Lower Gearcase Oil Drain Gasket for Yamaha Outboard Motors – Yamaha 90430-08003-00 and 90430-08020-00 Applications
Lower Gearcase Oil Drain Gasket for Yamaha Outboard Motors – Yamaha 90430-08003-00 and 90430-08020-00 Applications is backordered and will ship as soon as it is back in stock.
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Lower Gearcase Oil Drain Gasket for Yamaha Outboard Motors – Yamaha...
Lower Gearcase Oil Drain Gasket for Yamaha Outboard Motors – Yamaha 90430-08003-00 and 90430-08020-00 Applications is backordered and will ship as soon as it is back in stock.
Product Details
This Lower Gearcase Oil Drain Gasket is used to seal a Yamaha outboard lower-unit drain, fill, or vent screw during gear-oil service. A properly fitted new gasket helps reduce oil leakage and helps prevent water from entering the gearcase through the screw sealing surface.
Cataloged Yamaha applications include both older 2-stroke and later 4-stroke outboard models. The references documented for this gasket include Yamaha 90430-08003-00 and Yamaha 90430-08020-00. Always compare the part number, screw, sealing surface, and service-manual application for your specific engine before ordering.
- Designed for use in marine lower-unit gear-oil service.
- Use a new gasket when reinstalling the drain or fill screw rather than relying on a previously compressed gasket.
- Many lower-unit services require two gaskets—one for the lower drain screw and one for the upper fill or vent screw—but confirm the quantity required for your engine.
Part Number Matrix
The following are customer-facing manufacturer or aftermarket reference numbers associated with documented Yamaha applications. They should be used as application references, not as a guarantee of interchange across every Yamaha model.
| Brand | Part Number | Reference Type |
|---|---|---|
| Yamaha | 90430-08003-00 | Documented Yamaha gasket reference |
| Yamaha | 90430-08020-00 | Documented Yamaha gasket reference |
| Yamaha | 90430-08021-00 | Reference supplied for this listing; verify by engine model |
| Yamaha | 90430-08801-00 | Reference supplied for this listing; verify by engine model |
| Yamaha | 604-45342-00-00 | Reference supplied for this listing; verify by engine model |
| Sierra | 18-4698 | Aftermarket reference supplied for this listing |
Engine & Model Compatibility
Verified catalog occurrences show the Yamaha gasket reference 90430-08003-00 in the lower casing drive diagrams for the following 2016 four-stroke models, among other catalog entries:
| Brand | Model | Rated HP | Stroke | Year | Documented Part No. | Catalog Location |
|---|---|---|---|---|---|---|
| Yamaha | F15LEHA, F15LMHA, F15LPHA, F15SEHA | 15 | 4-Stroke | 2016 | 90430-08003-00 | Lower casing drive and service-parts diagrams |
| Yamaha | F115JB, F115LB, F115XB | 115 | 4-Stroke | 2016 | 90430-08003-00 | Lower casing drive and service-parts diagrams |
| Yamaha | F150JB, F150LB, F150XB | 150 | 4-Stroke | 2016 | 90430-08003-00 | Lower casing drive and service-parts diagrams |
| Yamaha | Selected 1984 models including 2SK, 15ELN, 25ELN, 40ELN, 115ETLN, 150ETLN, 175ETLN and 200ETLN | 2–200 | 2-Stroke | 1984 | 90430-08020-00 | Lower drive diagrams |
These examples do not establish universal fitment for every Yamaha outboard, every horsepower rating, or every production year. Confirm the exact engine model and applicable part number before installation.
Technical Specs
- Product Type
- Lower-unit drain, fill, or vent screw gasket
- Installation
- Replace during lower-unit gear-oil service
- Fitting Type
- Crush washer/gasket
- Material
- Fiber/composite gasket material as supplied
- Application
- Yamaha outboard lower gearcase service
- Quantity
- 1 gasket
- Reusability
- Single-use service gasket; replace after removal
What’s in the Box
- 1 x Lower gearcase oil drain gasket
One gasket is included. A complete lower-unit oil change may require additional gaskets for other screw locations; check your engine's service procedure before ordering.
Installation Notes
- Place a suitable drain pan beneath the lower unit.
- Remove the lower drain screw and then the upper fill or vent screw according to the engine manufacturer's service procedure.
- Inspect the magnetic drain screw and the drained lubricant for unusual metal particles or water contamination.
- Remove and discard the old gasket from each screw being serviced.
- Clean the screw threads and sealing surfaces so they are free of old gasket material, dirt, and excess oil.
- Install a new gasket on the applicable screw and reinstall it using the manufacturer's specified torque. Do not overtighten.
- Fill the gearcase with the recommended lubricant through the lower fill opening or as directed by the service manual.
- Install the upper screw with a new gasket where required, then tighten to the specified torque.
- Wipe the area clean and inspect for leaks after servicing.
Troubleshooting & FAQ
How often should this gasket be replaced?
Replace it whenever the applicable drain, fill, or vent screw is removed for gear-oil service. Reusing a compressed gasket can increase the risk of leakage.
How many gaskets are needed for one engine service?
The required quantity depends on the engine and service procedure. Many lower-unit oil changes use one gasket at the drain screw and one at the upper fill or vent screw, so confirm the requirement for your specific model.
What are the signs of a failing lower-unit gasket?
Possible signs include oil seepage around a screw, lubricant dripping from the lower unit, or milky lubricant that may indicate water contamination. Inspect the gasket, screw, and sealing surface together.
Will this fit my Mercury, Johnson, or another brand outboard?
This listing is intended for documented Yamaha applications. Other brands may use different gasket dimensions or materials, so do not substitute it without confirmed application information.
Is the gasket reusable?
No. Treat it as a single-use service gasket and install a new one after removal.
Is this an OEM component?
This listing is for an aftermarket replacement gasket. Yamaha part numbers are shown as application references only; Yamaha does not manufacture or sell this aftermarket item.
How should I confirm compatibility?
Match your engine brand, model, year, stroke, and applicable screw or gearcase diagram with the reference number before ordering. The documented 90430-08003-00 and 90430-08020-00 applications are not presented as universal interchange coverage for every Yamaha outboard.
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Warranty and returns
Warranty and return eligibility are governed by the store's current policies. Contact support with your order details if you receive a damaged or incorrect item.
Safety & Important Information
- Confirm the engine model, year, stroke, and applicable manufacturer reference before purchase.
- Do not treat this gasket as universal across all Yamaha outboards solely because the engine is Yamaha-branded.
- Use the lubricant type and tightening torque specified for your engine.
- Inspect the drained lubricant for water or metal contamination and address any underlying gearcase problem before returning the engine to service.
- Professional installation is recommended when the correct application or service procedure is uncertain.
About Sea Sierra
- Pro-Grade Standards — We supply marine replacement parts selected for dependable service in real-world operating conditions.
- Global Fulfillment — Delivery options and estimated transit times are provided at checkout for the destination country.
- Manufacturer-Direct Value — We aim to provide practical replacement parts with clear application information.
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