Hapco Heavy Duty Block Sealer is guaranteed to stop existing block leaks fast! Our formula does not contain metal flakes, is compatible with all types of antifreeze, will not plug the heater core and is safe for all cooling systems. Specially formulated to permanently seal and protect against future leaks. Also safe to use for radiator and head gasket repairs.
- Mixes with all types of antifreeze
- Will not plug heater core
- Safe for plastic and aluminum units
- Makes a permanent seal
- Rust inhibitor