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BMW 740il Alternator

Pinpoint BMW 740il Alternator Problems Instantly

Comprised of diodes which can exert 12 to 14 volts DC, the BMW 740il alternator powers various electrical components in your car such as a power sunroof, built-in DVD player, and heated seats. More importantly, the alternator is responsible for providing your car batteries with the necessary electrical charge. When the alternator of your car goes bad, you can expect a number of malfunctioning symptoms such as misfire and an ABS light on. It can even get worse and cause start failure because of the uncharged car battery. To help you figure out what's wrong with your BMW's alternator, here are some signs to watch out for and what they usually indicate:

Reduced voltage output

Your BMW 740il's alternator has diodes inside it that transform the alternating current into a direct current. This conversion leads to the creation of a charge that powers the battery. To check if the alternator is bad, disconnect the battery while the vehicle is running. If the car continues to run like nothing happened, then your alternator is doing just fine. However, if the vehicle immediately stalls and shuts off, then your alternator is obviously busted.

Sustained grinding noise

The alternator has a rotor inside it, which spins on a set of ball bearings. When these bearings within the alternator become worn, they can "catch" as they develop flat spots. This results in a horrible racket and can turn into a sustained grinding noise. Verify bad alternator bearings using a tubing to listen for noise. While your car is in idle, put one end of a 12-inch piece of tubing near the alternator, while the other end of the tubing is placed near your ear. If the noise is louder near the alternator, then that's an indication of a bad alternator.

Lost ground

When your car's alternator loses ground, it can lead to expensive damage as the alternator surges, posing a malfunction possibility to the voltage regulator inside it. Inspect your alternator's primary mount to see if it's still wired to the vehicle's frame. A large cable usually connects the alternator to the car. Over time, this cable can become loose or disconnected. Make sure that you tighten the connection of the ground wire to the alternator mount, and inspect it regularly.

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  • Keeping Your BMW 740il Alternator in Optimum Condition 04 March 2014

    Your car's alternator is responsible for powering the electrical system in your vehicle. It's capable of supplying electrical charge to various small devices in your car. Moreover, your BMW 740il alternator recharges your vehicle's battery so that you won't get stranded somewhere with a drained and uncharged battery. Below are some tips to preserve your alternator in its best condition.

    • Limit electrical devices to a few.
    • Obviously, the more electrical devices connected to your car, the greater the drag to the alternator. The lifespan of the alternator or the age of the battery may be shortened due to excessive electrical loads. Keep the electrical devices to a minimum, and make sure that only the necessary ones are frequently used.
    • Check the alternator's drive belt tension.
    • Whenever you're going for oil change, make sure that the alternator's drive belt tension is also inspected. This is because a loose drive belt may lead to the alternator producing a reduced output. Remember that in order to charge the battery, the alternator must put out the appropriate amount of current and voltage.
    • Avoid draining the battery.
    • The alternator in your vehicle is designed to charge the battery after slight discharging such as starting the engine. It's not built to charge heavily a discharged battery or dead batteries. The alternator may overload and get damaged if you rely on it to charge heavily discharged batteries or dead batteries. If your car's battery gets drained, then use a battery charger instead.
    • Use a voltmeter to measure the alternator's voltage.
    • Start the vehicle and make sure that all electrical devices are turned off. Let the engine idle. Set the voltmeter on DC scale and connect it to the battery terminals. The voltmeter should get a reading of around 14 volts. Then, start turning on electrical devices such as headlights, radio, and heater. Observe the voltmeter's reading. If the voltage drops below 12 volts at any time, then the alternator has malfunctioned. Repair or replace it immediately to prevent expensive damages.
    • Regularly inspect the alternator for wear or damage.
    • The average alternator usually lasts for 75,000 to 100,000 miles. Check the alternator housing for cracks, leaks, and signs of corrosion. These symptoms of wear and damage can turn into a whole brake system failure if not attended to immediately.