These little guys are really simple, honestly. They create a seal. Specifically, they seal around where the alternator housing parts meet. They prevent oil—and sometimes coolant—from leaking out, and also keep dirt and moisture from getting in. It’s just a rubber ring, but it’s surprisingly effective. Think of your alternator as the heart of your electrical system. It needs to stay clean and lubricated to do its job, and the O – ring is a key part of making that happen. It sits in a groove, squeezing between those metal surfaces to maintain that seal. It’s positioned around where different sections of the alternator bolt together—often around the rear housing or where the rectifier assembly fits. Well, if this little ring fails, you’ll likely start seeing oil leaks. That’s the most common symptom. It can cause a mess under your hood, and eventually, if you lose enough oil, the alternator can overheat and fail. It's a small, inexpensive part, but a failed one can lead to a really big problem. You'll notice if it's leaking – you'll probably smell burning oil, or just see it pooling somewhere. A lot of people find these while doing other maintenance and replace them as preventative work. You can usually find them pretty easily online, places like Fixparts Online carry a good range of sizes for different alternators. It's one of those things where spending a few bucks now can save you a lot of hassle later. Backed by trust: O-Ring (MPN 11611730725) comes with a 12-month warranty!

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• Get parts made specifically for your BMW, so they fit and work perfectly. • BMW parts are known for their high quality and durability, meaning they last longer. • Using genuine BMW parts helps maintain your vehicle’s value. • You can trust BMW parts to keep your car running smoothly and safely. Drive with confidence – choose BMW parts at FixParts Online.