The Best Heater Core Leak Sealant of 2023

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.

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.

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

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

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

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

Seals leaks

Conditions cooling system

Inhibits rust and corrosion

Lubricates water pump seals

Helps control electrolysis

Non-toxic

DEX-COOL compatible

Engine application is based on liters of volume in cooling system

Formulated for automotive use

For use with all vehicles

Seals larger leaks seals

Repairs heater core leaks

Repairs freeze plug leaks

Repairs blown head gaskets

Repairs blocks

Works with all types and colors of anti-freeze coolant

Stops and seals coolant leaks

One bottle treats up to 4 gallons

Works with all types and colors of anti-freeze coolant

Stops and seals coolant leaks

One bottle treats up to 4 gallons