# 90430-08003 Yamaha Gearbox Drain Gasket | Genuine OEM Yamaha Outboard Part

🔧 Product Description

  

Genuine Yamaha Gearcase Drain and Vent Screw Gasket - Part Number: 90430-08003

  

A genuine Yamaha fibre sealing washer for lower-unit gear-oil drain, fill and vent screws.

  

The gasket seals beneath the screw head and should normally be replaced whenever the plug is removed to prevent lubricant loss or water entry.

  

⚙️ Key Features

  

• Genuine Yamaha OEM gearcase screw gasket

• Correct current Yamaha part number 90430-08003

• Supersedes earlier washer 90430-08020

• Used on Yamaha lower-unit drain and vent screws

• Two washers commonly required during a gear-oil change

  

🔄 Supersession & Cross Reference

  

OEM Supersession Chain:

  

• 90430-08003 → Supersedes 90430-08020

• 90430-08020 earlier OEM gearcase gasket reference

  

OEM / Related Numbers:

  

• 90430-08003

• 90430-08003-00

• 90430-08020

• Yamaha gear-oil drain-plug washer

• Yamaha vent-plug sealing gasket

  

Aftermarket / Verified Equivalents:

  

• Aftermarket Yamaha-pattern black fibre drain-plug washer

• Replacement gasket supplied in Yamaha-pattern gear-oil service kits

  

🚤 Compatibility

  

Commonly used on:

  

• Yamaha outboard lower-unit drain and vent screws

• Gearcase lubricant servicing

  

Typically suits:

  

• Engine models:

• Yamaha portable outboards

• Yamaha mid-range outboards

• Yamaha V6 and V8 high-horsepower outboards

• Yamaha two-stroke, HPDI, four-stroke, VMAX SHO and XTO gearcases using the matching drain screw

• Conventional and counter-rotation Yamaha lower units

  

• HP Range: Applicable Yamaha outboards from small portable engines through high-horsepower models

• System Type: Lower-unit lubricant drain, fill and vent screw

• Service Quantity: Commonly two gaskets per gear-oil change.

  

🔌 Function

  

The gasket forms a fluid-tight seal beneath the drain or vent screw, retaining gear lubricant and preventing water intrusion.

  

Common signs of failure:

  

• Gear oil around the screw

• Milky or water-contaminated lubricant

• Washer is flattened, cracked or missing

• Gearcase fails pressure testing at the plug

• Leakage begins after an oil change

  

📦 Condition

  

• Genuine Yamaha part

• Brand new

• Supplied in original or equivalent packaging

## Details

- **Price:** 3.7 AUD
- **Vendor:** Yamaha
- **Tags:** Yamaha Marine Parts | Outboard Engine Parts & Components

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 3.70 AUD | In stock |

## Images

- 90430-08003 Yamaha Gearbox Drain Gasket | Genuine OEM Yamaha Outboard Part

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/90430-08003-gearbox-drain-gasket)
> Updated: 2026-07-11