Tensioner and pulley replacement
Thread Starter
Senior Member
Joined: Nov 2013
Posts: 428
Likes: 63
From: Auburn, GA
C250 2013
Tensioner and pulley replacement
I'm hearing a noise from the belt tensioner. Planning to change the idler pulleys too.
Any advice before I start the work next week?
C250 2013 145k miles.
Any advice before I start the work next week?
C250 2013 145k miles.
Member
Joined: Oct 2024
Posts: 225
Likes: 29
From: Pennsylvania, US
2008 C300 4Matic
Be careful not to overtighten, you’ll crack the aluminum. Smartest thing to do would be to blow the threads out with compressed air before reinstalling but I personally never have done that.
Check your new upper idler pulley very carefully. I replaced mine with an INA and the one I got out of the box was broken a week later, not sure why but I suspect it was damaged in shipping.
Check your new upper idler pulley very carefully. I replaced mine with an INA and the one I got out of the box was broken a week later, not sure why but I suspect it was damaged in shipping.
MBWorld Fanatic!
Joined: Aug 2023
Posts: 3,737
Likes: 1,135
From: MA Coast
W204 2010 C300 4matic Sport M272
Pay close attention when removing the pulleys. On mine there is a washer installed on the lower idler pulley, between the pulley and the engine. Yours may or may not have it.
Follow the torque specs when installing the new parts. Not sure what engine you have. On the M272 there are two torque specs for the lower idler pulley, one for new installation and one for follow-up operations. The new installation is if the water pump is replaced since the pulley is bolted to it.
Save the old belt. I keep my old belt in the trunk just in case the new one ever breaks while driving.
Follow the torque specs when installing the new parts. Not sure what engine you have. On the M272 there are two torque specs for the lower idler pulley, one for new installation and one for follow-up operations. The new installation is if the water pump is replaced since the pulley is bolted to it.
Save the old belt. I keep my old belt in the trunk just in case the new one ever breaks while driving.
MBWorld Fanatic!
Joined: Jun 2014
Posts: 1,086
Likes: 443
From: Melbourne, Australia
2010 ML550 VIN WDC1641722A564750, 2010 B180
Be careful not to overtighten, you’ll crack the aluminum. Smartest thing to do would be to blow the threads out with compressed air before reinstalling but I personally never have done that.
Check your new upper idler pulley very carefully. I replaced mine with an INA and the one I got out of the box was broken a week later, not sure why but I suspect it was damaged in shipping.
Check your new upper idler pulley very carefully. I replaced mine with an INA and the one I got out of the box was broken a week later, not sure why but I suspect it was damaged in shipping.
Out Of Control!!
Joined: Apr 2019
Posts: 11,990
Likes: 6,822
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
NICE AND EASY
Serp + Tens. + Idlers
While you're in there manually check individual accesories pulleys for free play/wobbling.
Double check parts in particular the new belt reference may/may not match your engine.
Lots of poor matches found in belt X-Ref tables.
Your original Ref.# is what works right (+/- half Inch Max).
Parts retailers will set you up with 2 or 3 extra inches... waste of time!
Easy job with quality parts.
Last edited by CaliBenzDriver; Feb 1, 2025 at 03:59 PM.
Thread Starter
Senior Member
Joined: Nov 2013
Posts: 428
Likes: 63
From: Auburn, GA
C250 2013
Thank for all these great advice.
Looked around and found the pulley torque "35 Nm which is 25.8 ft-lb", and for tensioner bolt torque is "25 Nm (18.4 ft-ibs)". can someone confirm this?
This is my Engine no, that means it's a M271 engine?
Engine no.:271860 30 521210
Looked around and found the pulley torque "35 Nm which is 25.8 ft-lb", and for tensioner bolt torque is "25 Nm (18.4 ft-ibs)". can someone confirm this?
This is my Engine no, that means it's a M271 engine?
Engine no.:271860 30 521210
Last edited by meazz1; Feb 1, 2025 at 04:00 PM.
Out Of Control!!
Joined: Apr 2019
Posts: 11,990
Likes: 6,822
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Trending Topics
MB World Stories
The Best of Mercedes & AMG
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)
Verdad Gallardo
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
Member
Joined: Oct 2024
Posts: 225
Likes: 29
From: Pennsylvania, US
2008 C300 4Matic
You’re fine to reuse it unless you’re concerned about it being too rusty or rounded off or anything. The only bolt I replaced was the upper idler pulley and that’s just because it came with one.
Out Of Control!!
Joined: Apr 2019
Posts: 11,990
Likes: 6,822
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
