Serpentine belt needs to be replaced due to noticeable cracks. When the car is idling, I could also hear a light squeal as if it's coming from one of the pulleys. There is 133k on the odometer and I'm pretty confident the pulleys have never been replaced before. Usually when replacing the drive belt what pulley would be recommended replacing as a precautionary measure even if it's not making any noises?
All, if they have 133k on them...no better time to do them if you already have the fan clutch and belts off.
In addition to replacing the 2 pulleys, I would highly recommend replacing the two little shock absorbers - one on each pulley when doing the job. Fairly easy job to do, and just as easy to replace everything while in there.
CSi #18 - Car & Driver Magazine 1994 actual test car
-- Hellrot/Black-Gray (1 of 1 NA CSi color combination)
BMWCCA E31 Chapter International Clubs Liaison
North America Representative, 8er.or Board of Directors
I discovered the belt to be worn while replacing the fan clutch. I will have to again remove the clutch and fan to replace the belt and pulley. I'm going to purchase a contitech belt off ebay, as well as those $15 a piece idler pulleys. Still trying to get a hold of the spring damper as people are recommending that I replace that too.
When you go to tighten the belts, remember to set the adjuster to the end stop. The little shock absorbers will take up the slack. If the belt is too loose, it will make noise and possibly wear out much faster.
'93 850Ci - Mineralweiß Metallic
2001 740iL - Titansilber
ALPINA B7 -Alpinweiß III
...the price of cool ain't cheap!
fXOCL5qgkW.jpg
Are the two pulleys "D" identical? 80mm, correct?
No. lower one is smaller, 70 mm
850's are identical
840's are not
'93 850Ci - Mineralweiß Metallic
2001 740iL - Titansilber
ALPINA B7 -Alpinweiß III
...the price of cool ain't cheap!
I recently changed the belts on my m70, i noticed that the new belt i bought was a bit shorter and wouldnt allow the tensioners to work properly. Make sure to compair old with new belt for lenght. Also you dont have to take fan off to change belts, i snaked it through fan blades.
AutohausAZ is your friend.
For the 840ci, these should be the part numbers you need for the belt and pulley replacement.
FCPEURO
BMW AC Drive Belt - Contitech 5PK980
BMW Drive Belt Idler Pulley (80mm) - INA OEM 11281731838
BMW Accessory Belt Idler Pulley (70mm) - INA 11281731220
I actually just ordered all this stuff to do my belts and pulleys as well. One of my pulleys (the one closest to you when looking at the engine) seems to have a chunk missing out of it... and I get squeal when the engine is cold.
Combination of ordering from ECS Tuning (free shipping to my cousing) and FCPEuro (cheap shipping to me in Australia, didn't have belt in stock) made my choices easier. I went with INA (OEM) pulleys, genuine BMW water pump pulley and ContiTech belt.
I just removed the fan clutch to check/set cam timing. I thought I would replace the belts, tensioners (2), and idler pulleys (2). I did not see just the pulley only identified on realoem until I found this thread and part number. So it looks like its cheaper to replace just the pulley and not the complete assembly. Looks like FCP has these pulleys available.
Not sure which belts are correct for my car? I dont think there is an additional alternator, well, I dont see one on the engine.
Looks like OEM belt for alt is 11281736719 and accessory belt is 11281733708. Are the Contitech belts of good quality and correct fit? They sure are a lot cheaper than OEM.
Last edited by JDP530; 10-30-2017 at 08:54 PM.
Here is a 75mm Ina replacement pulley but I haven't found any other dimensions to determine if it could be used for a replacement on the M70 engine tensioner. I have found these as cheap as $25 on another site.
BMW Drive Belt Idler Pulley (75 mm) - INA 11287578674
135i, 335i, 335i xDrive, X1
Part #: INA-5320751100
I use FCP Euro for a lot of parts for my BMW, Audi, and MB (and departed Porsche 928's). The Conti belt they list is not one I'd buy. I'm a very strong proponent of Gates belts. In the 928 community, the timing belt is VERY long (longest ever produced when the cars were introduced). There, we had a lot of complications as the Continental belts were stretching in a short time (20K miles vs the normal 50-60K mile replacement cycle) and the OE tensioner would no longer provide the specified tension. Gates belts (like the OE Porsche belts) did not seem to stretch for the duration of usage.
Just my experience.
Gary
Last edited by Gary Knox; 11-01-2017 at 01:41 PM.
Gary Knox
'97 BMW 840 Ci
'03 MB SL55 AMG
'07 Mini Cooper S hatchback
'09 Aston Martin DB9 Volante
'13 Audi A8
'90 MB 560 SEC and '94 Porsche 928 GTS recently departed but long enjoyed
50 or so others over the past 70 years of driving
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