Top 10 Coolant Stop Leaks
for June 2021

Recommendations are independently chosen by MOOZ’s editors. Purchases you make through our links may earn us a commission.

1
9.7
SCORE
BlueDevil 00211 Coolant Stop Leak - 16 Ounce

BlueDevil Products BlueDevil 00211 Coolant Stop Leak

16 Ounce

by BlueDevil Products
What We like

Easy to use No flushing required

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Product Features

  • Permanent repair for all cooling system leaks
  • Safe for all cooling system components
  • Safely mixes with all types of antifreeze/coolant

Safe for all cooling system components Safely mixes with all types of antifreeze/coolant Permanent repair for all cooling system leaks

2
9.7
SCORE
ATP AT-205 Re-Seal Stops Leaks, 8 Ounce Bottle

ATP Automotive ATP AT-205 Re-Seal Stops Leaks

8 Ounce Bottle

by ATP
What We like

Professional strength fast acting resealer, stops leaks fast

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Product Features

  • 8oz bottle will treat a 6 quart capacity, adjust accordingly
  • Compatible with conventional and synthetic oils, ATF, gear oil, power steering fluids and hydraulic oil
  • Rejuivinates all rubber seals & gaskets in engines, transmissions, power steering, differentials and hydraulic systems
  • Does not contain petroleum distillates, will not over-swell or breakdown seals

Compatible with conventional and synthetic oils, atf, gear oil, power steering fluids and hydraulic oil Rejuivinates all rubber seals & gaskets in engines, transmissions, power steering, differentials and hydraulic systems Does not contain petroleum distillates, will not over-swell or breakdown seals 8oz bottle will treat a 6 quart capacity, adjust accordingly

3
9.5
SCORE
Bar's Leaks 1186 Liquid Aluminum Stop Leak - 16.9 oz

Bar's Leaks 1186 Liquid Aluminum Stop Leak

16.9 oz

by Bar's Leaks
What We like

Special Shipping Information: This item cannot be returned and has additional shipping restrictions

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Product Features

  • Bar's Leaks Liquid Aluminum Stop Leak seals radiator leaks. Seals freeze plug leaks. Repairs gasket leaks and heater core leaks. Lowers water temperature.
  • Repairs gasket leaks
  • Seals freeze plug leaks
  • Seals radiator leaks

Seals radiator leaks Bar's Leaks liquid aluminum stop leak seals radiator leaks. seals freeze plug leaks. repairs gasket leaks and heater core leaks. lowers water temperature. Repairs gasket leaks Seals freeze plug leaks

4
9.1
SCORE
K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak Repair

K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak Repair

by K-Seal
What We like

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

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Product Features

  • No draining or flushing
  • Fixes cracks and leaks in radiator, head gasket, freeze plugs, cylinder heads, heater core, water pump casing and engine blocks
  • Mixes with all antifreeze
  • Permanent coolant leak repair - Just shake, pour and go

Fixes cracks and leaks in radiator, head gasket, freeze plugs, cylinder heads, heater core, water pump casing and engine blocks Permanent coolant leak repair - just shake, pour and go Mixes with all antifreeze No draining or flushing

5
8.9
SCORE
Prestone AS145 Radiator Sealer Stop Leak - 11 oz.

Prestone AS145 Radiator Sealer Stop Leak

11 oz.

by Prestone
What We like

Combination of natural and synthetic components provides the ability to seal leaks up to 0.020" x 0.5"

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Product Features

  • Patented formula quickly stops leaks in radiators, water pumps, and heater cores
  • 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
  • Boosts corrosion inhibitors to protect against pitting and corrosion, which cause radiator leaks

Seals even large leaks without interfering with the flow through the radiator or heater core 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 Stops the leak as well as the corrosive condition that causes it

6
8.9
SCORE
Bar's Leaks 1109 Block Seal Liquid Copper Intake and Radiator Stop Leak - 18 oz.

Bar's Leaks 1109 Block Seal Liquid Copper Intake and Radiator Stop Leak

18 oz.

by Bar's Leaks
What We like

Repairs blocks

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Product Features

  • Repairs freeze plug leaks
  • Repairs blown head gaskets
  • Seals larger leaks seals
  • Repairs heater core leaks

Repairs heater core leaks Repairs freeze plug leaks Repairs blown head gaskets Seals larger leaks seals

7
8.9
SCORE
Liqui Moly 20132 Radiator Stop Leak, 0.25 l, 1 Pack

Liqui Moly 20132 Radiator Stop Leak

0.25 l, 1 Pack

by Liqui Moly
What We like

For all cooling water and heating systems with and without water filters

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Product Features

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

Liqui Moly radiator stop-leak completely seals such leaks immediately with ease. Secures the combustion chamber from damages caused by coolant admission

