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20 Best Heater Core Stop Leak (2023 Updated)

Heater core stop leak is a sealant that can be used to repair minor leaks in the heater core. This sealant will not only stop the leak, but will also prevent any further damage to the heater core.

20 Best Heater Core Stop Leak

Product Image Product Name Features Price

Bar's Leaks – 11 oz. Radiator Stop Leak

  • Works with any color antifreeze
  • Stops leaks and drips from wear and age
  • Harmless to rubber, aluminum & other metals

Bar's Leaks Liquid Aluminum Radiator Stop Leak 16.9oz

  • Safely Seals Leaks
  • Stops Overheating
  • Reduces Water Temperature

Bar's Leaks Pelletized Radiator Stop Leak 11oz

  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion

Bar's Leaks – 18oz. Block Seal Liquid Copper Intake & Radiator Stop

  • One Step, No Draining Required
  • Antifreeze Compatible Sodium Silicate Formula
  • Permanent Cooling System Repair

Liqui Moly 20132 – Radiator Stop Leak

  • LIQUI MOLY Radiator Stop-Leak completely seals such leaks immediately with ease.
  • Secures the combustion chamber from damages caused by coolant admission.

Bar's Leaks Radiator Stop Leak Tablets

  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion

K Seal Heavy Duty Permanent Coolant Leak Sealer – 16 oz jug

  • Item Weight 544 g
  • Product Dimensions 15 x 10.4 x 4.8 cm
  • Item Weight 544 gm

K-Seal Coolant Leak Repair, Head Gasket Sealant, Block Sealer, Radiator, Heater Core Stop Leak, ST5501

  • Advanced ceramic forumla Product Features: Anyone can use this product.
  • No Flushing or Draining.
  • You can even pour into the overflow tank. Mixes w/all types of antifreeze Just shake, pour & go.

Wynns WY55864 Radiator Stop Leak 325ml

  • Stops and prevents leaks in the radiator and cooling
  • Stops and prevents leaks
  • Stops head gasket leaks

AlumaSeal ASBPI12 Radiator Stop Leak Powder Blister Card – 20 G

  • Inhibits rust
  • Lubricates water pump
  • Quick permanent seal

K-Seal ST5501 Permanent Coolant Leak Repair – 8 oz bottle

  • No Flushing. Just shake, pour and go!
  • Mixes with all types of Antifreeze.
  • Multi Purpose ONe Step & Permanent.

Oatey Hercules Reddish Brown Boiler Liquid Stop Leak – 1 qt bottle

  • The product is easy to use
  • The product is highly durable and handle
  • The product is manufactured in China

Bar's Leaks Cooling System Repair – 16.9 fl oz bottle

  • Scientifically Formulated To Stop Coolant Leaks, Thereby Reducing Antifreeze Loss
  • Cooling System Repair Stops Overheating And Reduces Water Temperature

Atomex Stop Leak Radiator Cooling System Additive

  • Latest generation product designed to eliminate leaks in the cooling system.
  • Tightens loose gaskets of the cylinder block, etc.

Rislone Block Seal Stop Leak

  • 1 Step Sealer
  • Antifreeze Compatible
  • Permanently Repairs Larger Leaks

Permatex 80884 GAS Tank and Radiator Repair

  • Gas tank and radiator repair
  • Seals small holes and weak seams in gas tank without welding or tank removal
  • Repairs leaks and holes in all types of radiators

CRC – 401214×6 – K&W Instant Cooling System Stop Lea

  • ItemNumber#C28401214X6
  • Using Nanotechnology, This Product Fills In Cracks And Crevices Other Products Can’t, Making A Stronger, More Solid Bond Than Competitors’ Products

Hi-Gear HG9048s Insta-Seal Permanent Block Sealer – 8 fl. oz.

