E9X M3 S65 Ultimate Belt/Pulley/Tensioner Guide :)

There's several threads on this but none of them I found seem to have all the information about OE equivalents to the VERY expensive belts/pulleys for these cars so here is all that information aggregated into one post. Please note that if you're installing these components yourself to REPLICATE the exact setup that was originally installed on your car, specifically in relation to the bolts, pulley covers, or heat shields. For example, if the pulley comes with a bolt but it's different than whats on your car right now, use the original bolt from your car, not the new one.

You can find your production date using a VIN decoder like mdecoder.com
Before 4/29/08: clockwise-rotating power steering pump
On or after 4/29/09: counterclockwise-rotating power steering pump

RealOEM Full Parts Lists:
- AC / Power Steering Pump Belt: https://www.realoem.com/bmw/enUS/showparts?id=WD93-USA-01-2008-E92-BMW-M3&diagId=11_4120
- Water Pump / Alternator Belt: https://www.realoem.com/bmw/enUS/showparts?id=WD93-USA-01-2008-E92-BMW-M3&diagId=11_4119

Air Conditioning and Power Steering Belt


If your M3 has a production date BEFORE 4/29/08:
#1: AC / Power Steering Serpentine Belt
- Continental 6K1065 or Gates K060420 (Replaces: BMW 11287838200)
#2: AC / PS Belt Tensioner Pulley
- INA 5320557100 / FP05571 (Replaces pulley on: BMW 11287838196)
#3: AC / PS Belt Tensioner Strut
- BMW 11287835422 (There is an INA PN, but it doesn't seem to be purchasable.)
- BMW/INA 11281709613 (Part from M62TU motor that is same size and fits our cars!)
#6: AC / PS Belt Deflection / Idler Pulley
- INA 5320418100 / FP04181 (Replaces: BMW 11287841228)

If your M3 has a production date ON OR AFTER 4/29/08:
#1: AC / Power Steering Serpentine Belt
- Continental 6DPK1100 (Replaces: BMW 11287841529)
#2: AC / PS Belt Tensioner Pulley
- INA 5320557100 / FP05571 (Replaces pulley on: BMW 11287841527) (E60 M5 version: INA 531 0760 10)
#3: AC / PS Belt Tensioner Strut
- BMW 11287841546 (There is an INA PN: INA F-239109.01, but it doesn't seem to be purchasable.)
- BMW/INA 11281709613 (Part from M62TU motor that is same size and fits our cars!)
#6: AC / PS Belt Deflection / Idler Pulley
- INA 5320515100 / FP05151 (Replaces: BMW 11287841531)

Alternator and Water Pump Belt


All production dates:
#1: Alternator / Water Pump Serpentine Belt
- Continental 6K1460 (Replaces: BMW 11287837898)
#2: Alternator / Water Pump Belt Tensioner Pulley
- INA 5320342100 / FP03421 (Replaces pulley on: BMW 11287838194)
#3: Alternator / Water Pump Belt Tensioner Strut
- BMW 11287835417 (There is an INA PN: INA F-239110.04, but it doesn't seem to be purchasable.)
- BMW/INA 11281709613 (Part from M62TU motor that is same size and fits our cars!)


Sources:
Theodore's great OE equivalent thread: https://www.m3post.com/forums/showpost.php?p=21123800&postcount=1
Lots of googling

I'm a little confused. Is the pulley itself on the tensioner arm (AC & Power steering) different between the two production dates? I'm having trouble fitting the double sided belt on my 2010 M3 and have been running the single sided belt since I can actually get it on there. I did replace the tensioner pulley with a used one because mine snapped off. I ordered one on eBay for cheap just labeled as "E9X M3" with no specific year. I'm now wondering if its a different part number and that's why I can't get the double sided belt on. Its as if the pulley is just slightly too big.

Can anyone confirm which production years use the 65 vs 70 mm pulley for the AC/Steering side. This thread suggest the "later" years use the 70 mm pulley as does this quote from FCP euro

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

However, I've seen some older post of those actually performing this before all this information was available stating it's the opposite. The early 08's used 70 mm and the later production was 65mm. Plus there is a review on FCP euro about it being wrong as well. About to start tackling this today, and ordered the FCP euro guided 70 mm pulley. Hate to waste half the time getting down there and it's the wrong side. Thanks

2007 production car has 70mm A/C+P/S pulley, like ALT side.
I ordered 65mm + 70mm pulleys, replaced 70mm and 80mm idler. After that some time later restored all three old pulleys and put them back. Just out of curiosity. Old pulleys weren't worn out actually, just grease was dryed. Put some new grease and high viscosity LSD oil, now they work like a charm.

New pulleys make the S65 pur so smoothly and quiet.

