Write-Up: 95sc Changing the coupler in an Eaton m62

Ok hi all. From what I understand the 1995 series 1 s/c coupler repair is done differently than the 1996 and up series 2. I have a 1995 that is rattling badly and I cant seem to find to much info on how to do it. Has anyone on the board done this on a 95 series 1 and if so How do you check the oil? Where do you refill it? And a little advice on the general procedure on changing the coupler. And how difficult is it? I'm somewhat mech inclined and have the tools Im shure so thats not an issue. Any help at all would be appreciated. Thanks Ray

http://www.cardomain.com/id/kennlee

Write up: 95sc Changing the coupler in an Eaton m62

There are two methods that the coupler can be changed on the Eaton M90 supercharger. It can be changed with the SC both on or off the car. This is not true for the Eaton m62. The M62 has a bolt that goes through the alternator and tensioner pulley bracket which makes removing the snout with the body still attached to the LIM very difficult. I suppose you could try and remove the bracket, however it is attached in a large number of places and even when swapping my LIM, I left it in place. This write-up is going to assume that the supercharger is off the car. If you need to find out how to remove your supercharger, have a look at the write up for swapping the LIM in the write-ups section. Follow the directions in that writeup in the removing of the vacuum lines, electrical connectors, and throttle body bracket. Once the supercharger is free of the LIM, it can be gently lifted up off its alignment pegs, slid away from the alternator bracket, and then can be lifted straight up. With the supercharger off, this might also be a good time to do a good throttle body scrubbing too.

The first thing to do is have a look at all the nice bolts holding the snout onto the supercharger. Go ahead and find a 10mm deep socket.



Before removing the bolts, open the oil drain plug and pour out all that foul smelling stuff.



Now remove all the bolts noting where each came from. The first picture in this writeup can be used to get the bolts with special heads back where they belong. Once all the bolts are out, gently pull straight out on the nose section. If it won't move, carefully pry using a small block of wood and a large slot screwdriver at the rectangular recessed part that is in the upper middle of the above picture near the tip two bolts. Once you have carefully broken the seal you should be able to pull the rest of the nose off by hand. Enjoy the smell and try and clean up all the oil with a clean rag from both sections.

Below is the old coupler, there was about an 1/8” of play in it. By just holding the pulley and rocking it back and forth on the car, it did not feel like so much.



Here we see both halves after a quick clean down.



Remove the old coupler and give it another quick oil cleaning.



Press the new coupler down by hand and prep the surface for re-sealing. I don't recommend using a gasket scraper as the mating surface is VERY well machined and any scratch would wreak that surface. I used acetone to further clean both mating surfaces.



Now add the smallest bead of Red Gasket maker that you can along the lower mating surface. Try and keep near the outside edge. Note that the SC is up on end so that leftover oil will not run down onto the clean and prepped surface.



Ensure that the pins are lined up for the nose drive to slide into the coupler correctly and gently lower the nose drive down onto the bottom section. Do not wait for the gasket maker to set, but torque all bolts in order( I used clockwise) to around 11 ft/lbs( I went with “tight”).



Rag off the gasket maker that squeezed out. You should have a little less than is in the above picture. Let the SC sit for 24 hours in the below position before installing.



Don't forget to put in new GM SC oil and use a new SC gasket before re-installing the SC. Felpro gasket # is FEL MS9574.1Also the SC might enjoy a bath before putting it back onto the car.

Alright, well, when I had the camshaft position sensor replaced, the mechanics noted that they heard some noise from the S/C like a bearing problem. I was in doubt first, but as I hear it I realize that this sound has always been there while I had the car. The S/C feels fine but there's definitely the sound of a loud bearing. I'm wondering what I should do, should I change the oil? Buy a durable ZZP or something replacement? What's everyone's best advice, and what's the worst that could happen if I leave it as it is and continue driving?

It's probably the coupler, not the bearing. An $11 part. It sounds like a bad bearing, but it isn't.

Ahh right, that's the real name, the coupler, haha I forgot that! To swap it you need to take the S/C off and apart right? Not something I could do.

