20 Best Stop Leak For Heater Core (2022 Updated)

When you shop through links on our site, we may earn an affiliate commission. This educational content is not intended to be a substitute for professional advice.

In general, stop leak products for heater cores are designed to seal any leaks in the core, thus preventing coolant from leaking out. These products may come in liquid or powder form, and may need to be mixed with water before being applied.

It is important to follow the instructions on the product packaging carefully in order to achieve the best results.

20 Best Stop Leak For Heater Core

Product Image Product Name Features Price

Bar's Leaks Pelletized Radiator Stop Leak 11oz

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

Bar's Leaks Liquid Aluminum Radiator Stop Leak 16.9oz

  • Safely Seals Leaks
  • Stops Overheating
  • Reduces Water Temperature

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 – 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.

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 Permanent Leak Repair for Radiators, Head Gaskets, Blocks

  • 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

Bar's Leaks Radiator Stop Leak Tablets

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

Alumaseal Radiator Stop Leak & Conditioner – 16 fl oz bottle

  • Stops leaks safely, quickly, and easily
  • Compatible with all antifreeze and coolants
  • Safe for all metal, plastic, and rubber cooling system parts

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

Liqui Moly Radiator Stop Leak 250ml

  • suitable for aluminum radiators.
  • permanently and reliably seals hairline cracks and small leaks.
  • no negative side effects on the water pump or heating circuit.

Liquid AlumaSeal Radiator Leak Stop, 16-oz.

  • Radiator Stop Leak Seals Better, Faster. – Stops Leaks Safely, Quickly & Easily. – Compatible With All Antifreeze. – Dimension

Wynn's 1831004 45641 Cooling System Stop Leak 325 ml

  • Value for money
  • Safely packed
  • High quality

Rislone Block Seal Stop Leak

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

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.

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.

AlumaSeal ASBPI12 Radiator Stop Leak Powder Blister Card – 20 G

  • Inhibits rust
  • Lubricates water pump
  • Quick permanent seal
Bar's Leaks Pelletized Radiator Stop Leak 11oz
  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion
Bar's Leaks Liquid Aluminum Radiator Stop Leak 16.9oz
  • Safely Seals Leaks
  • Stops Overheating
  • Reduces Water Temperature
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 – 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.
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 Permanent Leak Repair for Radiators, Head Gaskets, Blocks
  • 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
Bar's Leaks Radiator Stop Leak Tablets
  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion
Alumaseal Radiator Stop Leak & Conditioner – 16 fl oz bottle
  • Stops leaks safely, quickly, and easily
  • Compatible with all antifreeze and coolants
  • Safe for all metal, plastic, and rubber cooling system parts
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
Liqui Moly Radiator Stop Leak 250ml
  • suitable for aluminum radiators.
  • permanently and reliably seals hairline cracks and small leaks.
  • no negative side effects on the water pump or heating circuit.
Liquid AlumaSeal Radiator Leak Stop, 16-oz.
  • Radiator Stop Leak Seals Better, Faster. – Stops Leaks Safely, Quickly & Easily. – Compatible With All Antifreeze. – Dimension
Wynn's 1831004 45641 Cooling System Stop Leak 325 ml
  • Value for money
  • Safely packed
  • High quality
Rislone Block Seal Stop Leak
  • 1 Step Sealer
  • Antifreeze Compatible
  • Permanently Repairs Larger Leaks
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.
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.
AlumaSeal ASBPI12 Radiator Stop Leak Powder Blister Card – 20 G
  • Inhibits rust
  • Lubricates water pump
  • Quick permanent seal

1. 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

2015-steif
JoeCLEAN

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
Watterson

3. 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

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)
Sigmaster

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
finglonga
2trippers

6. 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.

