Piston Kit – Fits Mercury/Mariner 2-Stroke 3-Cylinder 40-50 HP (Replaces 779-96152)
Piston Kit – Fits Mercury/Mariner 2-Stroke 3-Cylinder 40-50 HP (Replaces 779-96152) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Piston Kit – Fits Mercury/Mariner 2-Stroke 3-Cylinder 40-50 HP (Rep...
Product Details
This aftermarket Piston Kit – Fits Mercury/Mariner 2-Stroke 3-Cylinder 40-50 HP is engineered for a range of Mercury/Mariner 40-50 HP, 2-Stroke, 3-Cylinder engines (1998–2006) and select Tohatsu 40-50 HP, 2-Stroke, 3-Cylinder models (2002–2005).
It provides a direct interchange for Mercury part number 779-96152 and Tohatsu part number 3C8-00004-0 for the standard bore size.
- Manufactured from high-quality cast aluminum alloy for durability and performance.
- Engineered for the standard 68mm (2.992") cylinder bore.
- This complete kit includes the piston, rings, piston pin, and circlips for a full replacement.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Mercury | 779-96152 | Standard Bore Size |
| Tohatsu | 3C8-00004-0 | Standard Bore Size |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury/Mariner engines, this kit fits 3-cylinder powerheads from 1998–2005 that utilize a 2.992" standard bore.
For Tohatsu outboards, this kit is compatible with 3-cylinder M40D2, M50D2, NS40D2, and NS50D2 models from 2002–2005.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 40 HP LIGHTNING/XR/MXL MARATHON | 40 | 2-Stroke | 1998–2005 | 779-96152 | 3-Cylinder, 2.992" STD Bore |
| Mercury | 50 HP | 50 | 2-Stroke | 1998–2005 | 779-96152 | 3-Cylinder, 2.992" STD Bore |
| Mercury | 60 HP | 60 | 2-Stroke | 1998–2005 | 779-96152 | 3-Cylinder powerheads that use 2.992" bore |
| Tohatsu | M40D2 | 40 | 2-Stroke | 2002–2005 | 3C8-00004-0 | 3-Cylinder models |
| Tohatsu | M50D2 | 50 | 2-Stroke | 2002–2005 | 3C8-00004-0 | 3-Cylinder models |
| Tohatsu | NS40D2 | 40 | 2-Stroke | 2002–2005 | 3C8-00004-0 | 3-Cylinder models |
| Tohatsu | NS50D2 | 50 | 2-Stroke | 2002–2005 | 3C8-00004-0 | 3-Cylinder models |
Technical Specs
- Product Type
- Complete Piston Kit
- Material
- Cast Aluminum Alloy
- Bore Size
- 68mm (2.992") Standard
- Stroke
- 2-Stroke
- Cylinder Configuration
- 3-Cylinder
- Product Dimensions
- 8.0" L x 7.5" W x 7.5" H
What’s in the Box
- 1 x Piston
- 1 x Rings set
- 1 x Piston pin
- 2 x Circlips (pin clips)
Installation Notes
- Disconnect the battery and ground the spark plug leads for safety.
- Drain the engine coolant and oil completely.
- Carefully remove the cylinder head and gasket to access the pistons.
- Rotate the crankshaft to bring the piston to a workable position and remove the old piston pin and piston assembly.
- Inspect the cylinder wall for wear, scoring, or damage. Hone the cylinder as needed to ensure a proper surface for the new rings.
- Thoroughly lubricate the new piston, rings, and cylinder wall with fresh 2-stroke engine oil before installation.
- Install the new piston and rings, ensuring ring gaps are correctly oriented according to your engine's service manual.
- Reassemble all components with new gaskets, torquing all bolts to the manufacturer's precise specifications.
- After reassembly, refill all fluids, reconnect the battery, and carefully check for any leaks before starting the engine.
Troubleshooting & FAQ
How do I confirm this kit fits my engine?
Check your engine's model, horsepower, and year against the compatibility table. The most reliable method is to cross-reference the OEM part number (779-96152 for Mercury/Mariner or 3C8-00004-0 for Tohatsu) from your existing piston or service manual.
What are common signs of a worn-out piston?
Symptoms include loss of compression, excessive smoke from the exhaust, a rattling or knocking sound from the engine (piston slap), and reduced overall performance or power.
Is honing the cylinder necessary before installing a new piston?
Yes, it is highly recommended to hone the cylinder walls. This process creates a specific cross-hatch pattern that helps the new piston rings seat correctly, which is essential for achieving optimal compression and engine performance.
Should I replace all pistons in my 3-cylinder engine at the same time?
For balanced performance, even compression, and long-term engine health, it is best practice to replace all pistons and rings simultaneously, especially if the engine has high hours or if one piston has already failed.
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.
Payment & Security
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