8
8.6
SCORE
K-Seal Coolant Leak Repair ST5516 Heavy Duty 16oz, Multi-Purpose Formula for Truck/Tractor Coolant Leaks in The Radiator, Head Gasket, Water Pump Casing & Heater Core, A True Pour & Go -Trade Trusted

K-Seal Coolant Leak Repair ST5516 Heavy Duty 16oz

Multi-Purpose Formula for Truck/Tractor Coolant Leaks in The Radiator, Head Gasket, Water Pump Casing & Heater Core, A True Pour & Go -Trade Trusted

by K-Seal
What We like

SCIENTIFICALLY TESTED: Safe and effective, our Heavy Duty Coolant stop leak repair seals leaks up to 1/32 of an inch! Once cured, it withstands the high pressure of the combustion chamber, without failing or clogging the cooling system. US Bestseller

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Product Features

  • REPAIRS IN MINUTES: Create a permanent weld within the entire coolant system, including on hard plastic radiators and aluminum heads and blocks in larger capacity engines, AG, RV etc. The only industrial coolant sealant university tested to meet ASTM D3147.
  • POUR AND GO: Our cooling system sealer is easy to use just shake the bottle, add to your radiator/overflow and run the engine! Unlike some competitive products, it mixes with all types of antifreeze, no draining, flushing or pulling the thermostat required.
  • SEALS CRACKS AND STOPS LEAKS: Avoid expensive downtime, our coolant stop leak will permanently seal cracks and holes! Quickly repair your head gasket, block, leaking radiator, freeze plug, heater core & water pump casing with no adverse impact on efficiency.
  • CUSTOMER SUPPORT: If our engine coolant leak doesnt seal your head gasket, the system might be over-pressurized. Check the Technical Specification section of this page for extra instructions for a successful repair. Over 8 million bottles sold. Save time/money

Seals cracks and stops leaks: avoid expensive downtime, our coolant stop leak will permanently seal cracks and holes! quickly repair your head gasket, block, leaking radiator, freeze plug, heater core & water pump casing with no adverse impact on efficiency. Customer support: if our engine coolant leak doesnt seal your head gasket, the system might be over-pressurized. check the technical specification section of this page for extra instructions for a successful repair. over 8 million bottles sold. save time/money Repairs in minutes: create a permanent weld within the entire coolant system, including on hard plastic radiators and aluminum heads and blocks in larger capacity engines, ag, rv etc. the only industrial coolant sealant university tested to meet astm d3147. Pour and go: our cooling system sealer is easy to use just shake the bottle, add to your radiator/overflow and run the engine! unlike some competitive products, it mixes with all types of antifreeze, no draining, flushing or pulling the thermostat required.

9
8.5
SCORE
J-B Weld DS-114 PERM-O-Seal Radiator Stop Leak - 0.7 oz.

J-B Weld DS-114 PERM-O-Seal Radiator Stop Leak

0.7 oz.

by J-B WELD
What We like

DURABLE FAST FIX: The special compound will quickly seal leaks and will also act as a rust inhibitor and lubricant to internal cooling system parts. It will not clog or harm your cooling system.

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Product Features

  • WHAT THE PROS USE: Mechanics, repair pros, and any avid DIYer knows our products bond strong to a variety of surfaces in even the toughest environments; and they have always been made in the USA.
  • JB WELD PERM O SEAL : Is a specially formulated non-toxic compound ground to a very fine particle size to quickly mix and flow into all areas of the cooling system to find and seal leaks.
  • DO IT YOURSELF: Big or small, you can DIY it with J-B. Our heavy duty adhesives repair & restore it right the first time. JB Weld delivers the legendary performance of the World's Strongest Bond.
  • MONEY SAVING REPAIR SOLUTION: The powered concentrate allows for an economical repair as compared to liquid based alternatives that use similar technology.

Jb weld perm o seal : is a specially formulated non-toxic compound ground to a very fine particle size to quickly mix and flow into all areas of the cooling system to find and seal leaks. What the pros use: mechanics, repair pros, and any avid diyer knows our products bond strong to a variety of surfaces in even the toughest environments; and they have always been made in the usa. Money saving repair solution: the powered concentrate allows for an economical repair as compared to liquid based alternatives that use similar technology. Do it yourself: big or small, you can diy it with j-b. our heavy duty adhesives repair & restore it right the first time. jb weld delivers the legendary performance of the world's strongest bond.

10
7.9
SCORE
Bar's Leaks 1194 Radiator Stop Leak Concentrate - 6 oz.

Bar's Leaks 1194 Radiator Stop Leak Concentrate

6 oz.

by Bar's Leaks
What We like

package weight :0.81lbs

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Product Features

  • country of origin :United States
  • Product type :AUTO ACCESSORY
  • Package dimensions :4.064 cm L x6.096 cm W x12.446 cm H

Package dimensions :4.064 cm l x6.096 cm w x12.446 cm h Product type :auto accessory Country of origin :united states

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