Eaton M90 Superchargers are air pumps that allow the engine to produce more power at lower RPMs. The Model 90 series is designed for cars and light trucks with 3.0 to 5.0 L engines. Eaton M90 Superchargers are well known for durability, but a few specific problems often occur over time.
The owner of a vehicle with an M90 supercharger might notice consistently low oil levels. The seal on the snout often leaks oil as the supercharger ages. Examine the snout and look for oil to determine if this is the problem. A build-up of dirt and grime surrounding the snout seal is also indicative of a leak.
Bad bearings in the supercharger might cause a sound similar to marbles rolling back and forth. Remove the belt to the supercharger and start the car. The supercharger's bearings must be replaced or rebuilt if this test stops the sound. The vehicle will run without the supercharger; a bypass valve allows air to flow through the cylinders.
Scuffing on the rotors and the end plate indicate the bearings are experiencing wear. The bearings in the front-bearing plate are the only ones that control back and forth movement. The rotors move as these bearings wear, scuffing the rotors and end plate. Replace the unit with a re-manufactured rotor assembly.
A common noise associated with the supercharger is a rattle. Remove the supercharger belt and move the pulleys back and forth by hand. If the pulleys show a backlash, then the coupler must be replaced.
