Engine Belts

All vehicles have an accessory belt that drives features such as the alternator and air-conditioning compressor, and perhaps the power steering and water pump. This belt is usually mounted externally so you can see it on the front end of the engine (the engine is mounted transversely on most front-wheel-drive vehicles), and it usually is a serpentine belt that slithers around various pulleys. It needs to be replaced when it shows wear, such as cracks, fraying or stretching.

Replacing a timing belt is a more involved and costly procedure, typically running from at least $500 to more than $1,000, depending on vehicle. Even worse, on some engines if the timing belt breaks, the pistons may continue to move up and down, and in the process bend valves that have lost their timing mechanism. That can add up to big bucks, possibly $3,000 or more.

That makes timing belt replacement more critical, but because it is not visible you can't easily check it. That involves removing the accessory drive belts, the engine cover and other hardware just to get a look at it, and no repair shop is going to do this for nothing (they also have to reassemble everything). That is why you should pay close attention to the manufacturer's recommended replacement schedule. Here, too, recommendations vary. Some Honda V-6 engines call for timing belt replacement at 60,000 miles, for example, but the 1.8-liter four-cylinder used in some Chevrolets lists it at 100,000 miles.

With some engines, the timing belt also drives the water pump, so repair shops may recommend that the water pump be replaced at the same time as the belt.