FAQ: Supercharger Noise (Bad Coupler)

can you feel this or just hear it. Do you have an open cone on the intake or a gutted or stock airbox?

I would describe the supercharger noise at cold idle like marbles in a blender. It tends to quiet down once the car warms up. That's what the OEM muffler and baffling in the airbox is for.

Could this also be a worn out coupler?

manofmany wrote:

That can only been heard with everything off, at idle, while in drive? It's almost non-existent in N. It's been around for a good 20k miles but seems to be getting progressively louder. Can't seem to isolate the noise but the car runs great.

Almost sounds like the engine is shaking. Anyone else experience something like this with a bad motor mount?

I would check the motor and transmission mounts, all four of them; I would take a look at the harmonic balancer; I would slip off the belts and turn pullies (is it the water pump) and I would look for a loose heat shield above the cat.

to start.

Albertj

RidzRiv wrote:

Could this also be a worn out coupler?

good call. a high mile coupler will make some marbl-ey sounds.

OK let's "take this from the top"

bad coupler - at idle the engine will not look like it is shaking, and you will be able to put your hand on the supercharger snout (STAY AWAY FROM THE ROTATING PARTS) and feel the "marbles."

bad mounts - if the mounts are good the engine idling looks the same as the engine off, except for the rotating parts moving. Really. If the mounts are not good, the engine may or may not vibrate; it will move a lot in the cradle when you blip the throttle, though. Matter of fact if the mounts are bad you can make the engine slam around by blipping the throttle at idle, and what's more if you "stand" on the brake with the hood open and put the car in gear you will see (and feel) the engine slam into the mounts.

My guess is that at your car's age and mileage you have both issues.

Albertj

If it were the coupler, perhaps the reason the sound goes away in neutral is because the boost bypass valve is open. Does the sound go away in reverse too? I confirmed that my coupler needed to be replaced by removing the supercharger belt and turning the supercharger pulley back and forth. Any play you can feel is an indicator that you need a new coupler. After I replaced my coupler there was no play in the pulley. The sound was the loudest on mine after turning the engine off.

Also consider taking a long flathead and pressing it against different parts of the motor then puting your ear to the end of the screwdriver. Try to locate exactly where the sound is coming from.

"I would describe the supercharger noise at cold idle like marbles in a blender. It tends to quiet down once the car warms up. That's what the OEM muffler and baffling in the airbox is for."

How do the baffling in the airbox and the oem muffler prevent this during warmup? is it specifically sound that they hinder or do they also lessen engine wear during startup?

my dad randomly told me last night that were takin car to a freinds to let them do it because our garage will not be ready soon. just got back from dropping her off. hope shes in good hands

just found out my supercharger is no good i need to know if there is a kit for rebuilding it or if someone knows were i could get a reliable used one for sale. or wats prices for a new one????????

crstump wrote:

just found out my supercharger is no good i need to know if there is a kit for rebuilding it or if someone knows were i could get a reliable used one for sale. or wats prices for a new one????????

What makes you believe it is no good? The Eaton supercharger is very durable. When they rattle, it's usually just a worn coupler. The coupler is easily replaced, especially on the the M90.

my dads friend is one that looked at it. the pully has play in it. like the shaft and all is moving. im not sure if its not good at all or not thats why i come here for advice.

crstump wrote:

my dads friend is one that looked at it. the pully has play in it. like the shaft and all is moving. im not sure if its not good at all or not thats why i come here for advice.

Yes, that could be a bad coupler. The coupler is a small plastic disc with 6 holes in it. It couples the pulley shaft to the rotors. The holes become oblong and that causes play. That play causes a rattling noise at idle. Have a look at this video.

https://www.youtube.com/watch?v=pSsSctYvOoI

What year is your car? The 95's use the M62 supercharger. The 96-99 use the M90. Replacing the coupler on the M90 is easier than the M62.

96, 121000 miles. i now believe it is a coupler after watching video, i will have dad give his friend a call and we will see what he says

crstump wrote:

96, 121000 miles. i now believe it is a coupler after watching video, i will have dad give his friend a call and we will see what he says

Coupler is cheap and easy to do.

http://shop.zzperformance.com/store/p/63-Supercharger-Coupler.aspx

im going to ask if we can ride out there today to take a look at it. thanks for the advise.

Good Ol' Larry, Johnny on the spot with good advice or a fix.

Thanks guys! I changed out the coupler and threw in some new oil and everything is silent again!

The old one FELT like it fit good on the pegs but after I put the new one on, I realized it wasn't tight at all!

