Where to find a service manual for a eaton m-90 supercharger.

USA car? country matters for sure buying parts.
WRECKER, OR OEM
car is old parts are hard to find on most old cars that old.
best is retire that supercharger. and be happy.
google for parts
or here
wreckers network, us it? they too ask country and VIN is best.
https://www.car-part.com/

This is very smelly oil so make sure to be prepared with some latex gloves.... You should change this oil ever 50 to 75 thousand miles. To do this you need to turn out the hex plug on the snout of the M90 eaton charger. Take a pump from a lotion bottle that is clean and dip the tube allll the way into the hole(reservoir). Now pump the fluid out into a plastic jar of some sort. There will be aprox. 6 ounces of fluid in the snout housing. Refill with GM supercharger oil only!!

This is simple!!! I had the same problem in my GS. The part is called the supercharger coupling. It is made of nylon and can't be bought from the dealer BUT can be found in Ebay for about $30. This is a NEW part for the Eaton M90 supercharger. That is all it is!! The holes in the coupling wear slightly oblong creating a little bit of slop and it sounds TERRIBLE.

Be careful with the sealing surfaces behind the supercharger snout, reseal with a gasket maker (Loctite makes some) and refill with the correct fluid.

That my friend is something that is hard to do at home,unless you have a Full Fledged Machine Shop!
Some things best to be left to the pro's!

The L67 motor in the park ave ultras use a Eaton m90 supercharger. The coupler in the noise cone will go bad. Try replacing the coupler. Can usually purchase one for 40.00 from a shop that rebuilds them. Hope this helps.

Remanufactured nose drive kits consisting of nose cone, drive pulley, lubricant,
sealant and coupler are available. The nose kits are an excellent alternative to replacing an
entire supercharger when dealing with low mileage bearing noise or leaky seal concerns.

This was from a service bulletin in June 2003.

There is seal kits.available for the.m 90 supercharger on the 3800 go to zzperformance.com youl find an eye.full off aftermarket and hard to find parts for the gtp.

No leak, it may be time for a service to your supercharger. There is maintance that most people don't know about and the bearing to the supercharger's wear out and then has play. The bad things is with the play the lobes in the supercharger starts to rub against the housing and then the tolerace clearance is larger then when the car was new. Long story short, time to have your supercharger rebuilt before it fails and kills the engine too. There is an other way you can look in too, here is there web page http://cartuning.ca. Good luck

It is the boost bypass valve. The plunger will move with only enough throttle as it is connected to the throttle body.
The bypass solenoid you need is for the Eaton M90, the supercharger on your car. You can very likely get this part from zzperformance.

On the supercharger snout, located immediately to the right of the coil pack mounted closest to the supercharger, is the supercharger oil plug. It is a hex nut that uses a 3/8" allen wrench.

When the engine is cold, remove the plug. You can use any item of your choice that will create vacuum such as a siphon, a turkey baster or my favorite is a squirt bottle nozzle with about a 12" line on it.
Insert your hose into the reservoir hole and remove as much of the oil as you can. If you use the squirt bottle nozzle then if the hose is long enough then you should be able to "snake" the hose down into the reservoir almost the entire length of it by pushing the end of it toward a "1 o'clock" position if you are standing directly in front of the car.
Squirt the oil into another container. If your oil is the GM supercharger oil, it is animal fat based and biodegradable and can go in your regular trash.
Refill with GM supercharger oil or any other appropriate lightweight oil specified to meet requirement for the Eaton M90 supercharger. An equivalent oil can be purchased from www.zzperformance.com.
Fill the reservoir until the fluid reaches the bottom of the fill hole threads.

As an added note, if you lose the hex nut cap for the reservoir it isn't necessary to order a new one. A 7/8" fine thread bolt will fit perfectly but be careful not to torque more than 8ft/lbs with either the nut or bolt.