Although most current vehicles utilize aluminum radiators, here's a look at some of the most common failures of the older style copper/brass radiators

SEAM LEAK: 
This is a solder joint failure between the tank and the header. It can be caused by a poor solder joint at the seam, corrosion or a stress crack. If the rest of the radiator is in good condition and not limed up too badly inside this type of leak can be repaired by removing the tank, cleaning up the header and tank and reassembling the radiator.

INLET/OUTLET LEAK: 
This is a solder joint failure at the hose connection. The cause of this type of failure could be a poorly soldered joint, radiator hose vibration or cracking due to excessive stress or pressure on the connection. It is easily repaired by first checking the affected area for cracks, if no cracking is found thoroughly clean and resolder the connection. 

TUBE RESTRICTION:
Lime or calcium build up on the ends of the tubes can restrict coolant flow through the radiator core and will lead to overheating or a possible boil over situation. Solder bloom is a chemical reaction between the solder, brass header and anti-freeze. This white growth will eventually plug the ends of the tubes. Proper cooling system maintenance, including flushing the cooling system and refilling with the correct mix of quality anti-freeze and distilled water will prevent most of this from happening.

CRACKED TANK: 
This is plastic rad tank failure caused by plastic fatigue. The condition is due to constant heating and cooling which will eventually cause the plastic to become brittle and crack under pressure. In some cases the plastic rad tank can be replaced. If a new tank is not available, a new complete radiator is recommended.

RAD CORE DAMAGE: 
This can be caused from a fan blade striking the core, a stone hitting the rad, something rubbing against the core or a foreign object contacting the rad. If the damage is not too severe, this is a fairly simple repair providing the rest of the radiator is in good condition. 

TUBE LEAKS: 
This could be a leak between the tube and the header, or possibly a corroded tube at the header. If your core is aluminum, this type of leak would require a rad replacement. If your rad core is copper/brass, it can be repaired providing the rest of the radiator is in good condition.

FIN DETERIORATION: 
This condition is common with rads that are 4 to 5 years old and are exposed to road salt during winter weather driving. The salt will eventually deteriorate the fin material and severely weaken the rad core. The area most affected would be the lower half of the rad as it is most vulnerable to the splash of slush and water that is mixed with road salt. To repair this damage would require either recoring the rad or replacing it with a new complete rad.

PLUGGED RAD CORE: 
This is another example of a plugged rad core. This restriction has been caused by the over use of a radiator "stop leak" additive. You can see the sealer has actually collected in the lower section of the tank, blocking off those tubes and not circulating as it was designed to do. Most stop leak products only provide a temporary fix and rarely result in a long lasting permanent repair. A new complete rad in this case would make the most sense.

LOOSE SIDE STRAP: 
This is a common problem on down flow type rads. It is caused by a poor solder joint or excessive twisting of the rad support causing the solder joint to break. To repair this we simply clean the strap and the tank, secure the bracket into place and resolder the strap to tank connection.

PLASTIC TANK FAILURE: 
This is another common problem on today's modern rads. High coolant temperatures eventually break down the plastic causing it to crack, or in some cases break the connection completely off the rad. If the cooling system loses too much coolant, the resulting super heated steam will actually melt or erode a hole right through the plastic tank and this can quite possibly end up causing severe engine damage.