So im reading all these posts about the rocks in the supercharger sound, my car sounds like that now, i use a stethescope to try and pinpoint the noise. The noise is more pronounced when i place the scope behind the snout where the gear is for one of the rotors.im.going.to perform the test that ibsaw in here snd see if theres play, hopefully its just the coupler::crosses fingers::

It's certainly the most common problem...these superchargers never really break in any form unless something stupid was done to it.

Yeah just order the whole kit with the green coupler from zzp today. I shoud've done it when i had the snout off the first three times. Lol when i hear the rattle everytime i shut the car off i cringe. Didnt understand what the function of the coupler until i really thought about it. Had a dee duhdee moment.

Yeah at shut down it's pretty bad sometimes lol. You'll love your car in a whole new way when it's done.

My 95 Riv (series 1 SC 3800) started making a horrific noise that I thought was the failure of the coupling in the supercharger based on all the information I gathered here. This went on for a couple weeks and then one morning I started the car and no noises. The car drove great and I can hear the normal "whistle" of the supercharger when I punch it.

I took the car to the garage and they tell me I need to replace all three tensioners. That was based on them using their "stethescope" to listen to them and that was the cause of the noise I heard rather than the failure of the coupling. I am highly doubtful that they know what they are talking about.

Anyone ever heard of this before? Secondly has anyone ever had that wonderful "supercharger full of rocks" noise just go away by itself?

Again, thanks for any input you wish to offer.

The rocks noise is your coupler. It really won't hurt much if you leave it but it's such an easy and cheap job to do yourself that it doesn't even matter. That being said if you haven't replaced any of the idler/tensioner pulleys you should do them ASAP with some nice ones such as Gates or Delco. I personally prefer metal ones (which the Gates ones are, can't speak on the Delco ones) but it doesn't seem to matter too much performance or durability wise. I'm sure I'm not alone in saying that I've been stranded from a fragged pulley, specifically the bearings seized up causing the pulley to come apart and throw the belt into everything. Not fun.

Please see the appropriate threads.

Pulleys:

https://rivperformance.editboard.com/t4451-faq-fragged-tensioner-idler-pulley-reports-questions?highlight=pulley

https://rivperformance.editboard.com/t725-write-up-replacing-belts-and-pulleys?highlight=pulley

https://rivperformance.editboard.com/t5963-write-up-replacing-belt-tensioner-pulley-series-i?highlight=pulley

Coupler:

https://rivperformance.editboard.com/t3009-faq-supercharger-noise-bad-coupler?highlight=coupler

https://rivperformance.editboard.com/t6718-write-up-supercharger-coupler-replacement-series-ii?highlight=coupler

designer1962 wrote:

My 95 Riv (series 1 SC 3800) started making a horrific noise that I thought was the failure of the coupling in the supercharger based on all the information I gathered here. This went on for a couple weeks and then one morning I started the car and no noises. The car drove great and I can hear the normal "whistle" of the supercharger when I punch it.

I took the car to the garage and they tell me I need to replace all three tensioners. That was based on them using their "stethescope" to listen to them and that was the cause of the noise I heard rather than the failure of the coupling. I am highly doubtful that they know what they are talking about.

Anyone ever heard of this before? Secondly has anyone ever had that wonderful "supercharger full of rocks" noise just go away by itself?

Again, thanks for any input you wish to offer.

They are probably correct.

An easier way to test instead of "stethoscope" is to slip the belt off the pullies then turn pullies by hand. The bad ones will grind and/or scrape. You need to replace them SAP because they will run for a while all buggered up then they will suddenly seize, wehich makes a big mess.

Harvey, I think your gut is correct here. The noise description seems like the SC coupler is failing. This is totally unrelated to the tensioner/idler pulleys, which may or may not be at fault. We really don't know for sure, and for what it's worth, I've had my car misdiagnosed for bad pulleys on more than one occasion by professionals who didn't get it right.

One clue is the fact the noise comes and goes - a coupler can do that depending on applied torque, ambient temperature, and severity of the damage. For example, coupler noise always seemed worse for me when cold, then got softer once warmed up.

Bad pulleys in my experience make a sound that gets louder and louder until they fail. It's a grinding sound that coincides with engine RPM. Pulley's don't sound like a bad coupler, but you need to know what to listen for.

I would have the coupler replaced, and with the belts off inspect the pulleys. If they seem all right, run the car and listen for sounds. Tensioner/idler pulleys can be easily swapped at any time, except for the steel one located inside the engine mount - that one requires a couple hours labor.

Best of luck!