Thread: Supercharger Rotor Pack Noise

2004 GTP with bolt on mods and 3.8 pulley 118000 miles

So I have learned wayyyyy to much about rebuilding an M90 in the last year. Let me try to sum it up for clarity. Last summer I started getting noise from the supercharger area that would go away if i put a wrench on the tensioner pulley. Pulled the belt off and noise goes away completely.

1- Replaced the tensioner and idler pulleys. Noise remained.
2- Pulled snout off M90 and did the coupler. Noise remained.
3- Replaced entire supercharger with one from a yard and installed a new coupler. Noise remained and was worse!
4- Rebuilt the entire snout on original supercharger and reinstalled it. Noise seemed to come and go but was really bad when it was there.
5- Noticed the stock pulley was out of round a bit so I replaced it with the other superchargers pulley. Noise remained.
6- Replaced the second stock pulley with a ZZP modular pulley. Noise remains and the pulley has about couple thousands of an inch wobble still when spun very slowly. Noise remains as soon as the car is warm.
7- Took another supercharger and tore it all the way down and replaced needle bearings (ebay) and I am rebuilding the snout since my out of round pulley may have damaged the last one.
8- Reinstall the nicely coated rotor pack and if I turn the coupler by hand back and forth I hear a bit of slop. Tried a less desirable looking rotor pack and can hear the same slop.

I'm not thrilled about removing the entire supercharger from my car (which now has no belt on it so I can drive the turd) and putting any of the now THREE M90s I own and have to some degree rebuilt because I am beginning to believe that I have three bad rotor packs with pretty good teflon coating/ suet from my egr. Two of them are completely coated black with "something" and one has small chips on the coating near the edge of the rotors.

Help me anyone who has had any experience like this. Ive been creeping on here and ClubGP and MyMonte since and dont ever recall anyone having this kind of luck with 3 superchargers on a low mile car that has had a stock pulley.

Ill try and post some videos of the car running noise and the slop from the bench unit.

thank you!

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Link to noises

First video lost its sound in the upload but it’s the classic marble in a coffee can described by ZZP to be rotor related since it doesn’t go away when you rev or accelerate.

Originally Posted by Scottydoggs

see if you can feel the rotors not moving tight to each other, they should be rather tight with no play inside.

bearings go bad in the back of the case. good news in blowers are cheap. you can get a gen 5 for like 120 shipped from lkq.

Ive done the needle bearings in the back of the case on my latest rebuilt supercharger that was in fact from LKQ out of Idaho. I guess my question for you would be, is it worth putting it back together a third time with what seems to me (though what do I know) like a sloppy rotor pack? The rotors themselves look and seem tight as could be but the gearing on the pack is where all of them seem to have the same little play. Or should I have tried the needle bearings all along and would have fixed it right the first time?

Originally Posted by Scottydoggs

run it then. if you got unexplained kr change it out.

Thanks Scotty. I appreciate what you do for this community. Cheers and I owe you a beer!

I’ve never removed the other belt because it goes away with removing the supercharger belt. The noise is def from the supercharger.

Thanks for the reply bill. The coupler was replaced on all three Superchargers I’ve tried. As were the snout bearings and the needle bearings. The latest installed one as of yesterday and I still have this god forsaken noise once it warms up.

Third supercharger... bad rattle - Album on Imgur

Originally Posted by BillBoost37

That doesn't sound like a supercharger noise to me. Sounds more like lifter or something.

Oh there’s plenty of that too. Right as each rev slows you’ll hear it. Weird how hard it is to isolate even though it’s loud enough to hear with the windows up. I’ll try again from a diff angle.

Try try again...

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So Ive tried another snout because it looked like maybe I had pressed the supercharger pulley on a mite crooked. (I could see how that could happen with even the zzp puller I guess???) went to swap in another rotor pack too but realized the PS pump coolant elbow piece blocks removing the rotors. Didnt have another elbow or coolant on hand and was scared I might make another problem so I put it back together with another snout anyway and def still have the same rattle. I'm debating ordering ANOTHER lkq part because after spending all the time/money/headscratching I've begun losing hope.

Again Ive replaced the needle bearings, snout bearings x2, snout seal x2, coupler x3, pulley x3, Idler x2, tensioner and belt x3. All in a mix and match sort of order and every time the car starts and idles perfectly until I drive it for a few min and the noise persists until it cools completely between driving.

What on earth (besides having three dif rotor packs having gear slop and pretty darn good looking rotors) am I missing or overlooking that only makes the noise with the belt on the supercharger. Also the noise sounds a whole lot like its coming from the coupler and rotor gear area. And its louder than anything I've been able to capture on my iPhone.

another video with the supercharger belt off. maybe I hear the lifters going wild too.
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And the winner is bandook! I wish I had a proper finish to this thread in case anyone ever comes across it in the future. The supercharger seems to be suffering from a general miss diagnosis on my part completely. The harmonic balancer was toast. The outside ring of it literally moved from me pushing on it with my thumb. Got to wobbling and it made the entire belt drive system go wobbling and made noise. Maybe it’s what smoked my water pump last year? Maybe it’s what was causing my supercharger to sound so bad? I’m humbled that I had chased the wrong road as far as I did. But I’ll head back to lurking on this forum and learning from threads far better than this one. Thanks everyone for contributing and keep em on the road! Cheers

Originally Posted by bandook

So the noise goes away when u take the belt off? How does your balancer look? Haven't had one go bad but I hear they get noisy.

PS. It took a 24 mm socket and I used the starter trick referenced on this site and YouTube. It was about the 5th crank of the starter with the plug wires off that broke the crank bolt free. I was getting uneasy about trying that method but the 1/2” impact I had didn’t wanna break it free. Also. There is now a puller kit available from RockAuto, but it’s easy to source the correct bolts to save money. I liked the kit idea since it had a duckfoot puller and the big ass washers included with the proper bolts. Works perfect and included a plug to fill the crank thread hole as to not damage threads. All was easily accessed from the wheel well once I removed the wheel and splash shield. Use a vice grip on the flywheel via the small inspection cover held on by two 10mm bolts near the starter. Clamp your vice grip to the flywheel while minding the teeth of it and it will prevent the engine turning while you turn your puller kit. I against all better judgement blasted the new balancer on with the big half inch impact once the key was aligned to the crankshaft. I reused the bolt to really make sure I was flirting with disaster. Probably should have followed torque specs and replaced the bolt for what it’s worth.