What brings customers in for cooling system repairs? Usually, it's a cooling system problem. No vehicle will go very far if its cooling system isn't working. Sooner or later, the engine will overheat - possibly with dire results. Severe overheating can damage the cylinder head, head gasket, pistons, cylinders and/or valve guides. Many motorists don't realize how serious overheating can be, and few know even about what might be causing their cooling problems.

Cooling problems can be lumped into two categories: coolant leaks and overheating. The first will ultimately lead to the second. But until the loss of coolant is large enough to cause the engine to run hot, a few drops of coolant on the driveway may not seem like a big deal. Nothing could be further from the truth.

Most passenger cars today have relatively small cooling systems. Radiators have been downsized and made more efficient to save weight and improve fuel economy. Consequently, most cooling systems have little margin for error if the coolant level gets low either because of neglect or leaks.

The coolant level should be checked periodically at the coolant reservoir, and additional antifreeze and water (or pre-mix) added as needed to maintain the system at the proper level. Over time, all cooling systems will need a little make-up coolant. But if nobody checks the level and it gets low, trouble will soon follow.

On some vehicles, a low coolant leve...