How-To Eaton M90 Gen V Supercharger Snout Rebuild Guide (2004-2007 L32)

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Eaton M90 Gen V Supercharger Snout Rebuild Guide (2004-2007 L32) ​

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This guide is tailored for the Gen V M90 found on the L32 3800 Series III engine. While the process is similar to the Gen III, the internal parts and oil volume are different. This addresses the common issue of a noisy or leaking nose drive (snout) assembly.

The snout contains the pulley, input shaft, bearings, and coupler, and is the primary failure point due to wear.​

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Required Parts and Typical Part Numbers

Rebuild kits are the easiest way to source all necessary parts. NOTE: You MUST use a kit/parts specifically designated for the M90 Gen V or L32 supercharger.

• Snout Rebuild Kit (Gen V): All-in-one kit including Gen V specific bearings, seal, and coupler. (Varies by vendor - e.g., aftermarket L32 kits).
• Supercharger Oil: Essential lubricant. GM P/N 12345982 (4 oz bottle).
• Supercharger Oil Volume: The Gen V M90 generally requires around 6.9 to 7.5 ounces of oil. This is typically less than two 4 oz bottles. Always refill to the plug hole level.
• Drive Coupler: Connects the snout shaft to the rotors. Must be compatible with the Gen V shaft.
• Front/Rear Snout Bearings: Must be Gen V specific sizes/specifications.
• Shaft Seal: Prevents oil leakage from the snout. Must be Gen V specific size.
• 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. Use L32 specific gaskets.

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Rebuild Steps (Snout Only)

This guide assumes the supercharger is already removed from the engine.

1. Removal and Disassembly:

• Drain the Oil: Remove the drain plug on the snout and drain all old supercharger oil.
• Remove the Pulley: Use a specialized supercharger pulley puller to remove the press-fit pulley from the snout shaft.
• Remove the Snout: Remove the 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. 6.9 - 7.5 ounces). The correct level is flush with the bottom of the fill plug hole.

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Critical Torque Specifications

These specs are generally consistent between the Gen III and Gen V blowers, but always verify with a reliable L32 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)

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Video Resource

For a visual walkthrough of the M90 snout rebuild process (which is largely the same for the Gen V), this video may be helpful:

 

How-To  Eaton M90 Gen III Supercharger Snout Rebuild Guide (1997-2003 L67)