Piston Kit .030 Oversize – Fits Mercury/Mariner 45-60 HP (Replaces 783-9613T3)
Piston Kit .030 Oversize – Fits Mercury/Mariner 45-60 HP (Replaces 783-9613T3) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Free standard shipping on all orders under 1 KG
Piston Kit .030 Oversize – Fits Mercury/Mariner 45-60 HP (Replaces ...
Product Details
This Piston Kit .030 Oversize – Fits Mercury/Mariner 45-60 HP (Replaces 783-9613T3) is engineered for 3-cylinder 45-60 HP 2-Stroke Mercury and Mariner outboard engines manufactured between 1991 and 2002. It provides a complete solution for engine rebuilds where the cylinder has been machined .030" over standard bore.
It serves as a direct interchange for Mercury OEM parts 783-9613T3 and 783-9613A3, along with aftermarket cross-references including Sierra 18-4018, GLM 14090, and Mallory 9-53210.
- Designed for loopcharged 3-cylinder engine models.
- Engineered from a durable cast aluminum alloy for reliable performance.
- Kit includes all essential components: piston, rings, wrist pin, and circlips.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 783-9613T3 |
| Mercury | 783-9613A3 |
| Sierra | 18-4018 |
| GLM | 14090 |
| Mallory | 9-53210 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury/Mariner engines, verify your engine's horsepower rating and year range fall within the compatibility list.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury/Mariner | 3-cylinder | 45 Jet | 2-Stroke | 1991–1997 | 783-9613T3 | Loopcharged |
| Mercury/Mariner | 3-cylinder | 50 | 2-Stroke | 1991–2002 | 783-9613T3 | Loopcharged |
| Mercury/Mariner | 3-cylinder | 55 | 2-Stroke | 1998–2002 | 783-9613T3 | Loopcharged |
| Mercury/Mariner | 3-cylinder | 60 | 2-Stroke | 1991–2002 | 783-9613T3 | Loopcharged |
Technical Specs
- Product Type
- Piston Kit, .030" Oversize
- Material
- Cast Aluminum Alloy
- Piston Diameter
- 75.80 mm (2.985")
- Piston Height
- 69 mm
- Wrist Pin Diameter
- 19.50 mm
- Oversize Amount
- 0.030" over standard bore
- Standard Bore Size
- 75 mm (2.955")
- Weight
- 0.88 kg (1.93 lb)
- Package Contents
- Complete kit with piston, rings, wrist pin and circlips
What’s in the Box
- 1 x Piston Assembly .030 Oversize (783-9613T3)
- 1 x Piston Ring Set .030 Oversize
- 1 x Wrist Pin
- 2 x Circlips
Installation Notes
- Disconnect the battery and secure the engine.
- Remove the powerhead cover and spark plugs.
- Detach the cylinder head, taking care not to damage the gasket surface.
- Carefully extract the old piston assembly from the cylinder.
- Thoroughly inspect the cylinder bore for scoring or wear. The cylinder must be bored and honed to accommodate the .030" oversize piston.
- Lubricate the new piston, rings, and wrist pin with 2-stroke engine oil before assembly.
- Install one wrist pin circlip into the piston.
- Slide the wrist pin through the piston and connecting rod, then secure it with the second circlip.
- Using a ring compressor, gently guide the piston assembly into the cylinder with the arrow on the piston crown facing the exhaust side.
- Reinstall the cylinder head with a new gasket, torquing bolts to the manufacturer's specified sequence and values.
- Complete reassembly of all components and verify all connections are secure.
Troubleshooting & FAQ
How do I confirm this is the correct piston for my engine?
Verify your engine is a Mercury or Mariner 3-cylinder model from 45-60 HP, built between 1991–2002. Most importantly, measure your cylinder bore. This piston is for a bore that has been machined to .030" (0.76 mm) over the standard 75 mm size.
What are the signs that I need to replace my pistons?
Common symptoms of piston failure include low compression in one or more cylinders, excessive exhaust smoke, loss of engine power, or audible knocking and rattling sounds from the powerhead.
Is honing the cylinder necessary before installing this kit?
Yes. After boring the cylinder to the correct oversize, it must be honed to create the proper cross-hatch pattern on the cylinder wall. This ensures the new piston rings will seat correctly, providing optimal compression and heat transfer.
What is the difference between a standard and an oversized piston?
A standard piston fits the original, factory-specified cylinder bore. An oversized piston is used after an engine cylinder has been worn or damaged and then machined (bored out) to a larger, clean diameter. This .030" oversize kit is for cylinders that have been bored 0.030 inches larger than standard.
Are gaskets included with this kit?
No, this kit contains only the piston, rings, wrist pin, and circlips. Gaskets for the cylinder head and other components must be purchased separately.
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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