Belts play an important role in keeping the engine humming smoothly. They drive the fan, alternator and water jump - three items that must function for your engine to run. And in cars with power steering and air conditioning, belts also drive these units.

Unfortunately, many people ignore their belts until something drastic goes wrong. That's a bad policy, because if a belt breaks it can cause overheating (the fan and water pump stop), electrical problems (the alternator charges the battery only as long as the belt turns its pulley), and loss of the air conditioner and power steering pump.

Periodic inspection and automatic replacement of belts every two years is almost a 100 per cent guarantee against belt failure. Inspecitng your belts is easy. You're looking for two things - proper tension and wear.

To check tension, the engine should be off and the ignition keys in your pocket.

Grasp each belt midway between two of its pulleys. Use your thumb and forefinger to hold the belt. Move the belt up and down. It shouldn't move more than half an inch. If it does move more than this, adjust belt tension until you get a little less than half an inch of movement.

To inspect the belts for wear, grasp each belt and turn its underside up so you can see it. If the underside is slick, shiny, cracked, chipped, frayed or covered with oil or grease, the belt should be replaced.

To get replacement belts just drive over to your local auto parts store or parts department of a dealer that handles your make of car. Tell the person at the counter your engine make, displacement, and what accessories you have, such as air conditioning and power steering.

To replace belts, loosen the bolts that hold the alternator and other pulleys in place. This lets you move the pulleys to release belt tension and you can pull the belts off. Remove one belt at a time and keep the belts in order. Then match up the new belts with the old ones and put the belts back on in the reverse order that you took them off.

Double check to make sure you have the belts in their proper pulleys and that they aren't out of alignment with their respective pulleys. Place a pry bar between a solid part of the alternator and a solid part of the engine and force the alternator out until the belt tension is such that you can move the belt up and down, a little less than half an inch, then tighten the bolt that holds the alternator in place.

Be careful when using the pry bar not to pry against any electrical wires or fluid lines. After you've driven the car a few times, recheck and readjust.