- Permanent molecular seal that’s as strong as steel.
- Trusted Formula Since 1938.
- Seals cracks & holes in cast iron and aluminum engine blocks, head gaskets, freeze plugs, and copper, aluminum and bi-material radiators & heater cores.
- For use in all water-cooled diesel and gasoline vehicles.
- Withstands extreme pressure and temperatures of a cooling system and will not wash away.
- Professional grade formula exceeds ASTM D6107 for effectively sealing leaks in cooling systems.
- Tested by an independent test lab and rated number one.
- For application to aluminum engine blocks, cooling systems, cylinder heads, engine blocks, freeze plugs, head gaskets, heater cores, iron engine blocks, metal radiators, plastic radiators, radiators, and water pumps.
DIY Skill Level: Medium
Permanent Repair
2 Hours
+ Sit for 24hrs
Est Cost
$9-$12
Est Savings
$800 to $1500
Money Back Guarantee
DIRECTIONS: Read entire label before using this product. DO NOT ADD TO OIL OR ANTIFREEZE. Not following directions EXACTLY could cause severe engine damage.
- With engine cool, remove thermostat (see manufacturer’s specs) and radiator cap. Replace thermostat housing. Set heater control to maximum hot position.
- Idle engine until warm.
- Stop engine and drain radiator. DISPOSAL: Observe local laws & regulations. DO NOT pour on ground or in storm drain.
- Close drain and refill radiator with water. Idle for 5 minutes to flush excess antifreeze from system. Turn off engine and drain cooling system. Repeat until water runs clear. For best results, flush cooling system with K&W® Cooling System Flush #401320.
- Shake can and mix with 3 quarts of hot water in a separate container. Small engines may require less than 3 quarts of hot water mixture. (Tip: Use a 1-gallon milk or water jug.) Note: If coolant is leaking into a cylinder remove and check spark plugs for an orange/white crystal or fluid appearance. Remove the affected spark plug(s) & disable fuel injection to affected cylinder(s) before next step.
- Add mixture to radiator, not the overflow tank. If no
radiator cap, detach upper radiator hose and add mix directly into hose. Reattach hose. Start engine and top off with water. Note: If the engine overheats, turn vehicle off, allow engine to cool, top off with water then restart. - Replace radiator cap and idle for 20 to 30 minutes. DO NOT DRIVE OR REV ENGINE.
- Stop engine, let cool, remove radiator cap & open drain.
Reinstall any removed spark plugs. Drain cooling system, but DO NOT flush. - With radiator cap and drains open allow drained cooling system to cure for 24 hours.
- After curing, flush cooling system with water until it runs clear. Reinstall thermostat.
- Drain water then refill with fresh antifreeze/water solution.
- If you have any questions please call CRC Technical Services at 800-521-3168.
Treats cooling systems capacity of 6 gallons or less.
Note: If you are not comfortable following these directions, take this can to your favorite repair shop and ask them to service your vehicle with K&W PERMANENT METALLIC™ BLOCK SEAL.
MONEY BACK GUARANTEE: 800-272-8963.
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