- Joined
- Feb 23, 2023
- Messages
- 285
Eaton M90 Gen III Supercharger Snout Rebuild Guide (1997-2003 L67) This guide focuses on the most common DIY rebuild for the M90 supercharger: the nose drive (snout) assembly, which is responsible for the majority of the rattling and fluid leaks on the L67 supercharged 3800 Series II engine.
The snout contains the pulley, input shaft, bearings, and coupler, and is the primary failure point due to wear.
Required Parts and Typical Part NumbersRebuild kits are the easiest way to source all necessary parts. The numbers below are OEM part numbers for individual components or general descriptions; aftermarket kit part numbers will vary by vendor.
- Snout Rebuild Kit: All-in-one kit including bearings, seal, and coupler. (Varies by vendor)
- Supercharger Oil: Essential lubricant. GM P/N 12345982 (4 oz bottle). You will need approximately 8-9 oz (two bottles).
- Drive Coupler: Connects the snout shaft to the rotors. Dorman P/N 917-009 or upgraded solid unit.
- Front Snout Bearing: Supports the pulley end of the shaft. FAG/SKF/General Bearing: 6206-2RS (or similar C3 clearance).
- Rear Snout Bearing: Supports the rotor end of the shaft. FAG/SKF/General Bearing: 6006-2RS (or similar C3 clearance).
- Shaft Seal: Prevents oil leakage from the snout. (High-temp material recommended).
- Anaerobic Sealer: Used to seal the snout housing to the main case. Permatex 51813 (Anaerobic Gasket Maker). DO NOT USE RTV!
- Supercharger Gaskets: Gasket between the blower and the manifold. GM P/N 24503911 (Plenum Gasket - Sold separately).
Rebuild Steps (Snout Only)This guide assumes the supercharger is already removed from the engine.
1. Removal and Disassembly:
- Drain the Oil: Remove the small drain plug on the snout and drain the old supercharger oil completely.
- Remove the Pulley: Use a specialized supercharger pulley puller to remove the press-fit pulley from the snout shaft.
- Remove the Snout: Remove the typically four bolts securing the snout to the main housing. Gently tap the snout free with a rubber mallet.
- Disassemble the Snout: Remove the snap ring holding the front bearing. Use a hydraulic press or specialized tool to press the shaft and both bearings out of the housing. Do not use a hammer directly on the shaft or bearings.
- Inspection: Clean the housing and shaft. Inspect the shaft for deep grooves where the seal rides. If grooved, the shaft may need replacement.
2. Cleaning and Reassembly:
- Install New Parts: Press in the new rear bearing, then the new front bearing. Install the new shaft seal using a proper seal driver. Install the new snap ring. Tap the new coupler onto the shaft end.
- Seal the Housing: Apply a thin, consistent bead of anaerobic sealer (Permatex 51813) to the snout's mating surface.
- Reattach Snout: Carefully bolt the rebuilt snout back onto the supercharger housing, ensuring the coupler properly engages the rotor shafts.
- Install Pulley: Press the pulley back onto the shaft.
3. Final Step:
- Refill Oil: Refill the snout with the recommended amount of GM Supercharger Oil (approx. 8-9 ounces).
Critical Torque SpecificationsUse these specs for reassembly after the snout rebuild and when reinstalling the supercharger onto the lower intake manifold (LIM). Always tighten fasteners in the specified sequence, if provided in your service manual.
- Supercharger Snout Bolts (Case to Snout): 18 lb-ft (25 N·m)
- Supercharger Housing Bolts (to Lower Intake Manifold): 18 lb-ft (25 N·m)
- Lower Intake Manifold (LIM) Bolts (to Cylinder Head):
* First Pass (Snug): 62 in-lbs (7 N·m) - NOTE: This is INCH-POUNDS.[/color]
* Final Pass: 115 in-lbs (13 N·m) - NOTE: This is INCH-POUNDS.[/color]
[*] Supercharger Bypass Valve Actuator Bolts: 89 in-lbs (10 N·m)
[*] Idler Pulley Bolt (on Snout/Bracket): 37 lb-ft (50 N·m)
Video ResourceFor a visual walkthrough of the M90 snout rebuild process, this video may be helpful:
