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Radiator Stop Leak Powder


Stops Leaks up to 0.9 mm
Will not Clog the Cooling System

Bar's Leaks Radiator Stop Leak is an easy to carry product for emergency cooling system leak repair.  Formulated to seal minor leaks up to 0.9mm in the cooling system. Bar’s Leaks works on plastic, aluminum, and metal radiators in heater cores, engine cooling jacket, gaskets (including head gaskets), and freeze plugs.  

Keep Bar's Leaks Radiator Stop Leak Powder ready in your emergency kit or glove box.

  • Stops internal and external leaks up to 0.9 mm in size

  • Will not clog cooling system

Product Code: RHZ1M20 
Bottle Sizes: Net 25g


Safety Data Sheets (SDS)
Technical Data Sheets (TDS)

How does Bar's Leaks Radiator Stop Leak work?

When reaching an external leak, it travels between the holes, gaps, and cracks and collects around the outer perimeter of the leak.  Then builds inward, effectively sealing the leak. When exposed to air, it expands up to 15% in size, creating a tight seal capable of holding in pressures exceeding the maximum designed for cooling systems.  Resulting in a strong seal without clogging your cooling system.

Bar's Leaks Radiator Stop Leak is best installed directly into the radiator or through the upper radiator hose.  If no access direct access is available, install in the coolant reservoir and allow more time for the product to circulate within the cooling system.

Run/idle the engine for 15 min.

We recommend to drive/idle for 15 to 30 minutes.  If the cooling system leak persists, a second dose may be required or the leak is too large and mechanical repair is needed.

4-6 cylinder engines: use 1 25g bottle. 
8 cylinder engines: use 2x 25g bottle.
> 8 cylinder engines: use 1 25g bottle for every 2 gallons.

The cooling system must be clean and free of other types of stop leak products. If it is necessary to remove other anti-leakage substances, or if the engine is over 2 years old or has traveled over 25,000 miles,, clean the system with Bar's Nural before using Bar's Leaks Radiator Stop Leak.