BMW 540i Serpentine Belt
Factory serpentine belt specifications for the BMW 540i.
Last updated: 2026-10-29 • Reading time: 8 min • By AllOEMManuals Editorial Team
Quick Answer
2017-2022 BMW 540i: B46/B48 engine (except PHEV): REPLACING DRIVE BELT FOR ALTERNATOR B46/B48 engine (PHEV): REMOVING AND INSTALLING/REPLACING DRIVE BELT FOR COOLANT PUMP (2018-2020) , or REMOVING AND INSTALLING/REPLACING DRIVE BELT FOR COOLANT PUMP (2021-2022) B58 engine: REPLACING DRIVE BELT FOR ALTERNATOR (540i, 2017-2022, 540i xDrive 2021-2022) , or REPLACING DRIVE BELT FOR ALTERNATOR (540i xDrive 2017-2020) N63 engine: REPLACING DRIVE BELT FOR ALTERNATOR (2018-2019) , or REPLACING DRIVE BELT FOR ALTERNATOR (2020-2022).
| Generation | Years | Top spec |
|---|---|---|
| 2017-2022 | 2017-2022 | B46/B48 engine (except PHEV): REPLACING DRIVE BELT FOR ALTERNATOR B46/B48 engine (PHEV): REMOVING AND INSTALLING/REPLACING DRIVE BELT FOR COOLANT PUMP (2018-2020) , or REMOVING AND INSTALLING/REPLACING DRIVE BELT FOR COOLANT PUMP (2021-2022) B58 engine: REPLACING DRIVE BELT FOR ALTERNATOR (540i, 2017-2022, 540i xDrive 2021-2022) , or REPLACING DRIVE BELT FOR ALTERNATOR (540i xDrive 2017-2020) N63 engine: REPLACING DRIVE BELT FOR ALTERNATOR (2018-2019) , or REPLACING DRIVE BELT FOR ALTERNATOR (2020-2022) |
This vehicle's factory manual
The spec is above. This opens the 2017 BMW 540i factory book. Use another year if yours is older.
Know the exact serpentine belt job for your BMW 540i
2017-2022 BMW 540i: B46/B48 engine (except PHEV): REPLACING DRIVE BELT FOR ALTERNATOR B46/B48 engine (PHEV): REMOVING AND INSTALLING/REPLACING DRIVE BELT FOR COOLANT PUMP (2018-2020) , or REMOVING AND INSTALLING/REPLACING DRIVE BELT FOR COOLANT PUMP (2021-2022) B58 engine: REPLACING DRIVE BELT FOR ALTERNATOR (540i, 2017-2022, 540i xDrive 2021-2022) , or REPLACING DRIVE BELT FOR ALTERNATOR (540i xDrive 2017-2020) N63 engine: REPLACING DRIVE BELT FOR ALTERNATOR (2018-2019) , or REPLACING DRIVE BELT FOR ALTERNATOR (2020-2022).
Belt routing and length change with engine code, accessory package, and tensioner layout. Do not order parts off a generic diagram. Once the spec is confirmed, use the supplies and purchase links below to build the full one-trip shopping list before you start the repair.
Exact Vehicle Check
The button opens the factory book for this vehicle. Use the engine picker only when your trim is not the one this page already matched.
2017-2022
Manual already checked Amazon for you
You came here for the exact spec. Now here is the exact part — plus the two things people always forget and have to run back to the store for.
BMW 540i Serpentine Belt
Match the exact belt length and rib count for your BMW 540i engine.
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Serpentine Belt — Manual's Parts List
Belt, tensioner, and the tool to do it right.
- 1Serpentine BeltShop →
Exact length and rib count for your engine
- 2Belt TensionerShop →
A weak tensioner ruins a new belt in 2,000 miles
- 3Idler PulleyShop →
If it wobbles or squeaks, replace it while you are in there
- 4Breaker Bar (1/2")Shop →
Tensioners need leverage — a ratchet will not cut it
- 5Belt Routing DiagramShop →
Take a photo before you remove the old belt
Get everything at once
One search shows all of the above on a single page.
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One-Trip Shopping List
Recommended supplies and tools for this job, grouped so you can buy everything before the repair starts.
Exact Serpentine Belt
Match engine-specific length and rib count for the cleanest fit.
Belt Tensioner
Replace weak spring-loaded tensioners that cause squeal and slip.
Idler Pulley
Quiet bearing support when the belt is off anyway.
Pulley Puller Set
Useful for stubborn idler and tensioner pulley swaps.
Breaker Bar
Makes tensioner release easier in tight engine bays.
Shop Towels
Keep the accessory drive and your hands clean during inspection.
Project Essentials
Basic tool sets, gloves, and cleaning supplies for your BMW 540i so the job is ready when the parts arrive.
Frequently Asked Questions
- What serpentine belt does a BMW 540i use?
- 2017-2022 BMW 540i: B46/B48 engine (except PHEV): REPLACING DRIVE BELT FOR ALTERNATOR B46/B48 engine (PHEV): REMOVING AND INSTALLING/REPLACING DRIVE BELT FOR COOLANT PUMP (2018-2020) , or REMOVING AND INSTALLING/REPLACING DRIVE BELT FOR COOLANT PUMP (2021-2022) B58 engine: REPLACING DRIVE BELT FOR ALTERNATOR (540i, 2017-2022, 540i xDrive 2021-2022) , or REPLACING DRIVE BELT FOR ALTERNATOR (540i xDrive 2017-2020) N63 engine: REPLACING DRIVE BELT FOR ALTERNATOR (2018-2019) , or REPLACING DRIVE BELT FOR ALTERNATOR (2020-2022).
- How do I know if my BMW 540i serpentine belt is bad?
- Common signs include squealing on startup (especially when cold), visible cracks or fraying on the ribbed side, power steering or A/C failure, and battery warning lights. The factory manual includes inspection criteria and replacement intervals.
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Author & Review
Published by AllOEMManuals, founded by Lyndon Bedford, an automotive technician with 20 years of experience. He owned and operated a mechanic shop in Hurst, Texas from 2014 to 2022 and continues hands-on repair work.
Content may combine manual references, general repair templates, and AI-assisted drafting. Confirm the source, vehicle configuration, and applicability before working. Report corrections through our contact page.
Last updated: 2026-10-29