The Best Radiator Sealers

Looking for the best Radiator Sealers?

Discover now our comparison of the best Radiator Sealers. It is never easy to choose from the wide range of offers. On the market, you will find an incalculable number of models, all at different prices. And as you will discover, the best Radiator Sealers are not always the ones at the highest prices! Many criteria are used, and they make the richness and relevance of this comparison.
To help you make the best choice among the hundreds of products available, we have decided to offer you a comparison of the Radiator Sealers in order to find the best quality/price ratio. In this ranking, you will find products listed according to their price, but also their characteristics and the opinions of other customers. Also discover our comparisons by categories. You won’t have to choose your products at random anymore.

No. 1

Bar's Leaks 1109 Liquid Copper Block Seal, Intake and Radiator Stop Leak, 18 oz. | One Step, Safe for All Cooling Systems

PERMANENTLY FIXES COOLING SYSTEM LEAKS: . One step formula permanently repairs coolant loss problems on cars, trucks, vans, SUV’s and RV’s.
ANTIFREEZE COMPATIBLE - NO DRAINING REQUIRED: Antifreeze compatible sodium silicate liquid glass penetrates large and small leaks in plastic, aluminum and cast iron heads, blocks, intake manifold & gaskets, freeze plugs, heater cores and radiators.
ONE STEP - POUR DIRECTLY INTO RADIATOR - EASY TO USE: Fiber additives lock together with liquid to increase strength and promote a permanent seal. It will not harm the coolingsystem when used properly, no draining is required.
USE WITH ALL TYPES OF TRADITIONAL OR EXTENDED LIFE COOLANT: Use with ALL types of traditional or extended life coolant including yellow, orange, pink, red, blue, purple and green silicate based & non-silicate based (OAT/HOAT) 50-50 mix antifreeze, and/or water.

SaleNo. 2

K-Seal ST5501 Multi-Purpose One Step Permanent Coolant Leak Repair, 8oz, Pour and Go, Mixes with All Antifreeze, No Flushing Required

FIX IT FAST: Our multi-purpose solution works in minutes to quickly & permanently seal leaks in the radiator, head gasket, freeze plugs, block, heater matrix & water pump. Fixes most leaks in water-cooled engines
STOP HOLES & CRACKS: With just 1 step our unique formula will seek out each hole & crack, permanently sealing them, without any adverse impact on the efficiency of your engine cooling
EASY TO USE: K-Seal couldn't be simpler to use & requires no draining or flushing; just shake, pour & go - shake the bottle, add the fluid to your coolant system & run your engine as normal
VERSATILE COMPATIBILITY: Compatible with all types of antifreeze coolant. Suitable for use in both cars & light trucks with up to 12 cylinders. A permanent repair for the lifetime of the engine
PROFESSIONAL-GRADE RELIABILITY: Trusted by mechanics, our sealer delivers a durable & long-lasting repair. A cost-effective solution to engine coolant leaks, enhancing the reliability & performance of your vehicle’s cooling system. We've sold millions worldwide & are independently verified by university testing to meet ASTM D3147

No. 3

Bar's Leaks Radiator Stop Leak, 11 oz

DISSOLVED PELLETIZED FORMULA: Bar’s Leaks Radiator Stop Leak seals internal, external and coolant-to-oil leaks. It is specially formulated to seal larger leaks better than other stop leak products.
STOPS CURRENT AND FUTURE LEAKS: Works safely and effectively on plastic, aluminum and metal radiators, heater cores, blocks, heads, gaskets and freeze plugs.
INHIBITS RUST AND CORROSION: Water Pump Lube lubricates water pump seal and inhibits the formation of rust and scale.
WORKS WITH ALL TYPES AND COLORS OF ANTIFREEZE COOLANT AND / OR WATER: Compatible with both conventional silicate-based and extended life (OAT/HOAT) antifreeze, all types and colors. Can also be used in straight water.
Bar’s Leaks Radiator Stop Leak seals internal, external and coolant-to-oil leaks. It is specially formulated to seal larger leaks better than other stop leak products.

SaleNo. 4

Super Glue Pro Seal N62020 Instant Gas Tank and Radiator Repair

Instant Gas Tank and Radiator Repair
0.7-Ounce strip
Easy to use putty
Permanently seals cracks and split seams
Hardens like steel

SaleNo. 5

J-B Weld 2120 Radiator Repair Kit

RADIATORWELD: Our radiator and plastic tank repair kit has all you need for making professional quality, permanent repairs with state of the art components and easy to follow instructions.
COUNT ON US: For more than 40 years, our products have earned a loyal following from people who take pride in their work. With each product we innovate, we continue to provide the world's strongest bond for your projects.
SIMPLE TO USE: No removal of tank or radiator is required to stop leaks. Easily fix holes up to 3/8" diam. or cracks up to 4" long. Includes epoxy putty, fiberglass cloth, sandpaper, and applicator.
VERSATILE & DEPENDABLE: Great for radiators, washer fluid tanks, storage tanks, water tanks, plastics, composites, PVC and more. Professionals, mechanics and avid DIYers know J-B gets the job done.
NO PROJECT TOO BIG OR TOO SMALL: We have all the products you need to get the job done right. JB Weld always delivers the legendary performance of the World's Strongest Bond.

