This procedure covers the removal and replacement of the engine cooling fan assembly on a 1966 Chevrolet Corvette with 327ci V8, including the fan blade, fan clutch (if equipped), and pulley components.

Warnings

Tools required

Parts

• Cooling fan blade × 1 — Use OEM specification
• Fan clutch (if equipped) × 1 — Use OEM specification
• Fan shroud mounting hardware × 1 — Use OEM specification
• Upper radiator hose clamps (if damaged) × 2 — Use OEM specification

Fluids

• DEX-COOL Extended Life (Orange) — 10 qt

Preparation

1. Ensure engine is completely cold to the touch
2. Park vehicle on level surface and engage parking brake
3. Disconnect negative battery cable to prevent accidental fan engagement if testing electrical components
4. Place drain pan under radiator drain petcock
5. Remove radiator cap slowly to release any residual pressure

Procedure

1. 1

   Drain coolant from radiator
   Open the radiator drain petcock located at the bottom of the radiator on the driver side. Drain coolant into a suitable container. You do not need to drain the entire system, but lowering the level below the upper radiator hose connection will prevent spillage during fan removal.
2. 2

   Remove upper fan shroud (if equipped)
   The 1966 Corvette may have a two-piece fan shroud. Remove the 4 bolts securing the upper fan shroud to the radiator support. Carefully lift the upper shroud section up and away from the engine bay. If the shroud is a one-piece design, it may need to remain in place or be partially loosened for clearance.
3. 3

   Disconnect upper radiator hose (if needed for clearance)
   If clearance is insufficient to remove the fan assembly, loosen the hose clamp at the radiator connection using a screwdriver or pliers. Gently twist and pull the upper radiator hose from the radiator neck. Be prepared for residual coolant drainage. Set hose aside away from work area.
4. 4

   Access fan mounting bolts
   The fan assembly mounts to the water pump pulley. Identify the fan mounting configuration: either the fan mounts directly to the water pump hub with 4 bolts, or it mounts to a fan clutch which then bolts to the water pump. Inspect to determine which configuration your vehicle has.
5. 5

   Remove fan blade assembly
   For fixed fan: Remove the 4 bolts securing the fan blade to the water pump pulley hub using a socket and wrench. You may need to hold the pulley steady while loosening bolts. For fan clutch equipped: Hold the water pump pulley steady (a belt or pulley holding tool helps) while loosening the 4 fan clutch mounting bolts using a socket and wrench. Thread direction is standard right-hand thread (counterclockwise to loosen) for these fan and fan clutch mounting bolts. Carefully lift the fan assembly straight up and out of the engine bay, minding the radiator clearance.
6. 6

   Inspect fan blade and clutch
   Examine the fan blade for cracks, chips, or damage, especially near the mounting holes and blade tips. Check for proper balance by spinning the blade freely. If equipped with a fan clutch, test clutch operation by spinning the fan blade: it should spin freely when cold and offer moderate resistance. Excessive free-play or binding indicates clutch failure.
7. 7

   Separate fan blade from clutch (if applicable)
   If replacing only the fan blade or only the clutch, remove the 4 bolts securing the fan blade to the fan clutch assembly. Keep hardware organized for reinstallation.
8. 8

   Clean mounting surfaces
   Clean the water pump pulley hub mounting surface using a clean rag. Remove any old gasket material, corrosion, or debris. Inspect the water pump pulley for cracks or wobble that might indicate water pump bearing failure.
9. 9

   Install fan clutch or prepare direct-mount fan
   If using a fan clutch: Attach the fan blade to the fan clutch using the 4 mounting bolts, ensuring proper orientation (curved blade tips should face the radiator). If direct mounting: Proceed to next step with the fan blade ready for installation.
10. 10

    Install fan assembly to water pump
    Carefully lower the fan assembly into position, aligning mounting holes with the water pump pulley hub. Install the 4 mounting bolts finger-tight first to ensure proper alignment. Tighten bolts in a cross pattern to ensure even seating. Since no torque specification is provided, tighten bolts firmly using hand tools, approximately 30 ft-lbs for this application (verify against factory specification). Do not over-tighten as this can damage the fan or water pump.
11. 11

    Verify fan clearance and operation
    Before reinstalling shroud or hoses, manually rotate the fan blade assembly through a complete revolution. Verify at least 1 inch of clearance between fan blade tips and radiator core at all positions. Check that fan does not contact any hoses, shroud components, or radiator. Listen and feel for any binding or unusual resistance.
12. 12

    Reconnect upper radiator hose
    If the upper radiator hose was removed, slide it back onto the radiator neck and position the hose clamp 1/2 inch from the end of the hose. Tighten the clamp securely but do not over-tighten to avoid damaging the hose.
13. 13

    Reinstall fan shroud
    Position the upper fan shroud (or complete shroud assembly) back into place, ensuring the fan blade sits centered within the shroud opening. Install the 4 shroud mounting bolts and tighten securely. Verify the shroud does not contact the fan blade at any point during rotation.
14. 14

    Refill cooling system
    Close the radiator drain petcock. Refill the radiator with conventional ethylene glycol (green) coolant mixed 50/50 with distilled water through the radiator filler neck. Fill until coolant reaches the bottom of the filler neck. Allow coolant to settle for several minutes and top off as needed.

Reassembly

1. Reconnect negative battery cable
2. Double-check all fasteners are tight and all tools have been removed from engine bay
3. Verify fan blade has proper clearance from radiator and shroud by manually rotating the assembly

Verification

• Start engine and allow to idle. Observe fan operation for smooth rotation without vibration or noise
• Check for coolant leaks around the radiator hose connections and drain petcock
• Allow engine to reach normal operating temperature and verify fan clutch engages (increased fan speed and noise) or that fixed fan provides adequate airflow
• Check coolant level after engine cools and top off if necessary
• Verify no contact between fan blade and radiator or shroud during operation

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