Instead of attempting a repair, your best course of action is replacement. Attempting a repair is generally more expensive and time-consuming in the long run than simply replacing the faulty unit.
While some products advertise repairing plastic, they are generally only effective for very small cracks or hairline fractures under low pressure, and even then their longevity is questionable. The heat and pressure within a radiator make a successful, long-lasting repair extremely improbable.
If you're determined to explore options beyond replacement (strongly discouraged):
* Professional repair: Contact a qualified heating and cooling technician. They may have specialized techniques or access to better materials, but even then, replacement is usually the recommended solution.
* Welding (very unlikely to succeed): Some plastics *can* be welded, but this requires specialized equipment and expertise and is highly unlikely to create a reliable seal in a radiator under pressure and heat.
In summary: Don't try to repair a cracked plastic radiator yourself. It's a safety hazard and likely won't work. Replace it.
