I have an installer customer who stocks timing kits. Let that sink in for a moment. Not just oil filters, light bulbs and wiper blades. Timing kits. Granted, he specializes in one make, and he’s pretty far out of town, so it pays for him to have things handy that he knows he will use.

Now, I’m not saying your store’s outside salesperson needs to start writing up timing kits on every stock order, but it leads me to my point. Timing belts are considered a regular maintenance item. Timing belts should be replaced according to the manufacturer’s service recommendations, which may range anywhere from 50,000 to 120,000 miles.

Many professional installers already have access to these individual recommendations, but your retail customers may come to you for replacement interval advice. Your belt and hose vendor likely offers some sort of resource, either printed or electronically, with the mileage intervals listed by application. One major aftermarket manufacturer also recommends that belts in service more than six years (regardless of mileage) are prime candidates for replacement, due to the rubber and fiber degrading as they age.

Another common concern is whether or not the vehicle is an interference engine design. In an interference engine, clearance between the pistons and valves is minimal. During normal operation, this clearance poses no issue. However, in the case of a broken, slipped or loose belt, the resulting loss of synchronization between the camshaft(s) and crankshaft may cause catastrophic engine damage as the pistons and valves suddenly try to occupy the same space in the cylinder.

This is a major reason to recommend the timing belt be changed according to the advertised OE replacement intervals. Interference engine applications are usually highlighted in catalogs to draw attention to this fact. Timing belt failure in free-wheeling engines will not cause the extensive valve and piston damage of an interference engine, but it may still damage other components inside the timing cover.

Planned preventative maintenance now surely beats an unexpected breakdown and extensive repair bill later. Timing components are available in a number of individual and kit forms, offering the flexibility to replace just the timing belt or overhaul the entire timing drive system. Pieces like pulleys and tensioners are often available individually, for situations when a complete kit is not required.

The most complete kits will include the belt, all associated pulleys and tensioners, seals and gaskets, as well as the water pump. Many modern engines rely on compact design, so it has become increasingly common for the water pump to be driven off the timing belt in order to save space. For such applications, offering the complete kit including the water pump makes for a more complete repair and provides both the installer and the vehicle owner with savings.

The kit option often offers a better value when compared to purchasing components individually, and replacing the water pump while the timing service is being performed is more economical than performing each repair individually. Timing component replacement can be very time- and labor-intensive, so having all of the necessary components in one package can save the technician time and stress. Given the precise nature of the timing drive, the labor involved, and the consequences of a failure, it is a job that nobody wants to do twice.

While it is up to the technician to perform the necessary repairs, it is the parts specialist’s responsibility to make sure that the parts provided are correct as well as complete. The number of components in a timing kit can vary wildly from application to application, so be sure to communicate to your customer just what is (and is not) included in the kit. Beyond compiling the customer’s parts list, it is important to positively identify the engine and application. Many OEMs have incorporated running design changes in their timing drives, which present multiple catalogue options, even within the same model year.

Some are as simple as an engine code, a VIN break or a “before and after” production date, while others require physical comparison of component features. For belts, differences in tooth count or shape are common, as are the differences between hydraulic or mechanical belt tensioners. In cases where the OEM or even an aftermarket manufacturer has redesigned or upgraded a particular component, it may be necessary to refer to catalog footnotes, or even the installation instructions to determine the suitability for your application.