Yamaha - Lower Unit Assembly - Gearcase & Power Transfer - 64F-45300-00-4D

Overview

On these older 225 Yamahas, the lower unit is usually where wear starts to show first, especially if the motor’s been run hard over the years. I’ve seen plenty come in with noisy gears or rough shifting that just isn’t worth trying to patch. Dropping in a complete assembly like this gets everything back to smooth, solid operation. It’s the kind of replacement that lets you trust the motor again every time you put it in gear.

Key Features

• Complete Gearcase Assembly – Includes internal gears and housing for a full lower unit replacement.
• Smooth Power Transfer – Delivers consistent engine output to the propeller.
• Heavy-Duty Construction – Built to handle high horsepower loads and long-term marine use.
• Reliable Gear Engagement – Provides clean shifting with reduced noise and vibration.

Engine & Boat Compatibility

Fits Yamaha outboard engines in the 200 to 225 horsepower range. Commonly used on offshore boats, center consoles, and larger recreational or commercial vessels.

FAQ

Q: What are signs my lower unit needs to be replaced?
A: Grinding noise, slipping gears, water in gear oil, or difficulty shifting are common signs.

Q: Can I continue using the motor if the lower unit is making noise?
A: It’s not recommended—damage can get worse quickly and lead to complete failure.

Q: Do I need to check gear oil before using this unit?
A: Yes, always confirm it’s filled to the proper level before running.

Q: How does saltwater use affect lower units?
A: Salt can cause corrosion and wear over time, especially around seals and housing, so regular flushing helps.

Q: Is this part still current or has it been updated?
A: This assembly has been superseded by part number 64F-45300-01-8D, which is the latest version.

• Supersessions
  64F-45300-00-8D, 64F-45300-01-8D, 64F-45300-01-8D