Cylinder Head Gasket – Fits Tohatsu/Nissan 9.9HP, 15HP, 18HP Outboard Motors (Replaces 351-01005-0)
Cylinder Head Gasket – Fits Tohatsu/Nissan 9.9HP, 15HP, 18HP Outboard Motors (Replaces 351-01005-0) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Cylinder Head Gasket – Fits Tohatsu/Nissan 9.9HP, 15HP, 18HP Outboa...
Product Details
This aftermarket Cylinder Head Gasket creates a secure seal between the engine block and cylinder head on a range of Tohatsu, Nissan, and Mercury outboard motors. It is specifically designed for Tohatsu/Nissan 9.9HP, 15HP, and 18HP 2-stroke models, including the M9.9D/D2, M15D/D2, and M18E2 series, as well as select 2-cylinder international Mercury 9.9HP models that utilize Tohatsu powerheads.
This part is a direct replacement for Tohatsu/Nissan part numbers 351-01005-0, 351-01005-1, 351010050M, and 351010051M, and Mercury interchange references 27-803663018 and 803663034.
- Engineered for 2-cylinder engine block configurations.
- Installs at the engine cylinder head interface.
- Designed for use with standard gasoline fuel systems.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Superseded By |
|---|---|---|
| Tohatsu / Nissan | 351-01005-0 | 351-01005-1 |
| Tohatsu / Nissan | 351010050M | 351010051M |
| Tohatsu / Nissan | 351-01005-1 | |
| Tohatsu / Nissan | 351010051M | |
| Mercury | 27-803663018 | |
| Mercury | 803663034 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Tohatsu & Nissan Owners: This part fits a wide range of 9.9HP, 15HP, and 18HP 2-stroke and 4-stroke models from the early 2000s. Please check your specific model and year.
For Mercury Owners: This part is known to fit certain 9.9HP 2-cylinder international models which use a Tohatsu powerhead. Cross-reference your OEM part number for confirmation.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Tohatsu | M9.9D | 9.9 | 2-Stroke | 2002–2003 | 351-01005-0 | Superseded by 351-01005-1 |
| Tohatsu | M9.9D2 | 9.9 | 2-Stroke | 2002–2003 | 351-01005-0 | Superseded by 351-01005-1 |
| Tohatsu | M15C | 15 | 2-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Tohatsu | M15D2 | 15 | 2-Stroke | 2002–2003 | 351-01005-0 | Superseded by 351-01005-1 |
| Tohatsu | M18D | 18 | 2-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Tohatsu | M18E2 | 18 | 4-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Nissan | NS9.9B2 | 9.9 | 2-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Nissan | NS9.9C | 9.9 | 2-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Nissan | NS9.9D | 9.9 | 2-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Nissan | NS9.9D2 | 9.9 | 2-Stroke | 2002–2003 | 351-01005-0 | Superseded by 351-01005-1 |
| Nissan | NS15B2 | 15 | 2-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Nissan | NS15C | 15 | 2-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Nissan | NS15D | 15 | 2-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Nissan | NS15D2 | 15 | 2-Stroke | 2002–2003 | 351-01005-0 | Superseded by 351-01005-1 |
| Nissan | NS18C2 | 18 | 4-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Nissan | NS18D | 18 | 2-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Nissan | NS18E | 18 | 2-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Nissan | NS18E2 | 18 | 4-Stroke | 2002 | 351-01005-0 | Superseded by 351-01005-1 |
| Mercury | 9.9HP | 9.9 | 2-Stroke | 27-803663018 | 2-cylinder international models |
Technical Specs
- Product Type
- Cylinder Head Gasket
- Application
- Engine cylinder head interface
- Engine Configuration
- For 2-cylinder engine block configurations
- Housing Material
- Paper-based gasket material
- Product Dimensions
- 25.5 cm x 14.5 cm x 0.3 cm
- Weight
- 50g (0.11 lb)
What’s in the Box
- 1 x Cylinder Head Gasket (Replaces 351-01005-0/351-01005-1)
Installation Notes
- Ensure the engine is off and cool. Disconnect the battery and drain the cooling system completely.
- Carefully remove components obstructing access to the cylinder head, such as the engine cover, ignition coils, and fuel lines. Keep track of all hardware.
- Loosen and remove the cylinder head bolts in the reverse order of the manufacturer's tightening sequence. Lift the cylinder head off the block.
- Remove the old gasket. Thoroughly clean the mating surfaces on both the engine block and the cylinder head. Use a plastic scraper and appropriate solvent to remove all residue without gouging the metal.
- Position the new gasket on the engine block, ensuring all bolt holes and fluid passages align perfectly. Do not use any sealant unless explicitly required by the service manual.
- Carefully place the cylinder head back onto the block and gasket. Reinstall the head bolts and tighten them in stages, following the specific torque sequence and values outlined in your engine's service manual.
- Re-install all previously removed components, reconnect the battery, refill the cooling system, and check all fluid levels before starting the engine.
Troubleshooting & FAQ
How do I know if my cylinder head gasket is failing?
Key symptoms include engine overheating, a noticeable loss of power or compression, milky or frothy engine oil (indicating coolant contamination), white smoke from the exhaust, or visible coolant leaks around the cylinder head seam.
Is this gasket compatible with my specific engine?
This gasket is designed for the Tohatsu and Nissan 9.9HP, 15HP, and 18HP 2-stroke models listed in the compatibility table, such as the M9.9D, M15D, and M18E2 series. It also fits certain international Mercury 9.9HP engines using a Tohatsu powerhead. Always verify your engine's model, year, and OEM part number against our tables before ordering.
What is the correct installation orientation for this gasket?
The gasket is precision-cut and will only align correctly in one orientation. Match the bolt holes and passages on the gasket with those on the engine block surface before placing the cylinder head. There is no top or bottom, but the shape is asymmetrical to ensure a unique fit.
What's the difference between OEM and this aftermarket part?
This listing is for a high-quality aftermarket replacement part, not an OEM component. It is engineered to meet or exceed OEM-level specifications for fit, material quality, and performance. Our parts are manufactured in an ISO 9002 certified facility and are batch-inspected to ensure reliability and consistency.
How fast is shipping and what does it cost?
We ship worldwide quickly, with typical transit times of 5–15 days for most regions. Standard shipping is free for all orders. Expedited shipping options, if available for your location, will be presented at checkout.
What is the warranty and return policy?
This part is covered by a 1-year warranty against manufacturing defects under normal marine use. If you encounter an issue, please contact our support team with your order details. Returns are accepted within our standard window for unused items in their original condition. See our official policy page or reach out for detailed 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 quality control.
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