze
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    Top notch versatility
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    Although not stated as multi-purpose, Bar’s stop leak can fix pools, ponds, and also heater cores.

We do not like

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    The quantity might not be enough for some car owners
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    It will benefit more for clearer instructions for non-radiator use

J-B Weld enters our list with a unique take on their radiator stop leak. The previous two products are all bottled upon manufacture. However, J-B Weld’s have a more convenient approach by packaging their stop leaks like super glues.

Instead of a huge bottle, you get little packets of tubes which you can choose from single up until a dozen pieces. Inside are compounds instead of liquids, which acts more like putty towards the cracks.

We like

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    Unconventional compound material can be a better solution
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    J-B Weld’s makes use of sticky material that covers the smallest leaks in your radiator
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    Versatile product
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    Besides sealing, the compound material can prevent rust inside the heater thanks to its solid construction
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    Easy to use
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    It uses the same principles as the liquid products by just pouring it inside the radiator

We do not like

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    The compound material does not set as quickly as the liquid ones
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    It can make the insides a little dirty

Coming in at fourth on our list is another innovative take on the traditional radiator stop leak. This time, Genuine GM makes use of tablets, almost similar to medicinal ones. These tables will dissolve inside your radiator, allowing it to seal the leaks.

We like

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    Very sustainable tablet sealant
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    Each package has five tablets weighing four grams each. That gives you a lot of ease and convenience regarding portion-control.
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    Very clean and does not leave any residue
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    The small tablets dissolve quickly and do not stain your vehicle’s cooling system
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    It works best for repairing micro leaks
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    Since the tablet dissolves into microscopic granules, these allow it to fix the smallest of cracks as well.

We do not like

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    Not the best sealant for moderate to large-sized leaks
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    Then, it has unmatched effectiveness, but it wears out pretty quickly too
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    It can stop the leaking for a few weeks or maybe a month or two only

The ATP Automotive company is our second brand that introduces a holistic approach to stop leaks. Similar with K-Seal, ATP presents its stop leak formula that’s capable of sealing almost all automotive parts.

We like

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    Innovative solution that repairs efficiently
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    Besides sealing the cracks, the Re-Seal stop leak also rejuvenates gaskets and other rubber seals
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    The formula uses the principle of a plasticizer, which hardens material and makes it flexible
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    It’s completely toxic-free and petroleum distillate-free​​​​
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    That prevents any wear or stain in any part of your car
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    Sets quite fast in under 5 hours only, perfect for emergency situations

We do not like

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    Try to avoid using this for transmission leaks as it can clog up the gears
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    It wears off over time
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    Similar to GM Genuine, this is suitable as an emergency stop leak

Our Verdict

While we do have a lot of great products out here, finding the best radiator stop leak is a matter of trial and error. It’s important for you to understand that not all products can work miraculously for all vehicles.

A lot of things depend on the degree of damage, the size, and even the model of the vehicle itself. However, if we’re going to go with the most well acclaimed product, ATP Re-Seal wins this one.

They’re one of the best at formulating straightforward solutions to help stop those leaks once and for all. So go ahead and give it a try! If you find this informative, be sure to leave a comment below and share this to fellow car owners. Good luck!

Thomas Roberge
 

This website was created and is supported by a person who has been in the business of working with power tools, dedicated to home improvement projects both professionally and for the do it yourself type of person.

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