I bought this '03 R53 a few weeks ago knowing that it was rattling and had no boost and that the supercharger was the culprit (the mechanics who inspected the car listened to the SC bearings with a stethoscope and told me it was the issue), so I have pulled the SC out of the car and am currently trying to figure out what is wrong with it. I am not overly experienced mechanically, but I would like to attempt to rebuild the SC so long as the rotors and rotor bearings themselves are not the issue, as I have read that it is next to impossible to retime them once you take them out.

To my surprise, the SC seems to be in good condition as far as I can tell.

It had plenty of oil in it (this much):




And all of the bearings looked good (to me at least):





The only signs of wear I see are these small scratches on the rotors:





I have read that scratches such as these are usually indications that the rear needle bearing needs to be replaced on Eaton M-Series SCs, as this bearing controls the radial movement of the rotors, does anyone know if that is accurate?

The other thing I checked for was any looseness of the rotors. I found that one does not move at all while the other moves very slightly:

https://drive.google.com/file/d/1pjw...ew?usp=sharing

I know there is a certain (very small) amount of allowable movement, and I am guessing this may be too much, but I have no way of knowing without prior experience.

I am looking to figure out whether this SC is rebuildable by me (like if it just needed the rear needle bearing replaced, which I'm sure I could do), or if I'll need to send it to Stiegemeier or another rebuild service to do it (and shell out $1100 or more). Any pointers are greatly appreciated!

My R53 has 130k miles.

 

I recently did the supercharger service as well and had similar scratches on the rotors. I only inspected the pulley side, which also looked good.

But this picture is strange...There should be 3 prongs on each side, and they do not protrude through the coupler. Compare your picture below with mine, to understand what I mean.



The pulley side has 3 prongs in the coupler



And the lid has the remaining 3 prongs.



If the lid only has 1 prong left, then you have found the issue

 

Hmm ok, strange that the prongs did not look to be broken off. Do you think that is what happened? I will certainly look more closely, however.

 

Yep, for instance look at the vid around 3:50

 

check your crank damper it will make terrible sounds and your car wont make boost and is far more likely to be the culprit

 

I've never seen rotors that didn't have a little scratching on the rotors - some more than others.

 

This is good to hear, maybe my supercharger is fine after all!

 

I can certainly pull the crank pulley off and check this.

Isn't there supposed to be a smell if the crank damper/harmonic balancer goes out? I haven't noticed any smells.

And for further clarification of what the sound is like, it usually isn't noticeable. It is a rattling noise like metal hitting metal and I believe that it is much more obvious if not only audible at higher RPMs. I babied the car on the drive home (which was a three hour drive) to keep the revs low and I didn't notice the sound at all. I first believed the sound was coming from the back of the car, but the mechanics who inspected it said it was the SC.

What sound would the car make if it were the crank damper? Do you have a video of this so I can compare the sounds?

 

If you've got the SC off, visual/manual inspection of the crank pulley is easy. A friend's '06 went out - it made no noise or smell, but threw CELs and literally fell apart when I pulled the belt. The pre-facelift crank pulley is a different design but should be easy enough to check. Look for cracks in the rubber.
All that said, how about a pic of the SC nose - as nd-photo pointed out, that coupler just doesn't look right.

 

Here you go - is this what you were looking for?