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I am going to replace my alternator on a 2003 C320. The belts are the only thing that seems really weird to me. I have worked on BMW's, SAABS and older Mercedes (primarily old diesels).

I am confident about everything but the belts. I've never seen such a setup as on this car. On the pully's there are caps w/ 3-4 bolts on them, I don't have a picture to post, but I am sure someone knows what I am talking about. Are these used to adjust the belts ? I am confused as all hell about these belts I was hoping a fellow DIY'r could give me a quick run-down (w/ pictures would rock) of how to losen the belts so that I can remove the alternator from the car sucessfully. I want to be sure I do not open a rats nest by doing something I either do not have to do or doing something wrong all together. Any help would be really really helpful. Thanks again in advance!

-mbc320diy
 

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2002 C230 Sport Coup and 2006 ML350
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You need an inverted torx socket, I forget what size, just buy a set if you haven't already.
Look at the belt, locate the tensioner pulley, it has a torx head bolt sticking out the front.
Put the wrench on the front of the tensioner, pull to the left, the pulley will move to the left.
Pop the belt off while hold the tensioner.
You can do it youself, but it helps to have an extra hand.

The owners manual has a diagram of the belt routing.
Be sure to get it right on the way back,
and watch your fingers.

Also, get a socket for the crank, I think it's 27mm...
turn by hand to make sure everything is lined up good, and not binding.
Then watch it when you start it, make sure it's good, and then...you're good.
Make sure you line up the belt correctly on all pullies.
 

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Discussion Starter #3
C230SpotCoupe,

Thank you so much for responding and, lending a helping hand. I really needed to finish the job quickly, so I have a working car. Thanks to you, it helped make that possible! I took pictures, so I will put together a DIY guide for replacing an alternator + belt.

Thanks again for all the help !

-mbc320diy
1961 190 - 1962 LR Series II - 1978 240D - 2003 C320 4Matic - 2004 BMW 325Xi
 

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Tensioner Pulley

I began to tweak (what I thought was) the tensioner pulley, but the bolt just started to come off... I have seen other tensioners simply pivot when applying pressure, but when the bolt began to loosen, I stopped and checked in here... either that is NOT the tensioner, or something is off... here investigating before I pop a pulley off...
 

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Here's a photograph of what the tensioner looks like. Should look the same on m271 I assume... One for each belt track of course. Other one is located on the left side. Not very visible in this photograph.
 

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Moneygrabbers

I dug around and found it was the pulley below the one I thought... Yours is a tad different, as mine requires a TAMPER PROOF torx bit. I guess too many people were buying regular widely-available torx bits, they decided a widely-available tamper proof torx bit was the way to go.

It's completely perplexing some of the decisions MB makes.
 

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2002 C230 Sport Coup and 2006 ML350
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I did a water pump on a 3.2L...just a plain inverted torx...it was a 1999 model though...
there's a plastic cover on the front of the tensioner, and nut holding the pulley to the tensioner, and then 3 or 4 bolts holding the tensioner to the front of the engine,
just a little addtl. info FYI.
PS. Doing a water pump on a 3.2L = Royal PIA.
 

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Did the water pump on my 2.3lt m111, and it was very easy. What made the 3.2L a pain? I assume the location...
 

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Did the water pump on my 2.3lt m111, and it was very easy. What made the 3.2L a pain? I assume the location...
You need to remove everything...the alternator, belts, all the pullies,
and theres about 40 bolts all different lengths.
On the suggestion of the local mechanic I made a template from
carboard from the new pump, and put the bolts in the template.
The ML had a fan attached also that requires removing the fan with special tools, which I was lucky to be able to borrow.
I saved her 350 but I see why it cost that.
Biggest job to date on a benz, and that includes everything I've done.
Nothing else was this much work!

It's like everything bolts to the water pump. So many bolts!!! Unbelievable.
And so many different sizes. Constantly changing sockets.
 
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