How to Remove and Install the Gearcase on 75 and 90 HP Evinrude E-TEC Outboards

If you own a 75 or 90 horsepower Evinrude E-TEC outboard motor and need to perform maintenance on the gearcase, this guide will walk you through the process. It's essential to follow the correct steps to ensure safe and proper removal and installation of the gearcase. We will provide you with clear instructions, important specifications, and precautions to make the process easier for you.

Understanding the Gearcase

The gearcase, also known as the lower unit or lower gear housing, is a crucial component of an outboard motor, including the 75 and 90 horsepower Evinrude E-TEC models. It houses important gears, bearings, and seals that transfer power from the engine to the propeller, allowing the boat to move forward or backward. The gearcase also contains the water pump, which circulates water to cool the engine. Proper maintenance of the gearcase, including regular inspection, removal, and installation, is essential for ensuring optimal performance and reliability of your outboard motor.

Gearcase Removal

Before we begin, it's crucial to prioritize safety. To prevent accidental starting during servicing, twist and remove all spark plug leads. Additionally, always support the outboard's weight with a suitable hoist or the tilt support bracket to avoid any personal injury.

  1. Release the Lower Shift Rod: Start by removing the pin and washer from the shift rod lever to release the lower shift rod.
    Take Off Shift Rod Screw
    Shift rod screw
  2. Remove the Trim Tab: Take note of the index mark on the gearcase that aligns with the index number of the adjustable trim tab. This will help you reinstall the trim tab in the same position. Remove the trim tab retaining screw and the trim tab itself from the gearcase.
    Index Mark, Trim Tab, Trim Tab Retaining Screw
    1. Index mark 2. Trim tab 3. Trim tab retaining screw
  3. O/S Type Gearcases: Next, remove the 3/8-16 in. screw and washer, followed by the 7/16-14 x 3.5 in. screw and washer (O Type Gearcases). Proceed to remove the four 3/8-16 x 1.75 in. screw and 7/16-14 x 3.5 in. screw (S Type Gearcases).
    O Type Gearcases
    O Type Gearcases: 1. 3/8-16 x 3.5 in. screw 2. 7/16-14 x 3.5 in. screw
    S Type Gearcases
    S Type Gearcases: 1. 3/8-16 x 1.75 in. screw 2. 7/16-14 x 3.5 in. screw
  4. Remove Gearcase Retaining Screws: Extract four 3/8-16  x 1.75 gearcase retaining screws and washers.
    Gearcase Retaining Screws Evinrude E-TEC 75hp 90hp
    1. Gearcase retaining screws
  5. Safely Remove the Gearcase Assembly: Carefully remove the gearcase assembly from the exhaust housing, ensuring not to bend the shift rod in the process.

Gearcase Installation

Again, it's important to prioritize safety during the installation process. Always support the outboard's weight with a suitable hoist or the tilt support bracket to prevent any unexpected dropping.

  1. Check Shift Rod Adjustment: Before installing the gearcase, it is crucial to check the shift rod adjustment.
  2. Lubricate the Driveshaft: Apply Moly Lube to the driveshaft splines. However, avoid coating the top surface of the driveshaft, as lubricant in this area may prevent proper seating of the driveshaft in the crankshaft.
    Lubricate the driveshaft splines.
    Lubricate the driveshaft splines.
  3. Apply Seals and Grease: Coat the inner surfaces of the lower exhaust housing seals with Adhesive 847. Place two new seals on the housing and apply Triple-Guard grease to the seals' outer surfaces. Then, position the housing onto the gearcase.
    Apply adhesive to lower exhaust housing
    1. Lower exhaust seals
  4. Proper Gearcase Alignment: Slide the gearcase into place, ensuring the following:
  • The driveshaft engages the crankshaft.
  • The water tube enters the water pump.
  • The lower inner exhaust housing installs correctly.
  • The shift rod does not turn and is positioned properly in the shift rod lever below the crankcase.
  1. Secure the Gearcase: It's important to note that new gearcase screws come treated with a thread-locking material. To ensure the correct clamping force, apply Triple-Guard grease to the threads. If reusing a previously installed screw, use a wire brush to remove any old thread-locking material or corrosion, and then lubricate the threads with Triple-Guard grease.
  • For 3/8-inch screws, tighten them to a torque of 26 to 28 ft. lbs. (35 to 38 N·m).
  • For 7/16-inch screws, tighten them to a torque of 45 to 50 ft. lbs. (61 to 68 N·m).
    Gearcase Retaining Screws Evinrude E-TEC 75hp 90hp
    1. 3/8 in. screws
    S Type Gearcases
    1. 3/8 in. screw 2. 7/16 in. screw


Maintaining the gearcase of your 75 or 90 horsepower Evinrude E-TEC outboard is an important part of ensuring its optimal performance and longevity. By following the step-by-step instructions provided in this guide, you can safely remove and install the gearcase. Remember to prioritize safety by supporting the outboard's weight and taking necessary precautions to prevent personal injury.

Always double-check the alignment of the gearcase components and ensure proper lubrication during installation. Following the recommended torque specifications for tightening the gearcase screws will help guarantee a secure fit.

By performing regular maintenance on your gearcase, you can keep your Evinrude E-TEC outboard running smoothly and efficiently, allowing you to enjoy your time on the water with confidence.

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