Best Heater Core Leak Sealant in 2023: Our Top 15 Picks

Sometimes it might be quite difficult to find the best heater core leak sealant. With every niche market offering so many different products, it makes sense that this is the case.

Unfortunately, this very fact can make it incredibly difficult to find the item that best suits your needs, which is why we’ve put together this heater core leak sealant buying guide.

Our 15 Favorites:

15 Top Heater Core Leak Sealant Reviews:

SaleBestseller No. 1
Bar's Leaks 1186 Liquid Aluminum Stop Leak - 16.9 oz , Gray
  • Bar's Leaks Liquid Aluminum Stop Leak seals radiator leaks. Seals freeze plug leaks. Repairs gasket leaks and heater core leaks. Lowers water temperature.
  • Seals radiator leaks
  • Seals freeze plug leaks
  • Repairs gasket leaks
  • Special Shipping Information: This item cannot be returned and has additional shipping restrictions
SaleBestseller No. 2
K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak Repair , BLUE
  • Permanent Coolant Leak Repair - Just Shake, Pour And Go.Fit Type: Universal
  • Mixes With All Antifreeze
  • No Draining Or Flushing
  • Fixes Cracks And Leaks In Radiator, Head Gasket, Freeze Plugs, Cylinder Heads, Heater Core, Water Pump Casing And Engine Blocks
Bestseller No. 4
Prestone AS145 Stop Leak Repair for Radiators, Heater Cores, and Hoses, 11 oz, 1 Pack
  • Patented formula quickly stops leaks in radiators, water pumps, and heater cores
  • Boosts corrosion inhibitors to protect against pitting and corrosion, which cause radiator leaks
  • Combination of natural and synthetic components provides the ability to seal leaks up to 0.020" x 0.5"
  • Seals even large leaks without interfering with the flow through the radiator or heater core
  • Stops the leak as well as the corrosive condition that causes it
Bestseller No. 5
Bar's Leaks 1109 Block Seal Liquid Copper Intake and Radiator Stop Leak - 18 oz.
  • Seals larger leaks seals
  • Repairs heater core leaks
  • Repairs freeze plug leaks
  • Repairs blown head gaskets
  • Repairs blocks
Bestseller No. 6
Bar's Leaks Radiator Stop Leak 2X Concentrate, 6 oz.
  • Product type :Auto Accessory Stops and seals coolant leaks
  • Package dimensions :4.064 cm L x6.096 cm W x12.446 cm H It has double the power of most other stop leak products and saves
  • country of origin :United States coolant and/or water. One bottle treats systems
  • package weight :0.81lbs Works with all types and colors of antifreeze That’s why we created the Bar’s Leaks Radiator Stop Leak 2X Concentrate.
  • Seals Leaks in Radiators, Gaskets, Heater Core & Freeze P lugs Works with all types and colors of antifreeze coolant
SaleBestseller No. 7
J-B Weld 8277 WaterWeld Epoxy Putty Stick - 2 oz.
  • J-B WELD WATERWELD: A hand mixable two part epoxy putty stick, that can cure under water and is ideal for repairing plumbing, fuel tanks, tubs and showers, drains, pool and spa, boats & potable water tanks and more! J-B Weld WaterWeld is certified by the NSF and is safe for contact with potable water.
  • CURE AND SET TIME: After kneading the two part formula together by hand, WaterWeld takes 25 minutes to set and cures in 1 hour. J-B Weld WaterWeld set and cure color is off white.
  • PRODUCT FEATURES AND STRENGTH: J-B Weld WaterWeld has lap shear strength of 1300 PSI, can withstand continuous temperatures up to 300F (149C) and intermittent temperatures of 350F (176 degrees Celsius) and is chemical resistant against petroleum, hydraulic fluids and other chemicals when fully cured.
  • SURFACE APPLICATIONS: Iron & Stainless Steel, Copper & Brass, Aluminum & Bronze, Fiberglass and Plastic & PVC.
  • DO IT YOURSELF: Big or small, you can DIY it with J-B Weld. Our heavy duty epoxy and adhesives repair & restore it right the first time. J-B Weld delivers superior performance, quality, and results for the World’s Strongest Bond.
Bestseller No. 8
BlueDevil 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
SaleBestseller No. 9
K-Seal ST5516 HD Multi Purpose One Step Permanent Coolant Leak Repair
  • Permanent coolant leak repair - Just shake, pour and go
  • Mixes with all antifreeze
  • No draining or flushing
  • Fixes cracks and leaks in radiator, head gasket, freeze plugs, cylinder heads, heater core, water pump casing and engine blocks
  • If product did not seal head gasket leak, the system might be Over-pressurized, which causes back pressure and doesn't allow the product to reach the problem area, on this page below under Technical Specification is a PDF Guide with instructions to follow to complete the repair successfully
Bestseller No. 10
Bar's Leak HG-1 HEAD SEAL Blown Head Gasket Repair
  • Repairs Blown Head And Intake Gasket Leaks
  • Seals Cracked Cylinder Heads And Blocks
  • Stops Heater Core And Radiator Leaks
  • Fixes Leaking Freeze And Core Plugs
Bestseller No. 11
ACDelco GM Original Equipment 10-108 Cooling System Sealing Tabs - 4 g (Pack of 5)
  • Engineered for use on a variety of engine components - effective on: oil pan, ladder frame, front and rear covers, t-joints, manifold corners, intake, manifold end seals, and cam covers
  • Designed for quick and easy application, assembly may be filled with oil or coolant immediately after applying sealant and torqueing the bolts
  • High viscosity product that cures when exposed to air
Bestseller No. 12
Permatex 82099 Spray Sealant, 12 oz.
  • Durable rubber barrier stops leaks in minutes
  • Targets low pressure leaks in hoses, oil pans, differentials, transmission pans, as well as plastic, PVC and metal pipes
  • Eliminates the need for liquid additive sealers that can swell and foul internal seals
  • Seals hard-to-reach leaks without the need for disassembling or removing parts
  • Resists common shop fluids
Bestseller No. 13
K-Seal ST3501 Pour and Go Permanent Head Gasket and Block Repair, 16 fl. oz
  • Just Pour & Go – No Need for Expensive Head Gasket Repairs.Fit Type: Universal Fit
  • Fixes blown head gaskets, cracked heads and blocks
  • A permanent repair, guaranteed for the lifetime of the engine
  • The Safe and Easy Way to Fix a Coolant Leak
  • Scientifically Tested - K-Seal is the only product to have been successfully tested by the equipment at Brighton University and classes as meeting the demands of ASTM D3147.
Bestseller No. 14
Henkel 908570 2.7 oz Tub Clear Silicone Waterproof Sealant, Single Tube
  • Use for sealing or repairing door frames, windows, vents, toys, appliances, gaskets, weather-stripping, outside of fireplace doors, shoes and boots
  • Bonds ABS, glass, ceramic, porcelain, wood, aluminum, stainless steel, cultured marble, fiberglass, granite, vinyl tile, some rubbers and plastics
  • Aquarium safe
  • No cracking, peeling or shrinking
  • 2. 7 oz.
Bestseller No. 15
Dorman 626-001 Engine Heater Core Bypass Kit
  • Cost-effective fix - this heater core bypass kit offers an affordable alternative to replacing an entire failed heater core
  • Complete solution - contains components and hardware required to bypass a leaking or failed heater core, including interchangeable 5/8" and 3/4" hose fittings to adapt to most common heater hoses
  • Durable materials - the components in this kit are manufactured from quality materials for reliable service
  • Trustworthy quality - vehicle try-on tested, and backed by a team of product experts in the United States and more than a century of automotive experience

