The radiator is the circulatory storage facility for the cooling system in your vehicle. Its primary job is to help keep the engine from overheating, but it also provides heated coolant to the heater core, which is the source of heat for the cabin. Because the radiator most commonly sits in the front of the engine compartment, it is susceptible to the elements. Often times, a radiator will deteriorate from age more than it will from mileage. Either way, a leaking radiator should be repaired or replaced.
Finding the Leak
Depending on the coolant used in your vehicle, a telltale sign of a radiator leak will be a puddle of bright green, pink or orange on the ground below the engine. Be sure to clean up those puddles, as engine coolant is toxic.
Once you've discovered you have a leak, the next challenge is to locate it. Because the radiator is positioned next to the cooling fans, blow-back from the fans may spread the coolant all over the place making it difficult to locate the source of the leak.
Often times, corrosion occurs on metal radiators near the seam. Because the seam runs around the entire perimeter of the radiator, finding the point of the leak may be difficult.
You can use a cooling system pressure tester if available. Hose down the radiator with a garden hose, remove the radiator cap -- making sure the radiator has cooled down and pressure is slowly purged from it -- and then placing the cap of the pressure tester onto the radiator neck. Pump the tester a few times until it reaches the proper pounds per square inch; 15 pounds of pressure should be adequate to locate the leak. Once the radiator is pressurized, you'll see a steady stream of coolant purging out from the leak.
Fixing the Leak
There are a number of ways to fix a leaking radiator. A cold-weld can be used, or you could solder the leak in the seam. The best way to repair a radiator is externally. Pouring a bottle of radiator sealant into the radiator is never recommended by qualified technicians. Although it may help to seal the radiator leak, it almost always will damage other components in the cooling system. Soldering the seam or corroded leak usually requires the removal of the radiator. Because of that, you have to ask yourself why you're repairing a radiator instead of replacing it if you have to go through all of that trouble. Although a new radiator can be expensive, the labor to remove and repair one is going be almost as expensive as installing a new radiator.
Is a Repair Worth it?
If you're not in a position to repair the radiator yourself, you can add at least three hours of labor costs to repair your old radiator once it's out of the vehicle, which may make the overall costs the same as buying a new radiator.
Almost any repair performed on a radiator is a temporary one. If the leak occurred from corrosion, that may be an indication there are other compromised areas of weakness in or on the radiator.
Once a radiator has formed a leak, the absolute best repair is to replace the radiator with a new one.
