The reasons technicians source from the dealership are many, but one of the most common reasons is availability. Techs buy from the dealer in some cases solely because they think they have no other option. Sometimes this is true, but other times it is not, as in the case of timing components.
In fact, prior to the launch of its timing component kit line, Dayco found that as much as 85 percent of timing component sales were going to the OE dealer.
"So many mechanics and service centers believe this is a dealer-only item. Clearly they are available through traditional distribution," said Ed Rammel, Dayco's vice president of marketing. "They should go to their traditional supplier to get them, as opposed to going to the OE dealer."
Component kits are available for most timing belt system replacement applications. In fact, a survey of technicians showed respondents are more likely to perform a complete timing belt system replacement when application specific components are available as a kit, reducing the chance for mismatched parts.
Timing belts can have one of several different teeth profiles in addition to different lengths and widths. If there's a mismatch between the belt and drive sprockets, tensioner or idler pulleys, it will ruin the belt. With a kit, you and your customer know that all the components will work together perfectly.
Tensioner bearings are "sealed for life" and are not serviceable, so there's no way to clean, inspect or re-lubricate the bearings when a timing belt is changed. On many newer engines, spring-loaded automatic tensioners are used to keep the timing belt tight. If the slide plate is worn or sticking, or the spring is weak, it can prevent the tensioner from maintaining proper pressure. Some vehicles use a hydraulic tensioner that is pressurized by oil pressure. If it leaks, it could destroy the belt. Always inspect for leaks around the plunger and shaft. It's difficult to determine the true condition of the tensioner components when they are not running under a load. Consequently, a simple visual inspection may miss tensioner bearings that are on the verge of failure. Kits make replacement of these components easy.
Finally, replacing the tensioner and idler pulleys along with the belts will restore the timing belt drive to like-new condition and significantly reduce the risk of future problems. Many technicians don't replace these components then wonder why the new belt they installed failed a few thousand miles later.
For the parts store, component kits make a lot of sense because of the lower number of SKUs required for coverage. Greater availability in the aftermarket draws attention from technicians, who often demand same-day delivery.
Anybody who's replacing an OHC timing belt should also consider replacing the water pump at the same time if the pump is located under the belt - even if the pump is still good. Why? To save labor. The service life of the water pump and belt are about the same, so why tear the engine apart twice if you can do both jobs at once?
In addition to a timing kit, your customer may also need a timing cover gasket set (unless he's replacing a belt only on an OHC engine), and possibly a water pump and pump gasket set (depending on the application). If the customer is building a performance smallblock Chevy V8, you might recommend an aftermarket two-piece timing cover that allows easier access to the cam sprocket for making timing adjustments, or a dress-up cover (finned aluminum or chrome-plated steel) to dress up the engine's appearance.
Because of the location of the timing components under the engine's front cover, your customer may also find it necessary to replace the engine's coolant, and other belts and hoses, too.