Last update on 2023-01-12 / Affiliate links / Images from Amazon Product Advertising API

How to find the best heater core leak sealant?

Here, we’ll be going over a number of factors that you can use to ensure that you’re purchasing the best heater core leak sealant for you.

Regardless of which type of item you’re looking to buy, chances are that there are existing buying guides on the internet, all of which aim to give you good heater core leak sealant recommendations.

Despite these recommendations, however, it’s always a good idea to do your own research. In addition to this research, asking yourself the following questions is also super helpful:

  • What features does the heater core leak sealant need to have to be perfect for my needs?
  • What is my budget?
  • Do I need to purchase a certain brand?

Once you’ve answered these questions and have a good idea of what you’re looking for and the buying process becomes much easier. Keep in mind that when looking for the best product, there’s no need to rush. In fact, very rarely are the ideal products found by choosing the first one you see or by basing your decisions on only one factor. Take your time and enjoy the process!

Now, with the answers to the previous questions in mind, we urge you to use our upcoming buying guide for heater core leak sealant to find what you’re looking for:

Brand

In some cases, the brand of heater core leak sealant is very important. For example, if you’re looking for an item that works in tandem with another, you might very well need both products to be the same brand. If this is the case, it’s vital to pay attention to this factor, as choosing the wrong product can mean the difference between wasting your money and buying a great product that functions as it should.

Features

The features in any given heater core leak sealant are important because they can dictate which version of an item you need and how much money you need to spend. Consider all the key features that you want your item to have and don’t settle for anything that doesn’t check at least ¾ of your boxes.

Reviews

Customer reviews about heater core leak sealant are crucial – especially when you’re buying a product that costs a lot of money or serves a big importance. Luckily, most products can be found online, which means that it’s common for there to be scores of customer reviews from those who have already purchased any given product.

Pay attention to these reviews. Take note of the pros and cons that they mention, and factor these into your big decision. In some cases, you’ll be forced to sacrifice one con in order to gain a particular pro, but being aware of the potential con is going to be beneficial in either case.

Quality

Of course, quality is key. You don’t want to purchase a low-quality product. If you do, you run the risk of your item breaking, not working properly, or otherwise proving to be very disappointing, as well as a waste of money.

You can compare heater core leak sealant quality by researching what your potential purchases are made from, contrasting the individual items against each other to discern which one is made of the best materials.

Warranty

Warranty isn’t always going to be important, but it definitely can be. This is especially true if the item in question is tech-related or expensive. A good warranty will be valid for an extended time after purchase and cover a variety of problems ranging from item defects to random accidents, water damage, and other miscellaneous events that could ruin your product.

Conclusion

The quest to find the best heater core leak sealant can be daunting – but it doesn’t have to be. It can be made much easier by asking yourself a few simple questions and then thinking critically about the items you want to buy. Consider their features, quality, brand, warranty, and customer reviews and you’re more likely to make a great purchase.