SaleNo. 6

K-Seal ST5516 Heavy-Duty Multi-Purpose One Step Permanent Coolant Leak Repair, 16 oz, Pour and Go, Mixes with All Antifreeze, No Flushing Required

FIX IT FAST: Our multi-purpose solution works in minutes to quickly & permanently seal leaks in the radiator, head gasket, freeze plugs, block, heater matrix & water pump of heavy duty vehicles. Fixes most leaks in water-cooled engines
STOP HOLES & CRACKS: With 1 step our unique formula will seek out each hole & crack, permanently sealing them, without any adverse impact on the efficiency of your engine cooling
EASY TO USE: K-Seal couldn't be simpler & requires no draining or flushing; just shake, pour & go - shake the bottle, add the fluid to your coolant system & run your engine as normal
HEAVY DUTY PERFORMANCE: Engineered for large engines & industrial use; suitable for commercial or agricultural vehicles. A permanent repair for the lifetime of the engine. Compatible with all types of antifreeze coolant
PROFESSIONAL-GRADE RELIABILITY: Trusted by mechanics, our non-corrosive sealer delivers a durable & long-lasting repair, without clogging your cooling system. A cost-effective solution to engine coolant leaks, enhancing the reliability & performance of your vehicle’s cooling system. We've sold millions worldwide & are independently verified by university testing to meet ASTM D3147

No. 7

Visbella Radiator Stop Leak Sealer Conditioner Radiator Repair Kit Car Heater Core, Freeze Plugs, Cooling System & Radiator Repair (Tube, pcs, 1)

Engineered by automobile and chemistry experts, this Radiator Stop Leak Sealer ensures your car's cooling system runs smoothly
Safe for all metals, plastics, rubbers, aluminum, hoses and connections, it's the guardian your radiator needs
Compatible with all antifreeze types, this Leak Sealer Conditioner not only stops leaks but prevents rust and lubricates the water pump
Our Radiator Sealant offers an affordable solution to prevent and repair cooling system damage, saving you time and money
One step formula -pour directly into radiator- permanently repairs coolant loss problems on cars, bus, trucks, vans, SUV’s and RV’s

No. 8

CRC K&W 401016 Block Seal Permanent Metallic™ Block & Radiator Seal - 16 Oz

Permanent molecular seal that’s as strong as steel
Seals cracks & holes in cast iron and aluminum engine blocks, head gaskets, freeze plugs, and copper, aluminum and bi-material radiators & heater cores
For use in all water-cooled diesel and gasoline vehicles
Withstands extreme pressure and temperatures of a cooling system and will not wash away
Professional grade formula exceeds ASTM D6107 for effectively sealing leaks in cooling systems

No. 9

BlueDevil Products 00205 Radiator & Block Sealer - 16 Ounce

Permanent repair for radiator and block leaks.
Works effectively on plastic, aluminum and/or metal radiators
Contains no solids or fibrous materials.
Safe and Easy to use.
Guaranteed

No. 10

Irontite All Weather Seal, Blue, 16 oz

Permanent Leak Sealant for Cooling Systems: Irontite All Weather Seal creates a permanent seal in head gaskets, radiators, heater cores, and other parts of the cooling system, effectively preventing leaks.
Works with All Types of Antifreeze: This versatile formula is compatible with traditional antifreeze, waterless antifreeze, and various proprietary coolant types, ensuring a perfect fit for any vehicle.
No Sludge or Clogging: Unlike many other stop-leak products, All Weather Seal won’t cause sludge buildup or clog heater cores, maintaining the performance of your vehicle’s cooling system.
Easy to Use & Compatible with Multiple Materials: This formula is safe for use with aluminum, cast iron, steel, and plastic components, making it a reliable solution for various vehicle types and cooling systems.
Activates with Heat & Air: Once added, All Weather Seal activates when the cooling system reaches operating temperature, efficiently sealing leaks without interrupting the flow of coolant.
Ideal for Preventative Maintenance: Perfect for everyday vehicles, commercial trucks, and heavy-duty machinery, this product is a great preventative measure to keep cooling systems leak-free and running smoothly.

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Last update on 2025-07-04 / Affiliate links / Images from Amazon Product Advertising API

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