BMW Alternator - Valeo 12311744565

All internal combustion engines need fuel, air, and an electric spark to create the horsepower and noise we love so much. The 12-volt batteries that power our cars don’t have enough electricity to power a car for years on end, so alternators are our workaround. Unfortunately, they aren’t the most reliable engine bay occupant, so replacements are fairly common on older vehicles with lots of miles on them. 

BMW E36 Alternator Failure

Alternators are relatively simple pieces of equipment that carry an enormous job. They’re driven by a belt as the engine runs, generating electricity that keeps the battery charged and nearly all systems in the car functioning. When they fail, there’s a concise window of time before your BMW E36 shuts off completely, but they hardly ever fail at a moment's notice. Typically, there’ll be a few signs well beforehand.

BMW E36 Alternator Failure Symptoms

• Low battery light soon after a battery replacement

• Low battery, check engine, and e-brake lights all illuminating within minutes of each other

• Dimming headlights/interior lights

• Less than 13 volts at the battery while the engine is running

• Whirring or buzzing from the alternator while operating

All of the alternator failure symptoms revolve around the electrical systems, so any issue related to them can be the start of a problem in the charging system. Many of the signs also point to a failing battery. Here’s how you can differentiate between the two issues. Their lifespan is also shortened by regular usage at high RPM. Whether sliding around in your M52-powered 328i or bumping fenders in your S52-powered M3, living at the limiter will require more frequent replacements. 

BMW E36 Valeo Alternator Replacement

Regardless of how the alternator fails, a replacement will be necessary. Luckily, the M52 and S52 alternators in the E36 are easily accessible, sitting just below the intake airbox. The rest of the BMW alternator replacement process is straightforward, especially with this Valeo alternator. However, before purchasing this unit, ensure a Valeo alternator is already equipped in your BMW.

Bosch and Valeo were OE alternator suppliers to the BMW E36 chassis; however, their mounting style is slightly different. The Bosch’s lower mounting hole is threaded, but the Valeo’s isn’t and uses a different bolt with an external nut. You can swap between the Valeo and Bosch, but you’ll need the correct hardware to go with it.