I have had my mini for about 2 months. I installed a 15% Overdrive pulley I got from Mini Mania a couple of weeks ago and the belt jumped off with in 5 minutes. I pulled the pulley off and reinstalled it thinking it might not have been on the S/C shaft all of the way. Installed a new belt and threw that one off almost as fast. I managed to get it back in the shop to find that the harmonic damper failed. So, I ordered a PRW Fluid damper. I also replaced the tensioner and idler pulleys. As it stands now I am still having issues with the belt coming off. I have looked it over and the pulleys look to be in alignment. It keeps trying to come off on the alternator pulley. I currently have one rib missing from belt. It is on all of the pulleys the same except for the alternator pulley which is off one rib and it hangs a bit off of the idler pulley. I had no issues with the car before I started messing with the S/c pulley. It almost seems like the idler as angled a bit and allowing the belt to walk off. In the picture below I reinstalled the original idler pulley to see if it still walked and it did. As you can see it is one rib in on the alternator pulley and riding off the outside of the idler pulley. Any help would be appreciated.

 

There can be a slight bit of adjustment with the top two alternator bolts, loosen the alternator bolts and see if the alternator can line up better.
It may just have been "close enough" with the other pulley, but the new pulley caused just enough of a miss-alignment.

 

Looking at your pic either the supercharger pulley isn't fully installed and not on far enough.
OR when you did the remove the supercharger shaft was pulled out and now you can't put the pulley on far enough to align it properly. We've actually had 2 cars that shops screwed up like this in the last month and rebuilding/replacing the supercharger is the only correct fix.

 

I will have to try and reinstall the pulley again, it looks like it is all the way on. I can't imagine that the shaft pulled out. I used a Cravenspeed puller to remove the stock pulley, since it pulls on the pulley and pushes off of the shaft it shouldn't have pulled the shaft out any. Thanks for the pointers though.

 

Check all the bolts to all the pulleys to make sure they're torqued down properly.

If that's not it, check the pulley for messed up grooves. I bought a 15% pulley from a member on here last year and one of the grooves was dented over. I can take a picture tonight. I never installed it, but I imagine if I did, then something similar would happen.

Good luck!!

 

Did you ever find the issue? I'm in the SW part of town if you need some help.

 

No, I haven't had a chance to look at it. I had to go out of town on business and wont be back till the end of the month. I also need to clear some space in the garage to have enough room to work on it.

 

Wanted to bring this back up. I've got a buddy who has this same issue. Recently had some service to his engine. Could it be that they overtightened the harmonic pulley throwing the belt alignment off?

 

Overtorqued no, but if the crank pulley isn't bottomed out on the crank then the belt is out of alignment and I have seen that a handful of times.

 

I have messed with it a bit yanked off the 15% pulley from Mini Mania and replaced it with a WMW 17% pulley. The belt started to walk again. Started looking at it closer and noticed that the idler pulley was cocked a bit. The bushing for it was sitting ever so slightly on the shoulder of a bolt that is behind it, you can see where it was hitting the bushing in the picture below. The new Gates idler was the sat the same way as well. With some careful grinding on the bushing we were able to get the pulley to sit square against the block which we though had fixed it. After 30 or so miles it threw the belt off again, this was 2 weeks ago. I haven't had a chance to get under the hood yet to see if we can spot anything else.

 

Wanted to follow up. Tightened the crank pulley down and the belt alignment is good now. The torque value is 85 ft lbs.

Blue, don't know why your alignment is off, but as you have only changed the supercharger pulley that has got to be the issue. As far as the bolt behind the idler pulley, you can remove that and install a new idler. I would try to get everything back to stock. Idler torque is 33 ft lbs.

 

I replaced almost everything. PRW Fluid damper crank pulley, Gates Belt tensioner and Gates idler pulley. I torqued the Crank pulley to 85 ft lbs when I installed the new one. I still havent had time to dig into it again.

 

I had the same issue when I installed my Alta 17% pulley, I did everything you have done, and for some reason when my pulley is installed all the way against the supercharger it would throw the belt. I took it all apart and used my old belt to check to see how the pulley and Harmonic balancer where aligned, and well the where off by enough to see with the belt just around the harmonic balancer and sc pulley. I ended up pulling the supercharger pulley out off the supercharger snout, just enough to align them up. I know there will be allot of people on here that will say that isn’t right, but in my case it was small enough adjustment that the pulley is still secure on the shaft and hasn’t thrown another belt. If you look at this issue I will bet it is the same issue, mine was to far in causing the belt to ride the outside of the supercharger pulley and eventually jump off. Hope this makes since

 

That makes perfect sense and sounds exactly like what is happening to mine.

 

Your experience and discovery certainly make sense. The various reduction pulleys have different design and installation instructions (or the total lack of). I chose a specific brand for a number of reasons, and stay away from some for other reasons such as concern with wear (the AL ones).

 

I looked all over the internet looking for a cure for my issue when mine was doing it, I saw this and had to reply with my fix

 

I have learned this from this POS pulley I have, I am going to make it up to the local mini shop and pick up one of there’s once I get the extra money.

 

Did you fix your issue?

 

No I still don't have it fixed. I had been traveling a lot for work and no time to work on it. I did get out today and start messing with it again and notice the the crank pulley had somehow come loose and walked a bit, it was torqued to 85 Ft-lbs with Loctite so I don't know how that could have happened. I noticed that there is some old belt behind the crank pulley that I need to get out before I torque it again. I have a damper puller but it is too small to fit the PRW damper. I am now trying to find a puller to fit the damper...

 

Go to autozone to rent a puller.

 

That is the plan for tomorrow.

 

name names....what pulley caused the problems for you?

 

I got into it again today, got the Crank Damper off with a rented puller from AZ and found pieces of the old belt back behind and they took out the oil seal. I am now waiting for that to come in tomorrow. The crank pulley I am running is a PRW Fluid Gel Damper. I didn't pre-heat it when I installed it as I didn't have access to an oven at my shop. I think at operating temp it expanded and came loose on the crank a bit and allowed the crank pulley bolt to loosen up even though it was torqued to 85 ft-lbs and had blue Loctite on it. The original S/c pulley I put on was a 15% 3 piece from Mini Mania. After it was installed the stock Damper failed. I then ordered the PRW damper, Gates Tensioner and Idlers, then had another failure. So off came the 15% and I installed a 17% from WMW. It was good for about 30 miles when the belt came off this time.

Here is the belt that was behind the crank pulley.


Here is the oils seal that will be replaced tomorrow and will reinstall the crank pulley.

 

We all appreciate that you share your experience of the mishaps. A lot of folks would not. We all make mistakes.

 

Well I got the new seal this afternoon, got it installed. Heated up the pulley in the oven before hand. Installed it back on the car. Reinstalled the bolt, I didn't have loctite at the time. Torqued the bolt to 85 ft-lbs. Took the car to Autozone for some loctite and a short drive of a total of 5 miles. Got home, popped the hood and found the bolt loose enough to remove by hand. Took it out and heavily applied the loctite to it and re-torqued it to 85 ft-lbs and plan to leave it be for 24 hours. I also ordered a new bolt from Way Motor Works just now since they are recommended by Mini to be replaced when ever they are removed.

It was a lot of fun ripping on it for 5 miles...