How to replace an M90 snout coupler
Writeup by Will "Overkill" Rishworth of OQCGP

The day was April 19 2002, a Friday, the day after my college semester had end and I was free for 3 weeks. I was happy to have time off so I decided to relax and enjoy by working on my car, the plugs and wires had to be changed. Half way into the procedure of changing the back plugs, I realized that the blower snout may be able to be taken off quick easily. My blower had 229,000kms on it, while in good shape it rattled at idle and I had a new coupler in my basement which was supposed to fix the problem. With a call to crazy Alex to bring some oil for the supercharger, I decided to attempt the snout removal. Here's what happened:


Here is the work in progress when I decided to take the snout off. As you can see the rear plug wires are removed as is one of the dog bones to provide better access to the rear plugs. All that's necessary to remove the snout are the 10 bolts holding it onto the housing. To start the work I figured space on the passengers side would be essential so I removed the fuse box by taking the cover off, then the 13mm nut attaching the power lug atop of the box, popping the lower box apart and taking it out. I also removed the belts by letting loose the tensioners with a 15mm ring wrench.


First thing needed was to get as much supercharger oil out of the snout as possible. To do this I found my syringe from my tooth surgery last christmas in my bathroom, it was all I could think of for a quick solution and it worked very well!

Once the oil is extracted from the snout I dumped it into an empty supercharger oil bottle in my trunk. I managed to salvage half the oil which was going to be needed since only one fresh bottle of oil could be found on such short notice.


Troubles already, some of these bolts are going to be difficult to get to. Two are impossible without removing the alternator soooooo.....

Off it must come! Remove the nut for this brace and there's another one easily accessed at the other end. They'll take a 13mm socket. Then use a deep socket or wrench 13mm to remove the bolt that was behind the brace.

There are three more to come out. The first one is hidden to the left of the tensioner beneath where the alternator is sitting, it takes a 13mm again with a small extension on a socket. The remaining two are at the back of the alternator and are moved with 13mm yet again, might be able to get a socket on them but I used a ring wrench.


With the alternator removed you can see how easily you can get at these bolts. They are all 13mm in size so grab for the sockets you just used for the alternator.

This bolt is the most difficult one, a rachet won't fit so I used a standard socket bar which is less bulky at the end and it managed to fit just fine.

There's one more bolt down here, just use a long extension to give yourself space to get a rachet on and it comes right off. Now remove the rest of the bolts and set them aside. Notice the bolt that goes up and down behind the snout, its longer than the others so remember which one it is, this secures the snout to the intake manifold.
*Note*: The gasket for the supercharger extends out to cover this bolt hole, by removing the snout you will end up ripping this gasket however it stayed stuck to the bottom and was reuseable, since it is not covering any air passage ways I don't forsee any leaks, I will know for sure in a few weeks time when the entire blower comes off to grease the bearings at the other end of the impellers.



Success! Using a rubber mallet I was able to shock and wiggle loose the snout. Prepare for the oil spillage out of the snout, nothing much you can do about it, you'll clean it off later. Notice the assembly is coming off with the impellers stuck to the snout, whack it gently with a rubber mallet and try to get a flat blade screwdriver in there to separate the two.


You can now see how the blower is in 3 pieces: The snout, the section with the impeller blades, and the housing.

Notice the coupler attached to the snout, it couples onto the right hand side gear which turns the other side as well, pretty basic stuff and its that coupler that's rattling. Note that the impeller unit will not come off with the alternator bracket in the way. Now take some paper towel and whipe up as much oil as you can, I also sprayed down the engine with degreaser at the end of this installation

Holding the blower in my left hand, I could rattle the coupler on its pegs. According to Mike Wood this is what happens, sure enough he had his old coupler with him which we slapped on and rattled on the pegs.

Update April 1, 2003
I'm finally finishing the installation instructions and updating pics on a new coupler which I'm now using

Here's the new coupler I'm using, its a ZZP unit. I've gone through 2 stock couplers now, even my new coupler last year started rattling on the pegs after only a few months. This time, ZZP had a new coupler to use this time around. I was fairly impressed with it, it seems more bulky, a harder compound and will hopefully withstand oil a lot better than the black composite material of the factory unit.

This time the supercharger came off for a cleaning so I'll show some pictures from this but its the same instructions for if its on the car :) First step of putting everything back together was to take some brake cleaner and spray down the rotors and behind to get rid of all the black guck, afterwards it was all nice and clean. Now lets put that coupler on the gear pegs!

The new coupler was purchased from Zooomer for $40US with shipping. I lubed the pegs with some simple s/c oil to help slide her home. The holes with the lip on the outside go towards the pegs that're about to slide through the holes, notice the holes left for the snout pegs for the correct alignment. Once pressed on it was a nice tight fit, no looseness at all. I then took the brake cleaner and cleaned out the inside of the s/c snout, get rid of the nastiness! Once clean, it was ready for some sealer. For this I used a normal gasket maker or RTV silicone, something to create a seal between the metal surfaces since after all there's oil being held in here! Be nice and thin with the sealer, no need for a big bead that's gonna go splat, just a nice thin line all around. Also put some oil on the pegs on the snout. Now to reattach the snout to the rest of the s/c.

Peering between the snout and the rotor housing, I lined up the pegs to the holes on the coupler. Once I got the pegs started, I gentley push on the snout housing and it starts to slide on. To line up the snout with its mounting tabs, on two of the bolt holes there are protrusion. Once lined up the snout will push right into place. Now time for the bolts and to start tightening them snug, for the final tightening use about 15ftlbs on your torque wrench. If you're not sure what this is, give it your best guess. Remember that you're screwing into an aluminum housing so don't reaf on the bolts! Just a nice snug bolt is all that's needed. I wiped off sealer that came out the sides with a rag, I'm a maid I know. You may now fill the snout with your favorite s/c oil, which in most cases should be genuine GM oil :) you'll need 3 bottles of that stuff, fill it right up to the bottom of the threads on the filler plug! 2 bottles will come close enough but I suggest 3 to go all the way and keep the rest for whenever you need it next.

From there installation is the reverse of removal. Pop the alternator back on, put the belts back on, reconnect the fuse box, and I was back to where I started from. I finished my plug and wires change plus a thermostat and started the car up to reveal no leaks, misfires or other abnormalities. Sometimes I even think I know what I'm doing!