Since your nose of your SC has a post that sticks into the alternator/tensioner bracket, it means you would have to pull the SC off the engine to change the coupler. Its really not too hard actually, you could do it with a few hand tools and a SC gasket. As long as you take your time, take pics of where the vaccum connections are, its pretty straight forward. Once the SC is off, you will need a coupler and some SC fluid.

https://rivperformance.editboard.com/series-i-engine-transmission-f13/write-up-95sc-changing-the-coupler-in-an-eaton-m62-t4421.htm

If you break that gasket on the mating surface make sure you use anaerboic gasket maker since the s.c is aluminum.

Well there's no way I'm doing it myself. Anyone know what kind of damage this could cause in the long term? I'm gonna save up for now until I have some money in my pocket to get it done.

Likely no damage will result. I ran mine noisily for over a year before fixing. If the coupler were to fail, it would frag inside the snout, and the blower stops working. It's a sort of a mechanical "fuse".

yeah, it just makes a knocking for the most part. To see how far out it is, you can take the belt off and just turn the SC pulley back and forth to see the play. Mine had maybe less than 1/16 of play and that was enough to make it audible. I've heard them being out as far as 1/4" with no I'll effects, although at that point it would sound like raining cannon balls and I woulden't let it go much further.

I'm used to that rattling sound actually, it only comes up when I let off the gas so it sounds kinda neat! Gives away the secret to anyone riding in the car who doesn't know but that's not a big problem anyway.

Am i correct to assign this as the cause of a very loud idle? It's not "marbley" really, just very industrial and noisey.

Yes, that's likely the cause, in combination with an opened intake (esp FWI). When you fix the coupler, the rattle noise will go away, but there will still be the breathing sound from the intake.

AA wrote:

Yes, that's likely the cause, in combination with an opened intake (esp FWI). When you fix the coupler, the rattle noise will go away, but there will still be the breathing sound from the intake.

Yea with a FWI, that noise is not pleasant!

In the winter, it was so loud with the bad coupler + FWI, I could hear the car inside the house with door closed, almost 100 feet away!

Now, I can't hear it 20 ft away.

I don't mind it so much on the road, it sounds pretty cool while driving, but I suppose I could do without the extra volume/noise. I can hear it through my house too. I'll get around to doing it eventually.

Is the coupler job as labor intensive on the Series II as the SeriesI?

Series II is e-a-s-y. Remove the snout, replace the coupler, put it back together, new SC oil, done in 1-2 hours.

I don't have a belt-putter-oner, or a garage, I might have the right socket wrench somewhere, and I'd really rather not expose my intake manifold to outside air and bugs, or try to remove and refit my alternator.

I'll save up pocket money and have the dealer do it for an hour's worth of labor.

AA wrote:

Series II is e-a-s-y. Remove the snout, replace the coupler, put it back together, new SC oil, done in 1-2 hours.

Is a puller needed to remove the snout?

Nope, just a socket wrench and extension.

FWIW most dealerships I've dealt with consider the supercharger R&R only - they will replace the whole supercharger with a rebuilt for big $, as the coupler is not available separately from GM. I don't think you can buy it from Eaton either, or at least that's the way it used to be.

You can certainly try the dealership, but you might have better luck with a good local mechanic. I suspect you'll meet with some blank stares at the service desk while they try to figure out which part you want installed...

Actually, the guys at the service department here might do the coupler for me without telling me I need to do the whole S/C. They know they can't bullshit me because they know that I know that superchargers won't 'fail' until at least 150,000 miles, if ever. Otherwise, they'll probably let me buy a coupler from ZZP or something and they'll install it, just without their warranty on the parts or labor.

Maybe so, but even mechanics I've been doing business with for 15 years don't appreciate it when asked to install parts provided from outside. This is because they make most of their profit from margins of parts sales (mark-ups). If they just collect for labor, they're only breaking even at best. They play the warranty card to try and dissuade customers from doing this.

If they seem hesitant, they aren't trying to bullshit you, they're just trying to make a living. If they seem willing, they're being really nice, doing you a favor. My rule is, if I want to install an aftermarket part, I put it on myself, or I pay a performance shop who can acquire the parts for even less.