In the same way that you change oil and other fluids, check belts and hoses, and rotate tires on a regular schedule to prevent breakdowns, following a preventative service schedule for your alternator can help prolong its operational lifespan. Every manufacturer has slightly different maintenance recommendations and service intervals, but there are a few general rules of thumb that will work in just about any situation. Some components, like brushes, should be inspected at specific mileage or time intervals, while it may be easiest to perform visual inspections each time the vehicle is in for service.
Following OEM Procedures and Schedules
In some cases, the manufacturer of your alternator may have specific inspection procedures and schedules that you can follow. Although you don’t have to be a slave to OEM schedules or inspection procedures, this is usually a good place to start, and there may be some unique concerns that you need to be aware of. Manufacturers typically also provide specific procedures for testing the normal and full field outputs of your unit.
Simple Visual Inspections
The most common causes of premature alternator failure are heat, vibration, and external contaminants, which can often be avoided through simple visual inspections. That means it’s a pretty good idea to simply give an alternator a once over whenever the vehicle is already down for other service operations.
If the oil- or liquid-cooling system is leaking or impaired, a visual inspection will often reveal the issue before it can cause a breakdown, and it’s similarly easy to check for loose bushings and dirty electrical connections.
Belts and Batteries
Belt tension can affect an alternator in two different ways. If the belt is too loose, the alternator typically won’t charge properly, and if the belt is too tight, it may damage the alternator bearing. In order to avoid these issues, it’s important to tension the belt properly when it is installed and then check it at regular intervals. Manufacturers often recommend checking belt tension every 30,000 to 40,000 miles (50,000 to 65,000 km), but checking it more often may help you avoid a problem.
Since overworked alternators tend to fail prematurely, it’s also a good idea to check the battery and electrical connections regularly. There is no set interval for this type of inspection, but cold weather can push a questionable battery over the edge, so checking your batteries at least once a year in the fall is a good starting point. It’s also important to check all of the electrical connections at the same time.
Preventative Inspection and Replacement of Components
Some alternators are designed so that it’s relatively easy to remove the regulator and brushes for inspection, and others make this procedure more difficult. In either case, checking the brushes every 12 to 24 months, depending on the application, can help prolong the life of an alternator. If the brushes are out of spec, they can be replaced at that time. Other components, like diode trios and rectifiers, are solid state, so they won’t show any visible signs of wear before they fail.