6AU-14301-40 Thermostat for Yamaha T9.9G F9.9F | JLM Marine

6AU-14301-40 Thermostat for Yamaha T9.9G F9.9F | JLM Marine

This high-quality aftermarket thermostat is engineered to fit Yamaha 9.9HP outboard engines, including the T9.9G and F9.9F series. Designed to regulate engine temperature efficiently, this thermostat ensures optimal performance and longevity for your outboard motor across a wide range of operating conditions.

This thermostat directly replaces Yamaha OEM part numbers 6AU-14301-40, 6AU-14301-41, 6AU-14301-30, and 6AU-14301-31, providing reliable compatibility with multiple Yamaha 9.9HP models from 2006 and later.

• Direct fit replacement for Yamaha 9.9HP T9.9G and F9.9F series engines
• Ensures proper engine cooling and prevents overheating
• Compatible with models from 2006 and later production years

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.

Technical Specifications

Package Contents

• 1 × Thermostat

Installation Guide

1. Ensure the engine is completely cool and disconnect the battery before starting work. Gather necessary tools including screwdrivers, wrenches, and a drain pan.
2. Locate the thermostat housing on your Yamaha 9.9HP engine, typically positioned near the cylinder head. Consult your engine's service manual for exact location if needed.
3. Drain the cooling system by removing the drain plug or hose to prevent coolant spillage. Collect the coolant in a suitable container.
4. Remove the bolts or fasteners securing the thermostat housing cover. Carefully lift the cover away from the housing.
5. Remove the old thermostat from the housing, taking note of its orientation and position. Clean any old gasket material or debris from the housing and cover surfaces.
6. Install the new thermostat in the same orientation as the old unit, ensuring the spring side faces toward the engine block. Position any gasket or O-ring according to manufacturer specifications.
7. Reinstall the thermostat housing cover and tighten the bolts evenly to the proper torque specification. Avoid over-tightening to prevent cracking.
8. Refill the cooling system with the appropriate type and amount of coolant as specified in your owner's manual. Check for proper coolant level.
9. Reconnect the battery and start the engine, allowing it to reach normal operating temperature. Monitor for leaks around the thermostat housing.
10. Check coolant level after the engine has warmed up and cooled down, topping off as necessary. Verify that the engine maintains proper operating temperature during operation.

Troubleshooting & FAQ

Q: How do I confirm this thermostat fits my Yamaha engine?
A: Check the compatible engine models table above to verify your specific model and year. You can also cross-reference your existing thermostat part number with the OEM numbers listed (6AU-14301-40, 6AU-14301-41, 6AU-14301-30, 6AU-14301-31).

Q: How often should I replace the thermostat on my outboard?
A: Thermostats should be inspected annually and replaced every 2-3 years or sooner if you notice signs of overheating, erratic temperature readings, or poor engine performance. Regular replacement helps prevent costly engine damage from cooling system failures.

Q: What are the signs that my thermostat is failing?
A: Common symptoms include engine overheating, unusually low operating temperatures, fluctuating temperature gauge readings, or steam from the engine compartment. If you notice any of these issues, inspect and replace the thermostat immediately.

Q: What's the difference between this aftermarket thermostat and the OEM part?
A: This aftermarket thermostat is manufactured to meet OEM specifications and performance standards at a more competitive price point. It provides the same fit, function, and reliability as the original Yamaha part while offering better value.

Q: Is this an OEM or aftermarket part?
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.