Piston Kit .030 Oversize – Fits Mercury/Mariner 75-125 HP (Replaces 2704-821896A4)
Piston Kit .030 Oversize – Fits Mercury/Mariner 75-125 HP (Replaces 2704-821896A4) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Piston Kit .030 Oversize – Fits Mercury/Mariner 75-125 HP (Replaces...
Product Details
This Piston Kit .030 Oversize – Fits Mercury/Mariner 75-125 HP (Replaces 2704-821896A4) is engineered for Mercury and Mariner 75-125 HP, 3 & 4-cylinder loop-charged outboard engines manufactured between 1994 and 2006. It serves as a high-quality replacement for worn or damaged pistons, restoring compression and engine performance.
It provides a direct interchange for several part numbers, including GLM 14490, Sierra 18-4628, Mallory 9-53252, ProV 6230V, and Asaki 2704-821896A4.
- Designed for .030" oversize (3.530" bore) applications.
- Constructed from durable aluminum alloy for longevity.
- Includes piston, pin, clips, and rings for a complete installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| GLM | 14490 |
| Sierra | 18-4628 |
| Mallory | 9-53252 |
| ProV | 6230V |
| Asaki | 2704-821896A4 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury models, this kit fits various 75, 90, 100, 115, and 125 HP loop-charged outboards from the mid-1990s through the mid-2000s, including specific later models.
For Mariner models, compatibility covers 75, 90, 100, 115, and 125 HP loop-charged outboards across similar year ranges.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | Outboard | 75 | Loop-charged | 1994, 1996, 1999, 2001, 2003, 2005 | 2704-821896A4 | 3-cylinder |
| Mercury | Outboard | 75 | Loop-charged | 2014 | 2704-821896A4 | Model 1075412EY |
| Mercury | Outboard | 90 | Loop-charged | 1995–1996, 2000, 2002–2003, 2005 | 2704-821896A4 | 3-cylinder |
| Mercury | Outboard | 90 | Loop-charged | 2010 | 2704-821896A4 | Models 1090412FF/1090422FF/1090472FF |
| Mercury | Outboard | 90 | Loop-charged | 2014 | 2704-821896A4 | Models 1090412HF/1090422HF |
| Mercury | Outboard | 100 | Loop-charged | 1994–1995 | 2704-821896A4 | Models 1100412PD/1100412RB, 4-cylinder |
| Mercury | Outboard | 115 | Loop-charged | 1996 | 2704-821896A4 | Models 1115412SN/1115472SD, 4-cylinder |
| Mercury | Outboard | 115 | Loop-charged | 2000–2006 | 2704-821896A4 | 4-cylinder |
| Mercury | Outboard | 125 | Loop-charged | 1996 | 2704-821896A4 | Model 1125412SN, 4-cylinder |
| Mercury | Outboard | 125 | Loop-charged | 2000–2005 | 2704-821896A4 | Model 1125412WB, 4-cylinder |
| Mariner | Outboard | 75 | Loop-charged | 1994–1998, 2000–2005 | 2704-821896A4 | 3-cylinder |
| Mariner | Outboard | 90 | Loop-charged | 1994–1998, 2000–2005 | 2704-821896A4 | 3-cylinder |
| Mariner | Outboard | 100 | Loop-charged | 1998, 2000 | 2704-821896A4 | Models 7100421GD/7100412JB, 4-cylinder |
| Mariner | Outboard | 115 | Loop-charged | 1995–1998, 2000–2006 | 2704-821896A4 | 4-cylinder |
| Mariner | Outboard | 125 | Loop-charged | 1995–1998, 2000–2004 | 2704-821896A4 | 4-cylinder |
Technical Specs
- Product Type
- Piston Kit, .030 Oversize
- Bore Size
- 3.530" (89.66 mm)
- Standard Bore
- 3.500" (88.9 mm)
- Oversize
- .030" (0.762 mm)
- Material
- Aluminum Alloy
- Application
- Loop-charged 3 & 4-cylinder outboards
- Product Height
- 3.75 in
- Product Width
- 3.67 in
- Product Length
- 3.67 in
What’s in the Box
- 1 x Piston
- 1 x Piston Pin
- 2 x Circlips/Retaining Clips
- 2 x Piston Rings
Installation Notes
- Ensure the engine is cool and disconnect the battery. Drain the engine oil and coolant.
- Remove the cylinder head and any other components blocking access to the piston.
- Carefully push the old piston out from the bottom of the cylinder.
- Inspect the cylinder for scoring or damage. Hone the cylinder to the correct size for the new oversized piston.
- Clean the cylinder bore thoroughly to remove any metal debris.
- Lubricate the new piston and rings with fresh engine oil.
- Use a ring compressor to carefully install the new piston assembly into the cylinder.
- Reinstall the piston pin and retaining clips.
- Reassemble the engine components in reverse order of removal, following torque specifications from your service manual.
- Refill engine oil and coolant. Reconnect the battery and check for leaks before starting.
Troubleshooting & FAQ
How do I know if I need a .030 oversized piston?
An oversized piston is needed when the cylinder has been bored out to correct for wear, tapering, or out-of-round conditions. Measurements of the cylinder bore diameter with a micrometer will determine the required piston size. Always consult a professional machinist or your engine's service manual.
What are common signs of a failed piston?
Symptoms include a noticeable loss of engine power, excessive blue or white smoke from the exhaust (indicating oil burn), low compression in one or more cylinders, and a knocking or rattling sound from the engine.
Is this kit compatible with both 3-cylinder and 4-cylinder engines?
Yes, this piston kit is designed for use in both the 3-cylinder (75/90 HP) and 4-cylinder (100/115/125 HP) loop-charged Mercury and Mariner engines listed in the compatibility table.
Do I need to check the piston ring end gap?
Yes, it is critical to check the end gap of the new piston rings before installation. Place each ring in the cylinder bore and measure the gap with a feeler gauge. The required gap is specified in your engine's service manual.
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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