This little guy's job is to keep the timing chain nice and tight. The timing chain connects the crankshaft to the camshaft, and it needs to have just the right amount of tension. The tensioner uses an oil – pressure system, usually with a ratchet mechanism, to push against the chain and take up any slack. It constantly adjusts, basically keeping everything lined up properly. It’s a critical part of your engine's timing system. That timing is what controls when the valves open and close, and when the spark plugs fire. It’s all about getting everything to happen at exactly the right moment, and the tensioner is a key player in making sure that happens smoothly. Think of it like this: the tensioner acts like a shield, preventing the chain from flopping around and potentially causing a lot of damage. If this thing fails, or even gets weak, you’re looking at serious trouble. A loose timing chain can throw off the engine timing, leading to reduced performance, poor fuel economy, and even engine damage. You’ll notice if it's going bad – often it’ll start with a rattling sound, especially on startup. If it breaks or fails completely, your engine could stop running, and in some cases you could have catastrophic engine failure. It's one of those parts that’s relatively inexpensive to replace compared to the cost of repairing a damaged engine. You can often find a good replacement, like the ones we have over at Fixparts Online, and it’s a job most experienced DIYers can handle, though it’s not the easiest. All-season performance: Rail (MPN 11317504461) 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. Performance you can rely on – BMW parts from FixParts Online.