What Repairs Plastic Car Radiator Cracks?

Modern cars use aluminum radiator cores and tubes with plastic end tanks. Repair of minor leaks in the plastic tanks is simple if detected and repaired before it becomes a major failure of the plastic tank.

Cooling System Sealer

Try adding a bottle of cooling system sealer to the radiator fluid in the overflow bottle as instructed on the label. If this seals the leak, go no further, just watch the temperature gauge for overheating.

Preparation for Repair

File or grind the leak into a "v" groove. Sand the groove, then clean thoroughly with grease remover. Allow area to dry.

Epoxy and Fiberglass Repair

Fill the groove with epoxy per label instructions. Smooth out any lumps or troughs in the surface. Allow the epoxy to harden. Spread more epoxy over the groove and add a 1/4 inch border around the groove. When the epoxy sets, cover it with fiberglass. Allow the fiberglass to dry. Run the engine until it reaches its regular operating temperature then check for leaks.