688-45341 Straight Screw Plug Kit for Yamaha | JLM Marine

688-45341 Straight Screw Plug Kit for Yamaha Outboard Engines

This Straight Screw Plug Kit is designed to fit most Yamaha outboard engines from 40 to 300 HP. Engineered as a direct replacement for essential lower unit maintenance, this kit ensures reliable sealing for your outboard's gear oil system.

This kit directly replaces Yamaha OEM part numbers 688-45341-10-00, 90340-08002-00, and 90430-08020, providing a comprehensive solution for lower unit drain plug replacement and maintenance.

• Complete kit includes lower unit drain plug, straight screw plug, and gaskets
• Essential for routine lower unit oil changes and maintenance
• Always verify fitment by OEM part number—not solely by engine horsepower

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket sources:

Compatible Engine Models

Confirm your engine model/year in the table below. For Yamaha owners, here's a guide to help you identify your engine's serial/model: Yamaha Serial Number Guide. You can also review exploded diagrams to verify part numbers: Yamaha Parts Diagrams & Catalog.

Technical Specifications

Package Contents

This kit includes all components required for lower unit drain plug replacement:

• 1 x Lower Unit Drain Plug (688-45341)
• 1 x Straight Screw Plug (90340-08002)
• 2 x Lower Unit Oil Drain Gasket (90430-08020)

Note: The package contains all the parts shown in the product images.

Installation Guide

1. Position the outboard in an upright position and allow the engine to cool completely before beginning work.
2. Place a suitable container beneath the lower unit to catch old gear oil.
3. Remove the old drain plug and screw plug carefully, allowing all oil to drain completely.
4. Inspect the old gaskets and plugs for wear, corrosion, or damage.
5. Clean the drain and fill plug holes thoroughly, removing any debris or old gasket material.
6. Install new gaskets (90430-08020) onto the new drain plug and screw plug.
7. Hand-tighten the new lower unit drain plug (688-45341) into the bottom drain hole.
8. Fill the lower unit with the manufacturer-recommended gear oil through the fill hole until oil appears at the vent hole.
9. Install the straight screw plug (90340-08002) with a new gasket into the vent/fill hole and tighten securely.
10. Torque both plugs to Yamaha's specifications (consult your service manual for exact values).
11. Wipe away any excess oil and inspect for leaks.
12. Run the engine briefly and recheck for leaks before returning to normal operation.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my Yamaha outboard?
A: Always purchase by OEM part number, not by horsepower alone. Cross-reference your existing drain plugs with the part numbers listed (688-45341, 90340-08002, 90430-08020). While this kit fits most 40–300 HP Yamaha engines, some models may use different plug configurations.

Q: How often should I replace the drain plugs and gaskets?
A: Replace gaskets every time you perform a lower unit oil change (typically every 100 hours or annually). Drain plugs should be inspected for thread wear or corrosion and replaced if damaged or if they no longer seal properly.

Q: What are the signs that my drain plugs need replacement?
A: Look for visible oil weeping around the plugs, stripped or damaged threads, corrosion, or difficulty achieving a tight seal. If you notice milky or contaminated gear oil, inspect seals immediately and replace plugs and gaskets as needed.

Q: Can I reuse the old gaskets?
A: No. Always use new gaskets (included in this kit) each time you remove the drain or fill plugs. Reusing old gaskets can result in leaks and potential lower unit damage.

Q: What's the difference between OEM and aftermarket plug kits?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.