Thermostat Gasket – Fits Yamaha 40HP C40/CV40 Outboards (Replaces 6E9-12414-A1-00)
Thermostat Gasket – Fits Yamaha 40HP C40/CV40 Outboards (Replaces 6E9-12414-A1-00) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Thermostat Gasket – Fits Yamaha 40HP C40/CV40 Outboards (Replaces 6...
Product Details
This high-quality Thermostat Gasket ensures a perfect seal for the thermostat housing on Yamaha 2-Stroke 40HP C40 and CV40 series outboards manufactured between 1990 and 1997. It is engineered to meet or exceed original equipment specifications for a reliable, leak-free fit.
This part directly interchanges with Yamaha OEM numbers 6E9-12414-A1-00, 6E9-12414-A0-00, and 6E9-12414-01-00, as well as GLM Marine 38083.
- Installation Location: Mounts directly onto the thermostat housing.
- Material: High-density paper/composite blend designed for marine cooling systems.
- Engineered for Reliability: Built to provide a durable seal against coolant leaks.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Yamaha | 6E9-12414-A1-00 | Current OEM Part |
| Yamaha | 6E9-12414-A0-00 | Superseded by 6E9-12414-A1-00 |
| Yamaha | 6E9-12414-01-00 | Superseded by 6E9-12414-A0-00 |
| GLM Marine | 38083 | Aftermarket Replacement |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This gasket is designed for a precise fit on the following Yamaha 40HP engines.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | C40ELRQ | 40 | 2-Stroke | 1992 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40PLRQ | 40 | 2-Stroke | 1992 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40MSHQ | 40 | 2-Stroke | 1992 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40ELRR | 40 | 2-Stroke | 1993 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40PLRR | 40 | 2-Stroke | 1993 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40MSHR | 40 | 2-Stroke | 1993 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40ELRS | 40 | 2-Stroke | 1994 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40PLRS | 40 | 2-Stroke | 1994 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40MSHS | 40 | 2-Stroke | 1994 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40MLHS | 40 | 2-Stroke | 1994 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40ELRT | 40 | 2-Stroke | 1995 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40PLRT | 40 | 2-Stroke | 1995 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40MSHT | 40 | 2-Stroke | 1995 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40MLHT | 40 | 2-Stroke | 1995 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40ELRU | 40 | 2-Stroke | 1996 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40PLRU | 40 | 2-Stroke | 1996 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40MSHU | 40 | 2-Stroke | 1996 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40ELRV | 40 | 2-Stroke | 1997 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40PLRV | 40 | 2-Stroke | 1997 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40MSHV | 40 | 2-Stroke | 1997 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40ESHV | 40 | 2-Stroke | 1997 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | CV40ELD | 40 | 2-Stroke | 1990 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
| Yamaha | C40ELRP | 40 | 2-Stroke | 1991 | 6E9-12414-A1-00 | Supersedes 6E9-12414-A0-00 |
Technical Specs
- Product Type
- Thermostat Gasket
- Installation
- Thermostat Housing
- Fuel Type
- Gasoline
- Material
- Paper/Composite
- Dimensions
- 9.0 in (L) x 8.5 in (W) x 0.2 in (H)
- Operating Temperature
- Engine cooling system temperature range
- Warranty
- Standard OEM warranty
- Other Technical Attributes
- OEM replacement part
What’s in the Box
- 1 x Gasket, Cover (Replaces 6E9-12414-A1-00)
Installation Notes
- Ensure the engine is completely cool and disconnect the battery.
- Partially drain the engine coolant below the level of the thermostat housing.
- Remove the bolts securing the thermostat housing cover.
- Carefully remove the old gasket. Note the orientation of the thermostat before removing it.
- Thoroughly clean any old gasket material or residue from both the housing and cover surfaces. Avoid scoring the metal.
- Place the new gasket onto the housing surface, aligning it correctly.
- Reinstall the thermostat and housing cover, tightening the bolts to the manufacturer's specified torque in a crisscross pattern.
- Refill the cooling system, restart the engine, and carefully check for any leaks around the housing.
Troubleshooting & FAQ
How do I know if my thermostat gasket is failing?
Common signs include visible coolant leaks around the thermostat housing, engine overheating, or fluctuating temperature readings on your gauge. A visual inspection may reveal cracking or degradation of the gasket material.
Do I need to use sealant with this gasket?
This gasket is designed to be installed dry on clean, flat surfaces. Applying additional sealant is generally not recommended as it can interfere with a proper seal unless explicitly required by your engine’s service manual.
What is the recommended replacement interval?
It is best practice to replace the thermostat gasket whenever you are replacing the thermostat itself, performing major cooling system service, or if you observe any signs of leakage or material failure during inspection.
Is this compatible with models outside the listed 1990–1997 range?
We only guarantee fitment for the specific Yamaha C40 and CV40 models and years shown in the compatibility table. Part numbers and engine designs can change, so using it on other models is not advised.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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