Radiator Stop-Leak

Small leaks caused by stone impacts, porous soldering points and hairline cracks in the cooling simple are easy to localize (one notices that the cooling water level is sinking). LIQUI MOLY Radiator Stop-Leak completely seals such leaks immediately with ease. Secures the combustion chamber from damages caused by coolant admission.

Available pack sizes

250 ml Can sheet metal (Part No. 8370)
150 ml Can sheet metal (Part No. 8371)

Technical Data Sheet


Radiator Stop-Leak is a dispersion for sealing leaks in water-cooling systems in motor vehicles. The product reliably seals hair cracks and small leaks. The solids dispersion is stabilized in carrier fluid.

Intended use

For all cooling water and heating systems with and without water filters. Also suitable for aluminum and plastic radiators. The contents is sufficient for 10 liters of coolant. Compatible with all standard treating agents for coolants and antifreeze. Can also be used as a preventative measure.


  • compatible with conventional coolant water refiners and antifreezes
  • 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

Areas of application

Used for sealing small leaks in cooling circuits of passenger motor vehicles, commercial vehicles, buses and two-wheel vehicles. Also suitable for cooling circuit with filters.


Shake container before use. Run the heating system. With the engine running, pour the contents into the cooling fluid at operating temperature and allow the engine to continue running for a further 10 minutes. The contents is sufficient for 10 liters of coolant.