  • Hi-Gear HG9048s Insta-Seal Permanent Block Sealer – 236 millilitres
  • Hi-Gear Insta-Seal quickly and permanently seals large and small leaks in blown head gaskets

Wynn's 1831004 45641 Cooling System Stop Leak 325 ml

  • Value for money
  • Safely packed
  • High quality
Bar's Leaks – 11 oz. Radiator Stop Leak
  • Works with any color antifreeze
  • Stops leaks and drips from wear and age
  • Harmless to rubber, aluminum & other metals
Bar's Leaks Liquid Aluminum Radiator Stop Leak 16.9oz
  • Safely Seals Leaks
  • Stops Overheating
  • Reduces Water Temperature
Bar's Leaks Pelletized Radiator Stop Leak 11oz
  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion
Bar's Leaks – 18oz. Block Seal Liquid Copper Intake & Radiator Stop
  • One Step, No Draining Required
  • Antifreeze Compatible Sodium Silicate Formula
  • Permanent Cooling System Repair
Liqui Moly 20132 – Radiator Stop Leak
  • LIQUI MOLY Radiator Stop-Leak completely seals such leaks immediately with ease.
  • Secures the combustion chamber from damages caused by coolant admission.
Bar's Leaks Radiator Stop Leak Tablets
  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion
K Seal Heavy Duty Permanent Coolant Leak Sealer – 16 oz jug
  • Item Weight 544 g
  • Product Dimensions 15 x 10.4 x 4.8 cm
  • Item Weight 544 gm
K-Seal Coolant Leak Repair, Head Gasket Sealant, Block Sealer, Radiator, Heater Core Stop Leak, ST5501
  • Advanced ceramic forumla Product Features: Anyone can use this product.
  • No Flushing or Draining.
  • You can even pour into the overflow tank. Mixes w/all types of antifreeze Just shake, pour & go.
Wynns WY55864 Radiator Stop Leak 325ml
  • Stops and prevents leaks in the radiator and cooling
  • Stops and prevents leaks
  • Stops head gasket leaks
AlumaSeal ASBPI12 Radiator Stop Leak Powder Blister Card – 20 G
  • Inhibits rust
  • Lubricates water pump
  • Quick permanent seal
K-Seal ST5501 Permanent Coolant Leak Repair – 8 oz bottle
  • No Flushing. Just shake, pour and go!
  • Mixes with all types of Antifreeze.
  • Multi Purpose ONe Step & Permanent.
Oatey Hercules Reddish Brown Boiler Liquid Stop Leak – 1 qt bottle
  • The product is easy to use
  • The product is highly durable and handle
  • The product is manufactured in China
Bar's Leaks Cooling System Repair – 16.9 fl oz bottle
  • Scientifically Formulated To Stop Coolant Leaks, Thereby Reducing Antifreeze Loss
  • Cooling System Repair Stops Overheating And Reduces Water Temperature
Atomex Stop Leak Radiator Cooling System Additive
  • Latest generation product designed to eliminate leaks in the cooling system.
  • Tightens loose gaskets of the cylinder block, etc.
Rislone Block Seal Stop Leak
  • 1 Step Sealer
  • Antifreeze Compatible
  • Permanently Repairs Larger Leaks
Permatex 80884 GAS Tank and Radiator Repair
  • Gas tank and radiator repair
  • Seals small holes and weak seams in gas tank without welding or tank removal
  • Repairs leaks and holes in all types of radiators
CRC – 401214×6 – K&W Instant Cooling System Stop Lea
  • ItemNumber#C28401214X6
  • Using Nanotechnology, This Product Fills In Cracks And Crevices Other Products Can’t, Making A Stronger, More Solid Bond Than Competitors’ Products
Hi-Gear HG9048s Insta-Seal Permanent Block Sealer – 8 fl. oz.
  • Hi-Gear HG9048s Insta-Seal Permanent Block Sealer – 236 millilitres
  • Hi-Gear Insta-Seal quickly and permanently seals large and small leaks in blown head gaskets
Wynn's 1831004 45641 Cooling System Stop Leak 325 ml
  • Value for money
  • Safely packed
  • High quality

1. Bar’s Leaks – 11 oz. Radiator Stop Leak

Bar's Leaks - 11 oz. Radiator Stop Leak

  • Works with any color antifreeze
  • Stops leaks and drips from wear and age
  • Harmless to rubber, aluminum & other metals

Check Latest Price

Sold By Price
Amazon.com – Seller
Walmart
AutoZone
Ace Hardware

Product Details

Specifications

Details
Product Type Stop Leak Concentrate
Container Size 11 oz
Brand Name Bar’s Leaks