Under rated maintenance item.

nick3753 wrote

Can anyone confirm which production years use the 65 vs 70 mm pulley for the AC/Steering side. This thread suggest the "later" years use the 70 mm pulley as does this quote from FCP euro

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

However, I've seen some older post of those actually performing this before all this information was available stating it's the opposite. The early 08's used 70 mm and the later production was 65mm. Plus there is a review on FCP euro about it being wrong as well. About to start tackling this today, and ordered the FCP euro guided 70 mm pulley. Hate to waste half the time getting down there and it's the wrong side. Thanks

Hi Nick, how'd you go with this one?
I just ordered the pulleys to replace on my 08 e92 M3. Based on the FCP article I ordered the "earlier production model" and received a 65mm diameter pulley but the one pulled off my car is 70mm diameter idler pulley.

I have double checked my car's build date, it has a compliance date of 2nd April 2008 and build commenced in January 2008. So safe to say it is the 'earlier' production (pre 15/5/2008).

Keen to know even if anyone else has any insight to confirm which is correct.

I ordered the 65mm pulley. FCP (and OP) has it wrong. I haven’t gotten around to installing yet, but was able to measure the existing pulley while still on the car and confirmed it is 65mm for my 2012.

Thanks Nick, will need to order another now and fork out the extra $50USD for postage unfortunately
On the up side I have an expensive paper weight now for the desk

MIK3_S65B40 wrote

Thanks Nick, will need to order another now and fork out the extra $50USD for postage unfortunately
On the up side I have an expensive paper weight now for the desk

Well, hopefully you have better luck than I had. Tackled the job this weekend (including OFHG). Not only did I manage to break the upper radiator hose nipple removing the fan, but my ac/power steering pulley bolt was siezed to the metal lever part. I got it off, but it messed up the threads. When I went to install the new 65mm pulley it just kept turning and would never tighten properly. Now I have to order the $200 part, plus the money I spent on the wrong pulley (thanks FCP euro) and the one I attempted to install today. I may see if I can return them for at least store credit. 🤬🤬

As an update:
I contacted FCP and they have updated that blog post with the correct information. Whether or not they changed the links and description for the replacement pulleys I am not sure of. 65mm for later production years and 70mm for early (AC/PS side).

I have a 2010 M3 and the AC/PowerSteering belt refuses to go on. I can't figure out as to why, I have a new double sided continental belt for it but its just slightly too small to fit around all the pulleys.
tensioner pulley I have is FP05571
I have been running single sided belts because they will actually fit. They wear out fast obviously because its not the right belt, every now and then I try to get the double sided to fit but it just never does and its really starting to become infuriating. I have the belt fully on with the last bit needing to go around the tensioner itself.

I have used a high lift jack handle as a breaker bar, it will fully move the tensioner to it most open position before the bolt holding the pulley itself to the arm starts to spin. I am worried I will over tighten the bolt to the point where it will snap (again). Any suggestions? maybe red thread locker on the bolt that holds the pulley to the arm?

I used a long offset box end wrench for mine and did feel like I was going to tighten the bolt more. But I managed to get it on. Tight fit for sure.

I should add that I am running UD pulley set (PO’s choice, not mine) so maybe that’s why I didn’t struggle as much?

It's tight, but you should be able to get the belt on as long as you are bottoming out the tensioner. A long handle belt tool or ratchet will help, make sure it's not hitting anything that is stopping you from bottoming out the tensioner.

You have to make sure the belt is seated around the pulleys and positioned to just slip over the tensioner pulley, if that doesn't work try slipping it on the AC pulley.

Oreo Cat wrote

I have used a high lift jack handle as a breaker bar, it will fully move the tensioner to it most open position before the bolt holding the pulley itself to the arm starts to spin. I am worried I will over tighten the bolt to the point where it will snap (again). Any suggestions? maybe red thread locker on the bolt that holds the pulley to the arm?

Are you certain you are using the correct belt path for the year of your car?

DrFerry wrote

Are you certain you are using the correct belt path for the year of your car?

I don’t have the original package for the belt, so sadly I don’t have the part number. I got it as e9x m3 belt and it’s double sided. But I have decided I am going to get one from the dealer, and if it doesn’t fit then I will return it and try to figure something else out

https://www.turnermotorsport.com/p-361079-air-conditioning-drive-belt/
I think I’m going to try this belt because I work when the dealer is open and it’s an hour away
Any thoughts?

Oreo Cat wrote

https://www.turnermotorsport.com/p-361079-air-conditioning-drive-belt/
I think I’m going to try this belt because I work when the dealer is open and it’s an hour away. Any thoughts?

Yes, I came up with the same part number =11287841529. Your 2010 M3 has a counterclockwise power steering pump. See all images attached.
.

new belt is on it way, I will feel like an idiot if I was trying to use the wrong belt all along but still the best outcome. hopefully it shows up before the new year

New belt is here. Same problem. I can’t move the tensioner any farther down without breaking it

Spray that bastard down with window cleaner and slide it on.

Holy crap it’s on. Took a high lift jack handle as a breaker bar and a screwdriver to get it all together but it’s on. Car must have known I was about to throw the high lift jack handle through the windshield.
Thanks to everyone who helped
For future people who might read this - yes it’s that much a pain to get the belt on. I’ve had 2 bmw 335is, I’m in my second e90 m3, i have a Tacoma that I’ve changed out the engine on, a few Honda cars I’ve worked on.
This was one of the most infuriating car things I’ve ever done, but it is possible.