* Size and location of the crack: Very small cracks, especially those not in a high-pressure area, *might* be repairable with a radiator sealant. Larger cracks or those in stress points are almost certainly not repairable.
* Type of material: Radiators are usually aluminum or plastic. Aluminum is more difficult to repair effectively.
* Access: The location of the crack might make repair difficult or impossible.
While radiator repair kits exist, they are often considered a temporary fix at best. The sealant may not hold permanently, especially under the pressure and heat a radiator experiences. A poorly repaired radiator could lead to further damage, overheating, and potentially a catastrophic engine failure.
In short: For a small, minor crack in an accessible location, a sealant *might* buy you some time. However, replacing the radiator is almost always the better and more reliable solution. The cost of a new radiator and installation is usually far less than the potential cost of engine damage from a failed repair. Consider the risk and cost of a potential failure versus the cost of replacement.
