Battery, Starter, Alternator Troubles
A starter that's failing may crank the engine too slowly for a quick start, or it may not crank the engine at all. Often, the problem is not the starter but a low battery or a loose or corroded battery cable connections. So, check the battery change and condition first.
A good battery should be capable of accepting and holding a charge from a battery charger, and should be at least 75% charged at 12.5 volts or higher. If the battery's voltage is low and it doesn't take a charge, your customer needs a new battery. Load-testing the battery or using a conductance tester to check its ability to take a store a charge can also confirm the need for replacing the battery. The average service life of a car battery is only about 4 to 5 years, and can be shorter in hot climates.
High resistance within the starter itself, worn brushes, or grounds or opens in the armature or coil windings can cause excessive current draw. It can also result from increased internal friction due to shaft bushings that bind or an armature or magnets that are rubbing inside the starter. A loose starter may crank an engine slowly, noisily or no at all. Loose bolts will make for a weak ground connection. The starter may also flop around, slip, chatter or fail to engage depending on how loose it is. Sometimes the engine won't crank even thought the starter will spin. This is usually an engagement problem due to weak solenoid or a defective starter drive. A starter drive that is on the verge of failure may engage briefly but then slip. The starter drive has a one way overrunning clutch mechanism that you can check once the starter is out of the car and replaced if necessary. The drive should turn freely in one direction but not in the other if good. A bad drive will turn freely in both directions or not at all. If a drive locks up, it can over-rev and destroy the starter.
The first sign of trouble when an alternator is failing is a low or dead battery. On a late module vehicle, that can not only cause a no-start but also can cause the loss of "learned" data in the powertrain control module and other modules throughout the vehicle. Ins some cases, certain modules may not regain their normal function after the battery has been recharged because the module requires a special releam procedure. The output of the charging system on a vehicle can be checked while the engine is idling. A charging system that is working properly should produce a charging voltage of somewhere around 13.5 to 14 volts at idle with the lights and accessories off. When the engine is first started, the charging voltage should rise quickly to about two volts about base battery voltage, and then taper off, leveling out at the specified voltage.
A lipping drive belt is another common cause of undercharging, especially with V-belts on older vehicles. Serpentine belts usually provide a better grip, but if the automatic tensioner is weak or stuck it can allow the belt to slip under load. Glazed streaks on the belt or belt noise when high-load electrical accessories are turned on with the engine idling can be signs that the belt is slipping. Ask your A-! Auto repair ASE certified technician for any repair questions and repair needs.