Reviews From Real Customers

Kurt P
oguz1
foster

2. Bar’s Leaks Liquid Aluminum Radiator Stop Leak 16.9oz

Bar's Leaks Liquid Aluminum Radiator Stop Leak 16.9oz

  • Safely Seals Leaks
  • Stops Overheating
  • Reduces Water Temperature

Check Latest Price

Sold By Price
Amazon.com
Walmart
AutoZone
Ace Hardware

Product Details

Specifications

Details
Excluded Ship States No
Item has MSDS (SDS)? Y
Special Instructions Use 1/2 (half) bottle in a small cooling system, such as 4 cylinders with no A/C. Use 1 (one) bottle for regular size systems, most 4, 6, 8 and 10 cylinder engines.
Item is Shipped at this Packaging Level N
Information Effective Date 2011-06-27 12:00:00

Reviews From Real Customers

Precioso
Joey
Watterson

3. Bar’s Leaks Pelletized Radiator Stop Leak 11oz

Bar's Leaks Pelletized Radiator Stop Leak 11oz

  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion
  • Lubricates water pump seals
  • Helps control electrolysis

Check Latest Price

Sold By Price
Amazon.com
eBay
Walmart
AutoZone

Product Details

Specifications

Details
Item has MSDS (SDS)? Y
Special Instructions Use 1 bottle for 6, 8 and 10 cylinder gas or diesel engines. For 4 cylinder engines, use 1/2 of liquid and pellets. One bottle treats systems up to 4 gallons.
Package Weight 11
Package Weight UOM OZ
Package Size 11 oz

Reviews From Real Customers

Kimberly
Guy
2015-steif

4. Bar’s Leaks – 18oz. Block Seal Liquid Copper Intake & Radiator Stop

Bar's Leaks - 18oz. Block Seal Liquid Copper Intake & Radiator Stop

  • One Step, No Draining Required
  • Antifreeze Compatible Sodium Silicate Formula
  • Permanent Cooling System Repair
  • Works With All Types Of Antifreeze Or Water

Check Latest Price

Sold By Price
Amazon.com
eBay
Walmart
AutoZone

Product Details

Specifications

Details
Item has MSDS (SDS)? Y
Special Instructions Use 1/2 (half) bottle in a small cooling systems, such as 4 cylinders with no A/C. Use 1 (one) bottle for regular size systems, which are most 4, 6, 8 and 10 cylinder engines. For larger systems, use 1 bottle for every 6 gallons of cooling system capacity.
Package Weight 18
Package Weight UOM OZ
Package Size 18 oz

Reviews From Real Customers

JP [Crazytekkie] (Crazytekkie)
Frustrated
Ryan

5. Liqui Moly 20132 – Radiator Stop Leak

Liqui Moly 20132 - Radiator Stop Leak

  • LIQUI MOLY Radiator Stop-Leak completely seals such leaks immediately with ease.
  • Secures the combustion chamber from damages caused by coolant admission.
  • For all cooling water and heating systems with and without water filters.

Check Latest Price

Sold By Price
Amazon.com – Seller
ECS Tuning
FCP Euro
Turner Motorsport

Product Details

Specifications

Details
Length 6.5 in
Height 2.5 in
Width 2.5 in
Weight 0.7 lb

Reviews From Real Customers

Br3adpan
fcpeuro.com
finglonga

6. Bar’s Leaks Radiator Stop Leak Tablets

Bar's Leaks Radiator Stop Leak Tablets

  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion
  • Lubricates water pump seals
  • Helps control electrolysis

Check Latest Price

Sold By Price
Amazon.com – Seller
eBay
NAPA Auto Parts
Advance Auto Parts

Product Details

Reviews From Real Customers

Glenn
Mark W.
TahoeJoe

7. K Seal Heavy Duty Permanent Coolant Leak Sealer – 16 oz jug

K Seal Heavy Duty Permanent Coolant Leak Sealer - 16 oz jug

  • Item Weight 544 g
  • Product Dimensions 15 x 10.4 x 4.8 cm
  • Item Weight 544 gm

Check Latest Price

Sold By Price
Amazon.com
eBay
Walmart
JBTools.com

Product Details

Specifications

Details
Product Dimensions 5.9 x 4.1 x 1.9 inches
Country of Origin USA
Is Discontinued By Manufacturer No

Reviews From Real Customers

H.G.R.
D.B.P.
K.

