BMW 340i Serpentine Belt
Factory serpentine belt specifications for the BMW 340i.
Last updated: 2026-11-01 • Reading time: 8 min • By AllOEMManuals Editorial Team
Quick Answer
2017-2019 BMW 340i: REMOVING AND INSTALLING/REPLACING ALTERNATOR DRIVE BELT (B48B) (330I XDRIVE WAGON, 330I GT XDRIVE) REMOVING AND INSTALLING/REPLACING DRIVE BELT FOR ALTERNATOR (N47D20 K/U/O/T 1) (328D XDRIVE WAGON) REPLACING DRIVE BELT FOR ALTERNATOR (340I GT XDRIVE).
| Generation | Years | Top spec |
|---|---|---|
| 2017-2019 | 2017-2019 | REMOVING AND INSTALLING/REPLACING ALTERNATOR DRIVE BELT (B48B) (330I XDRIVE WAGON, 330I GT XDRIVE) REMOVING AND INSTALLING/REPLACING DRIVE BELT FOR ALTERNATOR (N47D20 K/U/O/T 1) (328D XDRIVE WAGON) REPLACING DRIVE BELT FOR ALTERNATOR (340I GT XDRIVE) |
This vehicle's factory manual
BMW 340i: choose your year, then confirm the engine, trim, or drivetrain to open the available repair and diagnosis sections.
Know the exact serpentine belt job for your BMW 340i
2017-2019 BMW 340i: REMOVING AND INSTALLING/REPLACING ALTERNATOR DRIVE BELT (B48B) (330I XDRIVE WAGON, 330I GT XDRIVE) REMOVING AND INSTALLING/REPLACING DRIVE BELT FOR ALTERNATOR (N47D20 K/U/O/T 1) (328D XDRIVE WAGON) REPLACING DRIVE BELT FOR ALTERNATOR (340I GT XDRIVE).
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.
2017-2019
Parts and supplies
These links search for related products. Check your year, engine, specification, and fitment with the seller before ordering.
BMW 340i Serpentine Belt
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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 →
Inspect and replace if the service procedure calls for it
- 3Idler PulleyShop →
If it wobbles or squeaks, replace it while you are in there
- 4Breaker Bar (1/2")Shop →
Use the tool specified in the service procedure
- 5Belt Routing DiagramShop →
Take a photo before you remove the old belt
Get everything at once
Search results vary; confirm each item and its fitment before buying.
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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 340i so the job is ready when the parts arrive.
Frequently Asked Questions
- What serpentine belt does a BMW 340i use?
- 2017-2019 BMW 340i: REMOVING AND INSTALLING/REPLACING ALTERNATOR DRIVE BELT (B48B) (330I XDRIVE WAGON, 330I GT XDRIVE) REMOVING AND INSTALLING/REPLACING DRIVE BELT FOR ALTERNATOR (N47D20 K/U/O/T 1) (328D XDRIVE WAGON) REPLACING DRIVE BELT FOR ALTERNATOR (340I GT XDRIVE).
- How do I know if my BMW 340i 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: 2026-11-01