7. K-Seal Permanent Leak Repair for Radiators, Head Gaskets, Blocks

K-Seal Permanent Leak Repair for Radiators, Head Gaskets, Blocks

  • 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
  • Just shake, pour and go

Check Latest Price

Sold By Price
Amazon.com

Product Details

Specifications

Details
Product Dimensions 7.87 x 2 x 6 inches
Country of Origin USA
Is Discontinued By Manufacturer No

Reviews From Real Customers

Chato

8. 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

TahoeJoe

9. Alumaseal Radiator Stop Leak & Conditioner – 16 fl oz bottle

Alumaseal Radiator Stop Leak & Conditioner - 16 fl oz bottle

  • Stops leaks safely, quickly, and easily
  • Compatible with all antifreeze and coolants
  • Safe for all metal, plastic, and rubber cooling system parts
  • Guaranteed to work

Check Latest Price

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

Product Details

Specifications

Details
Item has MSDS (SDS)? Y
Item is Shipped at this Packaging Level Y
Information Effective Date 2/14/2011 12:00:00 AM
Layers Per Pallet 4
Packaging Depth 1.75 IN

Reviews From Real Customers

gianna

10. 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

C.J.
Sirstylish

11. 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

12. Liqui Moly Radiator Stop Leak 250ml

Liqui Moly Radiator Stop Leak 250ml

  • suitable for aluminum radiators.
  • permanently and reliably seals hairline cracks and small leaks.
  • no negative side effects on the water pump or heating circuit.
  • for preventive use For all cooling water and heating systems with and without water filters.

Check Latest Price

Sold By Price
Amazon
MicksGarage.com

Product Details

Reviews From Real Customers

malco-birc

13. Liquid AlumaSeal Radiator Leak Stop, 16-oz.

Liquid AlumaSeal Radiator Leak Stop, 16-oz.

  • Radiator Stop Leak Seals Better, Faster. – Stops Leaks Safely, Quickly & Easily. – Compatible With All Antifreeze. – Dimension
  • 1.56 x 3 x 5.06 in.Item Weight

Check Latest Price

Sold By Price
Amazon
eBay – rugged-parts
Walmart
MechanicSurplus.com

Product Details

Specifications

Details
Case Pack 12
Compatible Transmission Type Automatic and Powershift
Each Weight 1.220 LB

14. 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

15. Bar’s Leaks 1196 Grey Radiator Stop Leak – 11 oz.

Bar's Leaks 1196 Grey Radiator Stop Leak - 11 oz.

Check Latest Price

Sold By Price
Amazon
Walmart – Shop Eddies

Product Details

Specifications

Details
Assembled Product Weight 10 lbs

16. 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

Jack2011

17. 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

18. 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

19. 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

20. 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

Check Latest Price

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

Nodrog
diver1972

Best Stop Leak For Heater Core Buying Guides

Introduction

Heater cores can develop leaks over time. Stop leak can be used to temporarily seal these leaks. It is important to note that stop leak is not a permanent fix and should only be used as a last resort.

The best way to fix a leaking heater core is to replace it.

Symptoms of a Leaking Heater Core

The most common symptom of a leaking heater core is a sweet, antifreeze smell inside the car. Other signs may include steamy windows, low coolant levels, overheating, and engine overheating.

Causes of a Leaking Heater Core

There are many potential causes for a leaking heater core, but the most common one is a coolant leak. Other potential causes could include a clogged or damaged drain line, a faulty radiator cap, or a problem with the water pump.

If you’re not sure what’s causing the leak, it’s best to take your car to a mechanic or a dealership to have it checked out.

How to Fix a Leaking Heater Core

If your car’s heater core is leaking, you can try to fix it with a product called stop leak. Stop leak is a sealant that can sometimes be used to repair leaks in radiators and heater cores. To use stop leak, first, you need to find the source of the leak.

Once you’ve found the leak, clean the area around it with a rag. Then, open the stop leak bottle and pour it into the radiator or heater core. Be sure to follow the directions on the stop leak bottle, as too much stop leak can actually make the leak worse.

If the leak is small, stop leak may be able to seal it. However, if the leak is large, you’ll likely need to replace the radiator or heater core.

Prevention

The best way to prevent stop leak for a heater core is to have the system flushed and refilled with fresh antifreeze on a regular basis. This will help to remove any build-up of corrosion or sediment that could clog the tiny passages in the core.

Additionally, using a quality antifreeze that contains corrosion inhibitors will help to protect the metal surfaces from corrosion.

Resources

There are a few different ways to stop a leak in a heater core. One way is to use a sealant specifically designed for leaks in this type of system. Another way is to replace the heater core entirely.

Conclusion

The conclusion of stop leak for heater core is that it is an effective way to temporarily repair a small leak in the heater core. It is not a permanent fix and should only be used as a last resort.

How useful was this post?

Click on a star to rate it!

Average rating 0 / 5. Vote count: 0

No votes so far! Be the first to rate this post.

Sharing is caring!

Leave a Comment