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 HP to 300 HP. It provides essential lower unit drain and screw plug components for routine maintenance and oil changes on your Yamaha outboard motor.

Direct Replacements: This kit replaces Yamaha OEM part numbers 688-45341-10-00, 688-45341, 90340-08002-00, 90340-08002, 90430-08020, and 90430-08003.

• Complete kit includes lower unit drain plug, straight screw plug, and two oil drain gaskets
• Designed for lower unit oil maintenance on Yamaha outboards
• Important: Always purchase by part number, not by engine horsepower alone

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

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.

Fits: Most (but not all) Yamaha outboard engines rated 40 HP to 300 HP. Always verify by part number before purchasing.

Technical Specifications

Package Contents

This kit includes all components shown in the product images:

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

Installation Guide

1. Position your outboard in an upright, vertical position and allow the engine to cool completely before beginning any lower unit maintenance.
2. Place a suitable drain pan beneath the lower unit to catch the old gear oil.
3. Using the appropriate socket or wrench, carefully remove the old drain plug from the lower unit drain hole.
4. Remove the upper vent/fill screw plug to allow proper drainage and airflow.
5. Allow all old lower unit oil to drain completely; inspect the oil for metal shavings, water contamination, or unusual discoloration.
6. Clean the magnetic drain plug to remove any metal debris, then wipe the drain hole area clean.
7. Install a new gasket (90430-08020) onto the lower drain plug (688-45341).
8. Thread the lower drain plug by hand first to avoid cross-threading, then tighten to the manufacturer's specified torque.
9. Refill the lower unit with the appropriate marine gear oil through the lower drain hole until oil appears at the upper vent hole.
10. Install a new gasket onto the upper straight screw plug (90340-08002) and install it hand-tight, then torque to specification.
11. Wipe away any excess oil and inspect both plugs for proper seating and signs of leakage.
12. Run the engine briefly and recheck both plugs; retighten if necessary and monitor for leaks during your next outing.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my specific Yamaha outboard?
A: Always verify fitment by matching the OEM part numbers (688-45341, 90340-08002, 90430-08020) with your engine's service manual or parts diagram. Do not rely solely on horsepower rating, as some models may use different plug configurations.

Q: How often should I replace the lower unit drain plugs and gaskets?
A: Replace the gaskets every time you perform a lower unit oil change (typically every 100 hours or annually). Inspect the drain plugs for wear, corrosion, or stripped threads and replace as needed.

Q: What should I do if I notice metal shavings on the magnetic drain plug?
A: Small amounts of fine metal dust are normal and indicate regular gear wear. However, large chunks, excessive debris, or a sudden increase in metal particles may indicate gear damage and should be inspected by a qualified marine technician immediately.

Q: Can I reuse the old gaskets when reinstalling the drain plugs?
A: No, always use new gaskets with each oil change. Reusing old gaskets can result in improper sealing, leading to gear oil leaks and potential lower unit damage.

Q: What's the difference between OEM and aftermarket plugs and gaskets?
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.