Cylinder Head Gasket – Fits Yamaha 40HP 2-Stroke (Replaces 6F5-11181-A1, 6F5-11181-A2)
Cylinder Head Gasket – Fits Yamaha 40HP 2-Stroke (Replaces 6F5-11181-A1, 6F5-11181-A2) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Cylinder Head Gasket – Fits Yamaha 40HP 2-Stroke (Replaces 6F5-1118...
Product Details
This aftermarket Cylinder Head Gasket for Yamaha 40HP 2-Stroke engines is engineered for a precise fit on various models, including the E40G, E40J, E40GMH, E40JMH, 40GWH, and 40JWH series (_2003 and compatible years_). It is also designed to fit select Mercury 40HP 2-stroke outboard engines, offering a reliable seal for optimal engine compression and performance.
It serves as a direct cross-reference for Yamaha part numbers 6F5-11181-A1, 6F5-11181-A2, and 6F5-11181-A200, and is also interchangeable with Mercury part 27-11745M.
- Designed for installation on the engine cylinder head.
- Constructed from a durable composite material suitable for marine gasoline (petrol) engines.
- Identified as position #22 in standard exploded view diagrams for easy reference during service.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Yamaha | 6F5-11181-A1 |
| Yamaha | 6F5-11181-A2 |
| Yamaha | 6F5-11181-A200 |
| Mercury | 11745 |
| Mercury | 27-11745M |
Engine & Model Compatibility
Confirm your engine model and year in the table below to ensure accurate fitment.
For Yamaha owners, please verify that your E40, 40G, 40J, 40K, or Enduro 40 series engine matches the specifications listed.
For Mercury owners, this part is compatible with select 40HP 2-stroke models that specify OEM part numbers 11745 or 27-11745M. Please verify your engine's required part number.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | E40GMH | 40 | 2-Stroke | 2003 | 6F5-11181-A1, 6F5-11181-A2 | |
| Yamaha | E40JMH | 40 | 2-Stroke | 2003 | 6F5-11181-A1, 6F5-11181-A2 | |
| Yamaha | 40GWH | 40 | 2-Stroke | 6F5-11181-A1, 6F5-11181-A2 | ||
| Yamaha | 40JWH | 40 | 2-Stroke | 6F5-11181-A1, 6F5-11181-A2 | ||
| Yamaha | 40K | 40 | 2-Stroke | 6F5-11181-A1, 6F5-11181-A2 | W40 (W/MARATHON) | |
| Yamaha | Enduro 40 | 40 | 2-Stroke | 6F5-11181-A1, 6F5-11181-A2 |
Technical Specs
- Product Type
- Cylinder Head Gasket
- Installation
- Engine cylinder head
- Fuel Type
- Gasoline (Petrol)
- Material
- Composite
- Dimensions
- 25.5cm L x 15.5cm W x 0.2cm H
- Application
- Yamaha 40HP 2-Stroke outboard engines
- OEM Part Number
- 6F5-11181-A1, 6F5-11181-A2, 6F5-11181-A200
- Other Technical Attributes
- Position: #22 in exploded view diagram
What’s in the Box
- 1 x Cylinder Head Gasket (Replaces 6F5-11181-A2)
Installation Notes
- Ensure the engine is completely cool and disconnect the battery.
- Drain the engine coolant to a suitable container to prevent spills.
- Remove the cylinder head cover and any other components obstructing access to the head.
- Carefully loosen and remove the cylinder head bolts in the reverse order of the tightening sequence specified in your service manual.
- Lift the cylinder head off the engine block and remove the old gasket.
- Thoroughly clean the mating surfaces of both the cylinder head and the engine block. Remove all traces of old gasket material, sealant, and carbon buildup.
- Position the new gasket correctly on the engine block, ensuring all holes and passages align perfectly. Do not use sealant unless explicitly required by the manufacturer.
- Carefully place the cylinder head back onto the block and install new or inspected head bolts, tightening them to the specified torque in the correct sequence.
Troubleshooting & FAQ
How do I know if this gasket will fit my Yamaha 40HP engine?
This gasket fits Yamaha E40G/J/GMH/JMH series and other 40HP 2-stroke models from 2003 and compatible years. Always cross-reference your engine's current part number with those listed on our product page: 6F5-11181-A1, 6F5-11181-A2, or 6F5-11181-A200.
What are the signs of a failing cylinder head gasket?
Common symptoms include engine overheating, a noticeable loss of power or compression, milky-looking oil (indicating coolant contamination), or excessive white smoke from the exhaust, which suggests coolant is being burned in the cylinders.
Is any sealant required when installing this gasket?
This gasket is designed to be installed dry. Unless your engine's official service manual explicitly states otherwise, you should not use any additional sealants, as they can interfere with a proper seal and cause premature failure.
Can I reuse my old cylinder head bolts?
It is strongly recommended to use new cylinder head bolts during installation. Head bolts are often torque-to-yield, meaning they permanently stretch when tightened and may not provide the correct clamping force if reused, leading to leaks or gasket failure.
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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