Thermostat Cover Gasket – Fits Yamaha 25-30HP 2-Stroke Outboards (Replaces 655-12414-A1-00)
Thermostat Cover Gasket – Fits Yamaha 25-30HP 2-Stroke Outboards (Replaces 655-12414-A1-00) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Free standard shipping on all orders under 1 KG
Thermostat Cover Gasket – Fits Yamaha 25-30HP 2-Stroke Outboards (R...
Product Details
This aftermarket Thermostat Cover Gasket provides a secure seal for the thermostat housing on Yamaha 25–30 HP 2-stroke outboard engines (C25, C30 series) manufactured between 1992 and 1997.
It serves as a direct replacement for Yamaha OEM part numbers 655-12414-A1-00 and its superseded predecessor, 655-12414-00-00.
- Engineered for direct-fit installation.
- Designed to withstand demanding marine environments.
- Includes one gasket per package.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket providers.
| Brand | Part Number | Notes |
|---|---|---|
| Yamaha (OEM) | 655-12414-A1-00 | Current OEM part number. |
| Yamaha (OEM) | 655-12414-00-00 | Superseded by 655-12414-A1-00. |
| Sierra Marine | 18-0232 | Aftermarket replacement. |
Engine & Model Compatibility
Confirm your engine model and year in the table below.
This gasket is compatible with the following Yamaha outboard models:
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | C25ELRQ | 25 | 2-Stroke | 1992 | 655-12414-A1-00 | |
| Yamaha | C25MSHQ | 25 | 2-Stroke | 1992 | 655-12414-A1-00 | |
| Yamaha | C30ELRQ | 30 | 2-Stroke | 1992 | 655-12414-A1-00 | |
| Yamaha | C25ELHR | 25 | 2-Stroke | 1993 | 655-12414-A1-00 | |
| Yamaha | C25ELRR | 25 | post2-Stroke | 1993 | 655-12414-A1-00 | |
| Yamaha | C25MLHR | 25 | 2-Stroke | 1993 | 655-12414-A1-00 | |
| Yamaha | C25MSHR | 25 | 2-Stroke | 1993 | 655-12414-A1-00 | |
| Yamaha | C30ELRR | 30 | 2-Stroke | 1993 | 655-12414-A1-00 | |
| Yamaha | C25ELHS | 25 | 2-Stroke | 1994 | 655-12414-A1-00 | |
| Yamaha | C25ELRS | 25 | 2-Stroke | 1994 | 655-12414-A1-00 | |
| Yamaha | C25MLHS | 25 | 2-Stroke | 1994 | 655-12414-A1-00 | |
| Yamaha | C25MSHS | 25 | 2-Stroke | 1994 | 655-12414-A1-00 | |
| Yamaha | C30ELRS | 30 | 2-Stroke | 1994 | 655-12414-A1-00 | |
| Yamaha | C30MLHS | 30 | 2-Stroke | 1994 | 655-12414-A1-00 | |
| Yamaha | C25ELHT | 25 | 2-Stroke | 1995 | 655-12414-A1-00 | |
| Yamaha | C25ELRT | 25 | 2-Stroke | 1995 | 655-12414-A1-00 | |
| Yamaha | C25MLHT | 25 | 2-Stroke | 1995 | 655-12414-A1-00 | |
| Yamaha | C25MSHT | 25 | 2-Stroke | 1995 | 655-12414-A1-00 | |
| Yamaha | C30ELRT | 30 | 2-Stroke | 1995 | 655-12414-A1-00 | |
| Yamaha | C30ERT | 30 | 2-Stroke | 1995 | 655-12414-A1-00 | |
| Yamaha | C25ELHU | 25 | 2-Stroke | 1996 | 655-12414-A1-00 | |
| Yamaha | C25ELRU | 25 | 2-Stroke | 1996 | 655-12414-A1-00 | |
| Yamaha | C25MLHU | 25 | 2-Stroke | 1996 | 655-12414-A1-00 | |
| Yamaha | C25MSHU | 25 | ted2-Stroke | 1996 | 655-12414-A1-00 | |
| Yamaha | C30ELRU | 30 | 2-Stroke | 1996 | 655-12414-A1-00 | |
| Yamaha | C25ELHV | 25 | 2-Stroke | 1997 | 655-12414-A1-00 | |
| Yamaha | C25ELRV | 25 | 2-Stroke | 1997 | 655-12414-A1-00 | |
| Yamaha | C25MLHV | 25 | 2-Stroke | 1997 | 655-12414-A1-00 | |
| Yamaha | C25MSHV | 25 | 2-Stroke | 1997 | 655-12414-A1-00 | |
| Yamaha | C30ELRV | 30 | 2-Stroke | 1997 | 655-12414-A1-00 | |
| Yamaha | WR500Q | - | 2-Stroke | 1992 | 655-12414-A1-00 | Waverunner model |
| Yamaha | WR500R | - | 2-Stroke | 1993 | 655-12414-A1-00 | Waverunner model |
Technical Specs
- Product Type
- Thermostat Cover Gasket
- Installation
- Direct replacement
- Dimensions
- 4.0 × 5.13 × 1.06 inches
- Weight
- 1.76 ounces (50 grams)
- OEM Part Number
- 655-12414-A1-00
- Supersedes
- 655-12414-00-00
- Compatible Engines
- Yamaha 25HP and 30HP 2-stroke outboards
What’s in the Box
- 1 × Thermostat Cover Gasket (655-12414-A1-00)
Installation Notes
- Ensure the engine is off and cool. Disconnect the battery.
- Locate the thermostat housing on the engine block.
- Unscrew the bolts securing the thermostat cover and remove the cover.
- Carefully remove the old gasket, taking note of its orientation. Clean both mating surfaces thoroughly, removing all old gasket material and corrosion.
- Place the new gasket onto the housing, ensuring it is correctly aligned.
- Reinstall the thermostat cover and tighten the bolts to the manufacturer's specified torque in a crisscross pattern.
- Reconnect the battery, start the engine, and check for any leaks around the housing.
Troubleshooting & FAQ
How do I confirm this gasket fits my engine?
This gasket is designed for Yamaha C25 and C30 series 2-stroke outboards from 1992–1997. The most reliable method is to match your engine's model number and year against our compatibility table. If you are unsure, cross-reference the OEM part number (655-12414-A1-00) with your engine's service manual.
What are signs of a failing thermostat gasket?
Common symptoms include visible coolant (water) leaks around the thermostat housing, engine overheating alarms, or steam coming from the engine cowling. A damaged or brittle gasket can fail to create a proper seal, leading to loss of cooling efficiency.
How often should this gasket be replaced?
It is best practice to replace the thermostat cover gasket every time the thermostat is serviced or replaced. Gaskets can compress, harden, and become brittle over time, making them a single-use part. Proactive replacement during routine cooling system maintenance can prevent unexpected leaks.
Is this part compatible with Waverunner models?
Yes, records indicate this gasket also fits certain Yamaha Waverunner models, specifically the WR500Q (1992) and WR500R (1993). However, always verify the part number against your personal watercraft's service manual before ordering.
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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