so here's the story I got off work for lunch my car has been parked at this point for about 5 hours I turn the car on the AC was started at low I got about a block away from workto the light and I accelerated from the stop position I got to about 5 to 10 miles an hour in the car jolted and when apparently into limp mode the battery light came on a couple other lights came on the service engine light came on I drove about a half a block pulled over turn the car off had it towed to my house once the car got to my houseI took the front right wheel off and took that wheel well housing off and turned the car on so I can see the serpentine belt I was noticed the serpentine belt was still spinning as my dad got in the car and press the gas the belt wOuld spin but I noticed the supercharger pulley would spin but when the RPM's would get high it the s/c pulley would stop spinning for a split second the rpms come down again and it would start spinning again I don't understand what this problem is if I have a bad supercharger or if the supercharger pulley Has gone bad I know when I pulled the car over it had a little bit of a burning rubber smell nothing major but I can definitely smell the burning smell I also noticed that when the car was turned on and in limp mode it had a little bit of a rough idle so I shut the car off please help also now when I turn the car on it sounds like there is a louder rattle coming from the supercharger pulley area than normal

 

Sounds like your crank pulley has died. Common problem. Replace with an ATI Damper from WayMotorWorks.

 

I agree with above, check your crank pulley. OEM is not of the best quality..

 

Agree on the crank pulley, mine rattled when it got real loose. It was banging against the crank case, also get a new crank seal and belt tensioner.

 

I would also guess the crank pulley.
Instead of replacing with OEM, I installed 2% ATI pulley from WayMotorWorks.

 

Ok but y would the s/c pulley stop and go at hi and low rpms if it has to do with the crank pulley? I'm just wanting to better understand my car and the problem it has. Thanks guys

 

The belt connects the crank pulley to the supercharger pulley. When the crank pulley breaks (separates) the belt intermittently stops turning thus the supercharger stops turning. There is a rubber isolator on the crank pulley that cracks allowing the outer ring of the crank pulley to be separated from the crankshaft that turns the belt.

 

Ok great ty! I can see the crank pulley and it appears to be completely spinning like usual. .. is this normal if it has failed?

 

Look at the rubber between the two metal parts....
It separates from the metal...and slips... Grips when cold or low load situations....gradually It worsens...
The issue is....when it slips, everything runs slower or stops that are attached to it....the water pump is run off the sc...and the alternator And ac run directly off the belt....
If only the sc was slipping...the alternator and ac would function normally.....but car would run hot with low power....you battery light turned on when the slipping was happened....so this is not happening...
Waymotorworks has a picture of a few failed crank dampers on the site where they sell the ATI and PRW branded replacements....some tear some just slip...
very common failure.... Simply due to the OEM design...rubber, heat, corrosion and tourqe...it is only a matter of time....the ati and prw branded ones have a different design....more $$ to make, but longer lasting.

 

Sometimes you won't be able to tell until you really get in there, this is what mine looked like 2 months ago when I pulled it:

 

also I wanted to Note and it sounds like the gentleman in a previous post also had the same type of idea that makes sense with what I'm about to say the AC was not working as I turn the car on and including after the car went into limp mode and came to a crawl. I am just glad it doesn't sound like the supercharger has blown or is malfunctioning.thank you to all you guys who replied I appreciate the input and it is very useful thank you

 

so I did the work myself on the mini tOk everything off and I finally got the factory crank pulley removed and sure enough the rubber inside was destroyed and broke so I put a m7 4% pulley on there and put everything back together correctly of course and the car now has a sound almost like when someone has bad brakes and it kinda sounds like its grinding on the rotors not quite as bad but when I give it high RPMs the sound gets a little bit louder and more pronounced I don't know if it's coming from the supercharger pulley or if it's coming from the idler pulley.I just bought this car a week ago its a 2006 and only has 54,000 miles I don't no why I am having these problems I just hope I didn't buy a lemon very nervous right nowI plan on listening with a stethoscope to the engine components to try and diagnose what is going on with this Mini Cooper any input is greatly appreciated as always

 

Glad you resolved the crank pulley issue. Make sure the crank pulley seated properly and the belt is aligned properly with all the other pulleys so that the belt is riding correctly (nice and straight) at each pulley.
Yes, try to isolate the noise.
While the crank pulley was bad it might have stressed another pulley bearing or bushing. I would suspect the belt tensioner and/or bushing (just rubber bushings). If you need tensioner bushings you can upgrade to polyurethane (check one of the vendors such as WMW or ECS Tuning). I got mine from WMW.

 

4%? Possible the pulley doesn't fit right and is rubbing on the block? Possibly overspinning something? Grinding noises are not good to have on a motor, obviously.

I run a stock size ATI fluidampr pulley from RMW on a built motor, no issues.

 

I also use the ATI pulley. I went with 2% from WMW. I think a little dampening on the crank pulley is a good thing and decided against a solid crank pulley.

 

Post a sound clip

 

Something does not sound right....
Did you follow the instructions....
The new crank pulley usually has to heated....it is an interferece fit...no keyway...usually a NEW bolt that is torqued....
Sounds like it might be slipping...on the crankshaft...destroying the end...requiring a $$$$$ rebuild or motor swap....
A 4%!!!!!
You gonna over speed you alternator and ac by a HUGE AMOUNT?!
2% is OK....boarder line OK..but works... 4% ouch!! I would not try it....
And one tip...the new owners of m7 (about a year) know less about mini's than you...so be careful....

 

4% should only be on a race car, if that. Did you change the supercharger pulley as well? If so what size is that? If you did, hopefully you have a good upgraded intercooler and meth injection to keep her cool. Also 4% would require a different alternator pulley to keep it from over spinning.

 

With a 2% crank...the alternator and ac pullies are kinda OK for most...
But with a 4% WOW!! bet you might burn out the entire electrical system...overcharging...and kill you ac compressor....
Checked m7 website....they somehow infer THEIR undamped crank pulley is the only one that will not slip or hurt you car...lol...
PS...I have the ATI....
NO ISSUES....car...just has to be installed right...SAME METHOD as the m7...lol.
My car actually idles smoother with the ati unit...so the dampening DOES do something...fact the OEM spent $$$ on putting a damped pulley on every car sold rather than the cheap solid one says it all.

 

Not an expert, but I figured if the engineer's who designed my MINI wanted a crankshaft damper I wasn't about to second guess them. My car runs an ATI damper too & like Zippy it feels like it has smoothed out my engine too.