So I will start at the beginning....

I was driving back to the office from a customer who wanted to ask some questions about their coverage (insurance, if anyone needs good/cheap insurance let me know ) and my 2006 r53 went into limp mode. I made it to the office, as I was only a block away. On the way there I noticed a rise in temperature, but did not let it go very far before letting it cool down. My initial thoughts were that I threw the belt. I look and the belt was still intact. I did some more diagnosing and whenever I turn on my AC the belt stops. So then my thoughts were compressor seizing. I went ahead a looked around a bit more...damper seems to be in good shape, pulleys all rotating with ease, so I went ahead and put a new belt on thinking that maybe the old was just,well... old. Put the new belt on and at the supercharger pulley it seems to be jumping threads from front to back. Also, sometimes when I start the car I get a ticking noise and the tensioner clicks and bounces. It also has a bearing grind sound to it. It seems as though it's moving more than it should, but only once and not repeatedly.So here lies the problem... I am pretty lost on this one. I would hate to have to spend copious amounts of money on a new compressor or belt tensioner to find out it wasn't either. So here are some questions:

Whenever the belt is off, if I were to try to spin the compressor clutch, while disengaged, by hand should it move with ease? Mine seems to have resistance. I am not sure if it should or not as I haven't dealt with ac on cars.

Is there a way to test the belt tensioner to make sure that it has appropriate tension? I know that I can use the serpentine belt tool and play guessing games, but I am looking for something more accurate.

I travel a lot so I would like to get the mini back on the road asap. I know this is a lot to read, but I could really use some help on this one.

06 R53 118K, Bought used so I don't know all the service records.

 

The belt tensioner is only $84 and does wear out over time

Since you already have the belt tool I would start with this.

 

What your describing is actually a crank pulley failure. Pretty common as the rubber in them drys out and cracks and breaks. Then when you drive and add the extra load of the A/C it won't turn everything.

Perfect chance to replace the crank pulley with the ATI damper as it will not break again like the OEM, and work better and smoother.
http://www.waymotorworks.com/super-d...ulley-r53.html

 

Same issues with my son's car and I spent a bunch of money doing preventive maintenance and necessary repairs on his 2006 Cooper S. I bought OEM parts for everything such as timing guides, chain, gaskets, tensioner, belts, bolts.....except I went cheap on the crank pulley/damper. I bought a cheap one from ebay for $80. LOL, a big mistake. 3 months later and about 7k miles, the damper fell apart! The metal cracked! It has a 12 month warranty, but there was no way I was going to put another one of those in and the only place it belonged was in the trash can. I would strongly recommend you buy an ATI pulley/damper and be done with it.