can anyone tell me which pulley is the belt tensioner on the m271 or 2003 c230k c-coupe?

the manual doesn't indicate which one it is. it describes a guide pulley and an idler pulley, but not the tensioner.

thanks.

nevermind, found it. it's labeled as the idler pulley in the manual. it's below the s/c pulley to the left, directly below the guide pulley, which is to the top-left of the s/c pulley. it takes a security torx bit to pull it back. haven't figured out what size yet, or where to get one.

this is specific to the '03 c230k c-coupe. i don't know how this configuration applies to others.

in other, related news, i have a rant brewing about this forum as well as benzworld. searching who knows how many keywords, dozens of threads about replacing alt, tensioner pulleys, misc. pulleys, "the dealer fixed it!" etc. etc. and not a single mention of:
1. which pulley is the tensioner pulley
and
2. that it takes a security torx bit

ugh...

Hey - Now you have enlightened the entire forum!!!! Remember to post the size of the Torx driver & where you found it. Then copy & paste to Benzworld and enlighten them

ok, so the security torx bolt (t50) on the pulley is to loosen and remove the pulley itself, not to release the tension.

there's a spot just below and to the left of the tensioner pulley, for a t60 (regular torx). use that.

again, this is on the m271, on an '03 c230k c-coupe.

Great!

Just had the tentioner pully replaced, twice, by the dealer.

When your car's under warranty why get your hands dirty?

Yeah. I don't anyway. I learned at 16 I'd rather pay someone to do that kind of work.

Bustin' my knuckles on my 1961 MGA 1600 mkII. Loved driving it, hated working on it.

well, this car is out of warranty.

and once again i learn that the dealer can't be trusted. a week after taking care of this, the car started acting up. lost power (supercharger bypassed) and CEL.

it turns out the intake piping running into the throttle body came loose enough to cause issues. why? when we took the car in for that recall, they used zip ties instead of the proper metal clamp on that pipe. and they expected that to hold? ugh. and so they lost the original metal clamp on there. so what else did they lose? ugh x 2.