How easy or hard should it be to turn a JCW super charger by hand? My 04 Cooper S with dealer installed JCW tuning kit and new super charger and water pump installed by the PO in 2017 with an Alta 17% pulley has resistance to turning but can be turned by hand or by an Allen wrench inserted in one of the three Allen socket head cap screws, but it has some “stiction” and moves in 1 or 2 degree steps as a small force is applied to the end of the Allen wrench. It definitely does not spin freely and I assume this is from the vanes being in close contact with the inside of the body. Should it “spin” or is this a normal resistance?

I ask because I am trying to determine the source of an increased mechanical noise from the right side of the engine that has a new belt tensioner & belt, a freshly rebuilt ATI super damper, and other components that seem to be OK including the alternator, idler pulley, and AC clutch pulley. There is about a 10 dB increase in engine noise, (measured near the right side of the intercooler manifold and the pivot end of the belt tensioner), from running at idle without the belt to running at idle with the belt on and all the components spinning (AC off). I had noticed an increase in mechanical noise shortly before the tensioner broke into pieces, the belt was shredded, and the damper was trashed at 70 MPH on the highway, and even with the new components the “extra” noise is still there and may even be louder than before the implode.

 

start the car up with the belt off that will let you know quickly if it's an accessory like the supercharger causing the increase in noise. I use a stethoscope with a metal rod on the end to verify which bearing is getting loud they sell these at most auto parts stores

 

Thanks for the reply. I have done the stethoscope and listening without the belt And have not found the cause. From my notes: "I started the engine and listened with my mechanics stethoscope; The belt tensioner was vibrating quite a bit. The loudest stethoscope sound comes from the pivot end of the belt tensioner and then the bolt on the tensioner idler pulley (about equal) followed by right manifold on the intercooler (A little less), and the body of the super charger (about the same as the manifold). The flat idler pulley bolt and the alternator body were much quieter (about equal in sound level), and the AC clutch (not spinning) and the left side of the intercooler were very quiet. Pointing the dB meter as close as I could get to the components and starting from a background of 41 dB in the garage I got the following readings:

Two feet in front, engine running, bonnet up - 78 dB

Right side of intercooler manifold – 87.5 dB

Left side of intercooler - 83 dB

Pivot end of the belt tensioner – 88.5 dB

Tensioner idler pulley – 90.5 dB

Flat idler pulley – 88.5 dB

I removed the belt to check the surfaces of all the pulleys and of the belt itself. I used a brass brush to make sure all the belt grooves were clean. I used a wire brush by hand on the grooves of the alternator pulley and then wrapped about 3 feet of cord around it to spun it, and with a good pull it spun freely and quietly for 4 seconds. The flat idler pulley turned easily with no end play or grit feel as did the new tensioner idler pulley. I Held a wire brush against the AC compressor pulley from the top with long needle nose pliers and rotated it by hand from underneath; when I then spun it, it spun easily, freely, and quietly.

The Alta super charger pulley has resistance to turning but could be turned by hand or with an Allen wrench in one of the three Allen socket head cap screws. I seemed to have some “stiction” and moves in 1 or 2 degree steps as torque is applied to the end of the Allen wrench. It definitely does not spin freely and I assume this is from the vanes in close contact with the inside of the body.

I started the engine without the belt and recorded the sound levels with the dB meter as:

2 feet in front with bonnet open - 70 dB

Right side of intercooler manifold – 74 dB

Pivot end of the belt tensioner – 85 dB

I listened with the stethoscope and there was still noise at the tensioner pivot end without the belt on and it was louder than at the right end of the intercooler manifold but not nearly as loud as with the belt on."


So...That is why I asked about the super charger. The other components seem OK. I was surprised to hear a fair amount of sound at the tensioner pivot apparently coming from inside the block with the belt off, but it is much louder there with the belt on. The dB meter is not as focused as having the stethoscope right on a component so I get a little different distribution from its readings, but the pivot end of the tensioner is definitely the loudest in my stethoscope ears.

 

I would replace the timing chain tensioner it's right under the belt tensioner

 

I had buttoned things up on the Mini and took a short test drive yesterday of about 40 miles and everything seemed normal. Then today I started it to move it to the garage to replace the rear brake pads and there was a loud knock in the engine at idle that I did not hear yesterday. I drove to the garage, pulled it in, and made a video to record the sound which may be coming from the super charger. This is much different than the vibrating sound I heard with the stethoscope and is very sharp and audible. Apparently the German Mini gods are not done messing with me yet. The knock is sort of random, not tied directly to each revolution. Suggestions?

Oops. It won't let me upload the .mov file. It is 19.0 MB Is there a size limit?

 

I uploaded the video of the knock. Perhaps I did not wait long enough in the previous post to click upload because it did not appear to be doing anything.

 

That does not sound like my failing supercharger PTO. My supercharger noise was a consistent, higher frequency rattle than in your sound file.

I would remove the serpentine belt again and run the engine to see if the noise is still present.

I haven't (and pray I never) heard timing chain tensioner noise before but I think MrBlah has good advice above.

 

Thanks for the reply. I had made another video of the seemingly random knock yesterday (7 to 8 knocks in 30 seconds) and was about to remove the belt to video it running without it, but decided to video the AC pulley first, because it appeared at one point to run backwards like the wagon wheel spokes in an old western. While videoing I noticed that the tensioner jumped when it knocked and may itself be the source of the knock sound. (I let it run too long so the file had to be clipped in order to upload it here so ignore the win movie maker overlay). I tried to video it again for a shorter time, but by then it was not making the knock sound, so here is the clipped one that shows the tensioner jumping once or twice at the beginning. I'll try to video it again today starting from cold which is when it seems to knock more. This is driving me crazy trying to determine the increased noise cause and now the knock cause.

 

I suspect the tensioner jump is an effect of (not the cause of) the knock.
When I had my JCW SC out for a PTO rebuild (many years ago) I recall it spinning freely both before and after the rebuild. There was some very slight clogging from the roots vanes but you could grab the pulley and easily spin it with no noticeable binding.

 

Thanks for the reply; not what I hoped to hear, though. I've been trying to think of what the action would be if the SC was making the knock IE hitting internally and being intermittantly hard to turn. Looking at the belt routing, with the tensioner between the crank damper and the SC, it would seem a hitch in the SC would make a bit of momentary "slack" in the belt at the tensioner pulley allowing it to drop a bit and then be pushed back up when the SC broke free? I am trying to get my head around what might actually be hitting what to make the knock sound that seems loud when cold but goes away later.



Maybe I need to pull the wheel and fender liner again to get a better view and/or video of the tensioner

 

Sounds like a PTO to me. I think your PTO bearing is very worn and only engaging the gears in certain areas.

 

Yes, this logic is correct. But it would apply to any of the accessories driven by the belt. Remove the belt and check the other pulleys for smooth rotation by hand. If the SC is the only one that "sticks" then you've found the culprit. If you're really lucky the problem is just the water pump. But if it is the PTO, they can be rebuilt at a reasonable cost.

 

Thanks for the advice. The weather is not good for me right now, but I will again remove the wheel and fender liner to make removal of the belt and hand turning the pulleys easier. I'll try running it again with the belt on first to see if the knock on cold start is still the same.

BTW, my experience with PTOs is with old Ford Tractors, so I had to do a search to find that the term is used here for the gears in both ends of the Super Charger; I hope that is not the problem, but perhaps I can figure some way to spin the SC pulley by itself; maybe remove the tensioner and use a drill motor to drive the belt and SC pulley from above. I assume from the belt routing and arrow that it spins clockwise?