Radiator Sealant Permatex Radiator Sealant 400 mL, bottle

Permatex Radiator Sealant 400 mL is a ready-to-use liquid formulated to seal small leaks, pinholes and hairline cracks in radiators, heater cores and hoses. Supplied in a compact bottle for convenient handling, it is intended for rapid, temporary repair of coolant system leaks to reduce coolant loss and lower the risk of engine overheating. The formulation circulates with the cooling system to locate and seal the leakage points without disassembly of cooling system components.

Advantages

This radiator sealant offers quick application from a single bottle and works with existing coolant to form a durable seal at small leak sites. It is suitable for use in passenger cars and light vehicles and does not require flushing or special tools for initial application. The product is formulated to circulate with the cooling fluid, enabling sealing of leaks in radiators, heater cores and flexible hoses without immediate component removal.

Suitable for

• Temporary repair of small radiator and heater core leaks
• Sealing pinholes and hairline cracks in coolant hoses
• Emergency roadside coolant loss reduction
• Short-term prevention of engine overheating due to minor coolant leaks

Key specifications

• Form: ready-to-use liquid in a 400 mL bottle
• Compatibility: designed to work with standard engine coolant/antifreeze
• Application: internal circulation with the cooling system
• Intended vehicle types: passenger cars and light vehicles
• Primary function: seals small leaks, pinholes and hairline cracks

How to use

Ensure the engine is cool before opening the cooling system. Shake the bottle and add the recommended amount of sealant directly into the radiator filler neck or coolant reservoir, following the dosing instructions provided by the manufacturer. Start the engine and allow the cooling system to circulate the sealant; run the engine until normal operating temperature is reached so the product can travel to the leak site and form a seal. Monitor coolant level and temperature after application and top up coolant if required.

Usage recommendations

Use for temporary or emergency repairs only. After applying the sealant, inspect the cooling system and, where practical, arrange a permanent repair or component replacement as soon as possible. Do not use in systems with severe long cracks or large holes; avoid overfilling and follow vehicle manufacturer coolant recommendations. Store the bottle in a cool, dry place away from direct heat sources and keep out of reach of children.