Cylinder Head Gasket – Fits Tohatsu/Nissan 9.9HP–18HP (Replaces 350-01005-0, 350-01005-1)
Cylinder Head Gasket – Fits Tohatsu/Nissan 9.9HP–18HP (Replaces 350-01005-0, 350-01005-1) 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 Tohatsu/Nissan 9.9HP–18HP (Replaces 350...
Product Details
This aftermarket Cylinder Head Gasket is engineered for a precise fit on a range of Tohatsu, Nissan, Mercury, and Mariner 2-stroke outboard engines. It is designed for 9.9HP, 15HP, and 18HP models, including Tohatsu/Nissan M9.9, M15, M18 (2002 and earlier), M18E2 (2003), and Mercury/Mariner 18HP engines with serial number 0N001590 and up.
It serves as a direct replacement for Tohatsu/Nissan part numbers 350-01005-0 and 350-01005-1, and Mercury equivalents 27-803663, 27-8M0141796, 803663, 803663019, and 8M0141796.
- Ensures a reliable seal for 2-cylinder engine configurations.
- Installation is a direct replacement for the original part.
- Constructed from a durable paper/rubber composite to meet engine requirements.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Tohatsu / Nissan | 350-01005-0 |
| Tohatsu / Nissan | 350-01005-1 |
| Mercury / Mariner | 27-803663 |
| Mercury / Mariner | 27-8M0141796 |
| Mercury / Mariner | 803663 |
| Mercury / Mariner | 803663019 |
| Mercury / Mariner | 8M0141796 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Tohatsu and Nissan engines, this part fits various 9.9HP to 18HP 2-stroke models, primarily manufactured up to 2003.
For Mercury and Mariner outboards, this gasket is compatible with specific 18HP 2-stroke models based on serial number.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Tohatsu | M9.9D | 9.9 | 2-Stroke | Up to 2002 | 350-01005-0 | Assembly Kit and Cylinder/Crankcase Assembly |
| Tohatsu | M9.9B2 | 9.9 | 2-Stroke | Up to 2002 | 350-01005-0 | Cylinder/Crankcase Assembly |
| Tohatsu | M9.9D2 | 9.9 | 2-Stroke | Up to 2002 | 350-01005-0 | Cylinder/Crankcase Assembly |
| Tohatsu | M15D | 15 | 2-Stroke | Up to 2002 | 350-01005-0 | Assembly Kit and Cylinder/Crankcase Assembly |
| Tohatsu | M18E | 18 | 2-Stroke | Up to 2002 | 350-01005-0 | Assembly Kit and Cylinder/Crankcase Assembly |
| Tohatsu | M18E2 | 18 | 2-Stroke | 2003 | 350-01005-0 | Cylinder/Crankcase Assembly |
| Nissan | NS9.9D | 9.9 | 2-Stroke | Up to 2002 | 350-01005-0 | Assembly Kit and Cylinder/Crankcase Assembly |
| Nissan | NS9.9B2 | 9.9 | 2-Stroke | Up to 2002 | 350-01005-0 | Cylinder/Crankcase Assembly |
| Nissan | NS9.9D2 | 9.9 | 2-Stroke | Up to 2002 | 350-01005-0 | Cylinder/Crankcase Assembly |
| Nissan | NS15D | 15 | 2-Stroke | Up to 2002 | 350-01005-0 | Assembly Kit and Cylinder/Crankcase Assembly |
| Nissan | NS18E | 18 | 2-Stroke | Up to 2002 | 350-01005-0 | Assembly Kit and Cylinder/Crankcase Assembly |
| Nissan | NS18E2 | 18 | 2-Stroke | 2003 | 350-01005-0 | Cylinder/Crankcase Assembly |
| Mercury | 18HP | 18 | 2-Stroke | 27-803663 | Serial number 0N001590 and up |
Technical Specs
- Product Type
- Cylinder Head Gasket
- Installation
- Direct replacement
- Housing Material
- Paper/Rubber
- Housing Color
- Black
- Engine Configuration
- 2-Cylinder
- Piston Bore Size
- 60mm
- Product Dimensions
- 25.5 x 15.0 x 0.4 cm
- Weight
- 50g (0.11 lb)
What’s in the Box
- 1 x Cylinder Head Gasket (Replaces 350-01005-0/350-01005-1)
Installation Notes
- Disconnect the battery and ground the ignition system for safety.
- Drain the engine coolant completely.
- Remove the cylinder head cover and any other components obstructing access to the head bolts.
- Following the service manual, loosen and remove the head bolts in the specified sequence (typically crisscross, from outside in).
- Carefully lift the cylinder head from the engine block. Avoid using pry tools that could damage the mating surfaces.
- Remove the old head gasket.
- Thoroughly clean both the engine block deck and cylinder head surfaces. Ensure they are free of old gasket material, oil, and debris.
- Position the new gasket, making sure it aligns with the dowel pins and bolt holes. Do not use sealants unless specified by the engine manufacturer.
- Carefully place the cylinder head back onto the block.
- Install and tighten the head bolts in the correct sequence and to the specified torque settings using a calibrated torque wrench.
Troubleshooting & FAQ
How do I know if this gasket fits my engine?
Check the "Engine & Model Compatibility" table. It's crucial to match your engine's brand, model, horsepower, and year or serial number range. For Mercury/Mariner models, confirm your serial number is 0N001590 or higher.
What are the signs of a failing head gasket?
Common symptoms include engine overheating, a noticeable loss of power, milky or discolored engine oil (coolant mixing with oil), bubbling in the radiator or coolant reservoir, and white, sweet-smelling smoke from the exhaust.
When should a head gasket be replaced?
Head gaskets are typically replaced only when they fail. They do not have a standard service interval. You can extend the life of your gasket by preventing engine overheating and performing regular cooling system maintenance.
Do I need special tools for this installation?
Yes, a calibrated torque wrench is essential. Tightening the head bolts to the manufacturer's specified torque and in the correct sequence is critical for creating a proper seal and preventing engine damage.
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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