M271 E200 W211 Belt Tensioner Replacement

[Kompressor_Dude]

Searched the forum and can’t find anything on this. I have the apparently common issue of cold start rattling. Idler pulleys both replaced and other pulleys all spinning smooth and free.


I left the tensioner first time round though and it’s still making the noise. The belt is flapping around a bit so seems loose. No avoiding this job now…

The tensioner unit is bolted through from the other side of the engine. I’ve moved the steering rack and some lines, but access is still absolutely ridiculous!

While I’m busy wishing the engineer responsible steps on a Lego, can anyone who’s done this job before help me with any tips on access or tools that make this possible?

 

[Kompressor_Dude]

Decided to go in the top. Possibly more work but I was getting really frustrated with access from underneath.

Removal of the airbox, intercooler, intake and supercharge gives great access….



The old tensioner has slipped plastic insert so am hoping this is what’s needed to resolve the issue.

Just got to put it all back now but want to research ‘while I’m in here’ jobs as lots of plastic and rubber that would be cheap to do now and a pain to come back for in a few months.

Suggestions welcome!

 

[Kompressor_Dude]

I’ll continue with my findings in case this helps anyone if the future. Turns out there’s a well-known breather hose and check-valve setup on the block that perish. My hose was split so I’ll replace the lot. Hadn’t noticed a rough idle but maybe it’ll run better now. Picture below.

Will also replace the inlet gaskets as they are so cheap It’s silly not to having gotten in this deep. The only other thing I found was a check-valve attached to the supercharger that passed air each direction so needs replacing.

Pretty cheap as far as the ‘while I’m in there’ repair tax goes.

 

[ALFAitalia]

Wow.....there must be an easier way!!!

 

[AMGeed]

^+1.

DIY: M271 Idler & tensioner pulley - MBWorld.org Forums

C-Class (W203) - DIY: M271 Idler & tensioner pulley - Tools: T-50 torx T-60 torx E-12 socket Flathead screwdriver Flex head Short extension 1/2 ratchet 3/8 ratchet Parts: 271 200 05 70 (Tensioner Pulley) 271 206 00 19 (Idler Pulley) I've seen a few DIYs on this topic before, but none of them has...

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[Kompressor_Dude]

Just finished up and had a test drive…. with no noise!!! It worked

If there is an easier way then I hope it gets posted for the next person as that wasn’t a particularly fun job.

Ended up replacing the breather assembly on the block and a few broken check-valves. New inlet gaskets and obvs new tensioner. That’s just over £150 of kit in total and a pretty good overhaul of some hard-to-reach parts done all at once.

I found this thread very helpful:

m271 Belt tensioner replacement - MBWorld.org Forums

C-Class (W203) - m271 Belt tensioner replacement - I have been looking everywhere for a D.I.Y thread for a replacement for a belt tensioner but I only found information about replacing the pulley , so I decided to make one. Tools you will need Torx Socket set E-Torx socket set Breaker Bar A long...

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