BMW Engine Crankshaft Main Bearing - Genuine BMW 11211725909

Product Information

BMW Engine Block and Components diagram for 540i, 740i, 740iL, M5, X5, Z8

An engine crankshaft main bearing is a crucial component that supports the crankshaft in the engine block and allows it to rotate smoothly. These bearings are typically metal shells lined with a soft, durable material (like babbitt or a copper-lead alloy) and sit between the crankshaft journals and the engine block, and helps maintain proper oil clearance for lubrication.

• Knocking or Thumping Noise from Engine (Rod Knock or Main Knock): Often heard at low RPM or under load; a classic “engine knock” indicates excessive bearing clearance.
• Low Oil Pressure: Worn bearings increase oil clearance, causing a drop in oil pressure readings.
• Metal Shavings in Oil: Bearing material can wear off and contaminate engine oil.

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You may not realize this, but the parts that make up your BMW are not necessarily manufactured by BMW. No cause for concern, as BMW designs the part, hires a manufacturer, and ensures its quality to you. In fact, many of these manufacturers have been making parts for BMW for decades. In our industry these manufacturers are called OEM (Original Equipment Manufacturers), and these are often brands you recognize, including Lemforder, ZF, Sachs, Bosch, Valeo, Zimmermann, Siemens VDO, Corteco, and more. Don’t be surprised to open that Genuine BMW parts box and find an OEM branded part inside, simply with the addition of a BMW logo.

Be sure to keep an eye out for OE tags on our product pages to quickly identify parts coming direct from OE manufacturers. That extra bit of insight could save you some serious money while shopping! Refer to our OE Academy for further information regarding the OE/OEM tags throughout the site.