8. K-Seal Coolant Leak Repair, Head Gasket Sealant, Block Sealer, Radiator, Heater Core Stop Leak, ST5501

K-Seal Coolant Leak Repair, Head Gasket Sealant, Block Sealer, Radiator, Heater Core Stop Leak, ST5501

  • Advanced ceramic forumla Product Features: Anyone can use this product.
  • No Flushing or Draining.
  • You can even pour into the overflow tank. Mixes w/all types of antifreeze Just shake, pour & go.
  • Works in just minutes Works on Head Gaskets, Radiator, Heater Cores, Freeze Plugs, Water Pump Casings, Cylinder Heads & Cracked Blocks.

Check Latest Price

Sold By Price
Amazon
eBay
Walmart
NAPA Auto Parts

Product Details

Reviews From Real Customers

Drew
Martin
C.J.

9. Wynns WY55864 Radiator Stop Leak 325ml

Wynns WY55864 Radiator Stop Leak 325ml

  • Stops and prevents leaks in the radiator and cooling
  • Stops and prevents leaks
  • Stops head gasket leaks
  • Protects the cooling system
  • Anti-corrosion

Check Latest Price

Sold By Price
Amazon
eBay
Bonanza – roxy media’s booth
NxDeals.com

Product Details

Specifications

Details
Product Genre/Category Auto

Reviews From Real Customers

GSI SID
Lee337
Garjay

10. AlumaSeal ASBPI12 Radiator Stop Leak Powder Blister Card – 20 G

AlumaSeal ASBPI12 Radiator Stop Leak Powder Blister Card - 20 G

  • Inhibits rust
  • Lubricates water pump
  • Quick permanent seal
  • Compatible w/all antifreeze including extended life coolants
  • Will not clog cooling systems

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Sold By Price
Amazon
Ace Hardware
Advance Auto Parts
Long Beach Ace Hardware

Product Details

Specifications

Details
Recommended Surface Type Aluminum
Container Size 0.7 oz
Brand Name AlumAseal
Product Type Stop Leak Radiator Sealer

Reviews From Real Customers

Pablo
Advance Auto Parts
Nodrog

11. K-Seal ST5501 Permanent Coolant Leak Repair – 8 oz bottle

K-Seal ST5501 Permanent Coolant Leak Repair - 8 oz bottle

  • No Flushing. Just shake, pour and go!
  • Mixes with all types of Antifreeze.
  • Multi Purpose ONe Step & Permanent.

Check Latest Price

Sold By Price
Amazon
eBay
Agri Supply
ToolTopia.com

Product Details

Specifications

Details
Units in Package 1
Unit Size 8 oz

Reviews From Real Customers

Sirstylish
Tim

12. Oatey Hercules Reddish Brown Boiler Liquid Stop Leak – 1 qt bottle

Oatey Hercules Reddish Brown Boiler Liquid Stop Leak - 1 qt bottle

  • The product is easy to use
  • The product is highly durable and handle
  • The product is manufactured in China
  • Seals and repairs cracks and leaks in steam and hot water systems
  • No odors, no priming, no foaming

Check Latest Price

Sold By Price
Amazon
Walmart
SupplyHouse.com
Valu Home Centers

Product Details

Reviews From Real Customers

WildFire
loops
Mickey

13. Bar’s Leaks Cooling System Repair – 16.9 fl oz bottle

Bar's Leaks Cooling System Repair - 16.9 fl oz bottle

  • Scientifically Formulated To Stop Coolant Leaks, Thereby Reducing Antifreeze Loss
  • Cooling System Repair Stops Overheating And Reduces Water Temperature
  • Works With Any Color Antifreeze
  • Reinforced With Carbon Fiber

Check Latest Price

Sold By Price
Amazon
Walmart
AutoZone
NAPA Auto Parts

Product Details

Specifications

Details
Size 1 Pack

Reviews From Real Customers

Snobordnut
Nikkolas
TonyaMac

14. Atomex Stop Leak Radiator Cooling System Additive

Atomex Stop Leak Radiator Cooling System Additive

  • Latest generation product designed to eliminate leaks in the cooling system.
  • Tightens loose gaskets of the cylinder block, etc.
  • Completely eliminates leaks, reliably and permanently seals cracks and minor (up to 0.9 mm) damages in pipelines and joints.
  • Protects the cooling system from rust and corrosion for a long period.
  • Universal in application for gasoline and diesel engines of cars and other equipment.

