Hello wondered if anyone else has suffered from drive belt issues.
I've been through three now in 18months. I have changed all the plastic pulleys to new ones and the tensioner is new, 3 different make belts also.

I do hardly any miles, around 3k per year. The first snap was the top idler pulley, but that was changed after, second time I did all the rest and the tensioner, but yesterday snapped again, lasted 8 months this time, can't see any problems with the pulleys this either!.

Air con works and power steering doesn't seem seized either.
Is it best to just go Billet ones?
Always seems to take out a water pipe or something when the belts snap

What retailer did you buy belts and pulleys from?

the factory issued belt should last many years...and by many, i mean it. i would confirm you have all your engine accessories as being bolted tightly. the power steering pump should also have a bracket behind it to prevent it from wobbling. also you can check the alignment of your pulley's using a laser tool for pulley alignment.

something is causing the issue, we'll just need to narrow it down to identify the true cause.

your original post is a bit all over the place. the factory pulleys last anywhere between 1-5 years. they can fail closer to the 1 year mark if you drive your car hard. aluminum pulley's from what i've seen are assembled with subpar bearings and you'll run into bearing failure issues in time. they'll need to be swapped out for higher quality bearings if you go the aluminum pulley route.

Had this issue as well. Second time it happened, top pulley disintegrated for me. Replaced w/ billet but havent put too miles on it yet to see how the belt is

If there isn't an offset or defect within the pullies/tensioner causing it to walk off there's a good chance the belt is subjected to a leak/debris. Triple check belt routing and replace any shot motor mounts. By fortune the belt has not snagged the AC connector "yet"

I'm running UPD billet pulleys and Gates RPM High Performance belt. They're supposedly much stronger and meant for racing applications.

Buy OEM parts from the dealer.

I have Gates, Continental and Dayco belts all snapped.

All pulleys were Febi and the new tensioner was Gates.
I will have a look at the power steering bit, as I did have that undone when the first belt snapped and took the thermostat pipe out

I might look at those stronger gates ones now though
When running all pulley look straight but only to the eye

Did I read somewhere that the crank pulley can be changed to a revised one? My is a 2008 model

Buy OEM parts from the dealer, for everything but the simplest items. Never buy aftermarket electric parts.

Do not buy aftermarket belts, hoses or pulleys for these cars.

I doubt a Mercedes belt is any different to any other to be honest, it's probably made by one of the above in any case or Goodyear.
I have also had Febi parts supplied to me from the main dealer

Never buy any belts but OEM

does your car have the idler pulley between the a/c compressor and the crankshaft pulley? this helps with belt alignment and keeping tension present

I always run continental belts, never had any issues.
Also Febi Bilstein is an OEM supplier to mercedes, maybe not the pulleys but other parts.
And as Febi has qualified as an oem supplier i figure their pulleys are just fine.(i have a complete kit on mine, no issues)

Check your powersteering pump, if it making a loud whine it might be on it´s way, and by that making life hard for the belt.

Thanks, I have noticed a drone now and again from the power steering pump.

Agreed Febi are good quality, lots of dealers now supply Febi as OEM, you get Febi parts alot cheaper from your local motor factors rather than been ripped off from the dealer

What if you don't have a choice?