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BMW’s 4th generation M3 has almost all the best traits of highly desirable enthusiast cars. Even as early examples approach 15 years of age (at the time of writing), their value has remained relatively stable, thanks to their unique offerings. But with that uniqueness comes bespoke parts engineered for performance. In many ways, that’s good, but not when it comes to time for service.

Very few components on the E9X (E90, E92, E93) M3 are shared with more widely produced E9X 3-series models, and when you factor in economies of scale, there’s no wondering why those bespoke parts cost more. That said, not every M3 service or repair means draining your rainy day fund just to get the car back on the road. Thinking outside the box can save you a lot of money, and we’re here to help you.

 

BMW E90 M3 Accessory Belt System

A standard maintenance item on all cars is the accessory drive system, which consists of a drive belt, pulleys, and one or more tensioners. Each component within the system is a wear item that will require replacement at some point in any vehicle's service life. These items wear together, and we highly recommend replacing them simultaneously. On many cars, service is no problem as the cost of the parts is relatively low, and the system is simple, but that's not the case for the E9X M3. 

On the non-critical accessory side of the accessory drive system (blue), the E9X M3 uses one of two power steering pumps, which were determined by a production date split on 5/15/2008. On the critical side (red) of the accessory drive system, all E9X M3s use the same parts. 

One of the most expensive parts of this system is the belt tensioner pulley. For whatever reason, BMW won’t sell the pulley separate from the tensioner arm, making replacement unnecessarily costly. They’re only available as Genuine BMW components, and replacing both tensioner lever arms will run you north of $400. It’s a real headache because the tensioners are often still in good shape when the pulley’s bearing wears out. BMW doesn’t provide replacement parts for these tensioner pulleys, so you’re out of luck—or so the internet would have you believe. 

 

BMW E90 M3 Accessory Belt Tensioner Pulley Replacements

Fortunately, the pulleys themselves are removable from the lever arm via the M10x1.5 screw affixes them. Common sense made me think that the pulley was replaceable on its own, so I did some digging and found a solution that’ll save you almost $400 the next time your accessory pulleys wear out.

As it turns out, only two pulleys are used across the various tensioners on the front of an S65. Shared across all models is the tensioner and pulley for the critical side of the accessory system. The tensioner assembly (p/n 11287838194) uses a pulley marked F-233151.06. It’s sold independently as INA 5320342100 and cross-references to a BMW idler pulley (p/n 11281440237). It’s also the same pulley used on later production (counter-clockwise) E9X M3s for their revised non-critical side tensioner. The early production (clockwise) E9X M3s use this tensioner arm (p/n 11287838196) on the non-critical side. It uses a pulley marked F-553814.03, which is INA 5320557100, and cross-references to a VAG idler pulley (059903341G/95510211921). 

For both non-critical tensioners, replacing only the pulley will cost a bit under ten percent of replacing the entire arm assembly. When replacing them, you’ll want to pull the assembly out of the car as there’s more room to work. Owners of later cars could especially benefit from this as there’s a backing plate that also has to come out with the pulley. The replacement process is similar for the critical side’s tensioner, requiring you to remove the included backing plate and screw.

All pulley and tensioner combos above use a special thread-forming screw to mount the pulley to the aluminum base/lever. This screw cuts threads into the aluminum casting and is vibration resistant since there are no gaps between the male and female threads. There is no torque spec for this kind of application, so reinstalling these screws with the new pulley should be done with consideration. When the screw bottoms out against the inner bearing race of the pulley, it should not require much rotation to tighten up.

Lastly, if you have an early production E9X M3 with the original clockwise spinning power steering pump and need to replace it, you’ll have to update your pump to the new style along with the corresponding pulley and belt. While that will be a fairly substantial cost, the good news is the tensioner arm remains the same, and only the pulley needs swapping over, saving you almost $200. We offer a kit to help make that update easier to figure out, which can be found here.

 

BMW E90 M3 Belt Tensioner Assembly & Replacement Pulleys

  • Power steering and A/C compressor tensioner pulley - p/n 11287838196 (Up to 5/15/2008) - Use INA 5320557100 (OE# 059903341G) - 65mm x 26mm
  • Power steering and A/C compressor tensioner pulley - p/n 11287838194 (From 5/15/2008) - Use INA 5320342100 (OE #11281440237) - 70mm x 26mm
  • Alternator and water pump tensioner pulley - p/n 11287841527 (Used on all E9X M3's) - Use INA 5320342100 (OE #11281440237) - 70mm x 26mm

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Written by :
Gareth Foley

Gareth is the BMW Make Level Marketer for FCP Euro and has been with the company since 2012. Gareth's BMW obsession started with a hand me down E39 528i when he was 17. From this car he learned how to do his own repair work while also learning more about BMW. When Gareth was at CCSU studying Marketing he had the opportunity to go to SEMA with the college car club. This is where he developed his love of the automotive industry. Since joining FCP in 2012 Gareth has sought out to develop one of the broadest and most accurate BMW replacement parts catalog. he can be reached at gareth1@fcpeuro.com


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