Check Latest Price

Sold By Price
Amazon
eBay
Walmart – Xado Tech LLC
XADO

Product Details

Reviews From Real Customers

menakajd
plasterer0170
xado-france.com

15. Rislone Block Seal Stop Leak

Rislone Block Seal Stop Leak

  • 1 Step Sealer
  • Antifreeze Compatible
  • Permanently Repairs Larger Leaks
  • Compatible Will All Types of 50/50 Mix Antifreeze
  • Made in the USA

Check Latest Price

Sold By Price
Amazon
eBay
bigamart.com

Product Details

Specifications

Details
dimensions 16.77 x 16.77 x 47.74 cm; 559.99 Grams

Reviews From Real Customers

LetsGo
Jack2011
Jody

16. Permatex 80884 GAS Tank and Radiator Repair

Permatex 80884 GAS Tank and Radiator Repair

  • Gas tank and radiator repair
  • Seals small holes and weak seams in gas tank without welding or tank removal
  • Repairs leaks and holes in all types of radiators
  • Hardens in 60 seconds
  • For use on these suggested applications: holes and seams in gas tank, radiator or gas can

Check Latest Price

Sold By Price
Amazon
eBay – finditparts
Autoplicity.com

Product Details

Specifications

Details
Units in Package 1
Unit Size 1 oz stick

Reviews From Real Customers

DeeMan8
Spencer
Member 1215583089

17. CRC – 401214×6 – K&W Instant Cooling System Stop Lea

CRC - 401214x6 - K&W Instant Cooling System Stop Lea

  • ItemNumber#C28401214X6
  • Using Nanotechnology, This Product Fills In Cracks And Crevices Other Products Can’t, Making A Stronger, More Solid Bond Than Competitors’ Products
  • Compatible With All Types Of Anti-Freeze

Check Latest Price

Sold By Price
Amazon
eBay
Walmart
AutoZone

Product Details

Specifications

Details
Appearance Lumpy Copper Liquid
Odor Mild
Container Size 15 fl oz (US)
Acts as Stop Leak No
SDS Required Yes

Reviews From Real Customers

Autologous1
Cuso
Rodger76

18. AlumaSeal Radiator Stop Leak and Conditioner Liquid (16 fl. oz.)

AlumaSeal Radiator Stop Leak and Conditioner Liquid (16 fl. oz.)

Check Latest Price

Sold By Price
Amazon
eBay – mysaver

Product Details

Reviews From Real Customers

Ed
gianna
Shaggy

19. Hi-Gear HG9048s Insta-Seal Permanent Block Sealer – 8 fl. oz.

Hi-Gear HG9048s Insta-Seal Permanent Block Sealer - 8 fl. oz.

  • Hi-Gear HG9048s Insta-Seal Permanent Block Sealer – 236 millilitres
  • Hi-Gear Insta-Seal quickly and permanently seals large and small leaks in blown head gaskets
  • Works on cracked cylinder heads, heater matrix, core plugs and leaking radiators in all types of aluminum and cast iron engines
  • Hi-Gear Insta-Seal will not harm the cooling system when used correctly
  • Once the ‘weld’ is complete Hi-Gear Insta-Seal lasts the life of the engine

Check Latest Price

Sold By Price
Amazon
eBay
MechanicSurplus.com

Product Details

Reviews From Real Customers

ranger7968
dynodougmb
nd-farmer

20. Wynn’s 1831004 45641 Cooling System Stop Leak 325 ml

Wynn's 1831004 45641 Cooling System Stop Leak 325 ml

  • Value for money
  • Safely packed
  • High quality
  • Range always up-to-date

Check Latest Price

Sold By Price
Amazon
eBay – mongrossisteauto

Product Details

Reviews From Real Customers

mw1043
egon1311
Bronsgeest

Conclusion

There are many different ways to fix a heater core leak, but the most important thing is to make sure that the leak is stopped. Heater core stop leak products are designed to do just that, and they can be a great way to save money on repairs.

However, it is important to remember that these products are not a permanent fix, and they should only be used as a last resort. If you have a heater core leak, the best thing to do is to take your car to a mechanic and have it fixed properly.

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