Starboard Piston Kit – Fits Mercury/Mariner 135-175 HP 2.0L (Replaces 765-7441T36)

$112.81 $180.00

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Product Details

This aftermarket Starboard Piston Kit – Fits Mercury/Mariner 135-175 HP 2.0L (Replaces 765-7441T36) is engineered for Mercury/Mariner 6-cylinder outboard engines with a 3.125" bore (2.0L, 135-175 HP) from model years 1976–1991.

It serves as a direct cross-reference for multiple OEM and aftermarket part numbers, including Mercury 765-7441T36, Sierra S18-4545, and WSM 100-50SK.

Installation Method: Bottom Guided
Bore Size: 3.125" (Standard, no overbore)
Required Hardware: Use with connecting rod #636

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.

Brand	Part Number
Mercury	765-7441T36
Mercury	765-7441A36
Mercury	765-7441A3
Mercury	765-7449A3
Mercury	765-7228A3
Mercury	765-7056A3
Mercury	765-6521A3
Mercury	765-6310A3
Mercury	765-7441A9
Sierra	S18-4545
WSM	100-50SK

Engine & Model Compatibility

Confirm your engine model and year in the table below.

This piston kit is designed for specific bottom-guided Mercury and Mariner V6 engines.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury	6 Cyl 3.125 Bore 2L	135	2-Stroke	1981–1991	765-7441T36	Bottom guided
Mercury	6 Cyl 3.125 Bore 2L	150	2-Stroke	1979–1991	765-7441T36	Bottom guided
Mercury	6 Cyl 3.125 Bore 2L	175	2-Stroke	1976–1981	765-7441T36	Bottom guided
Mercury	6 Cyl 3.125 Bore 2L XR2	150	2-Stroke	1986–1988	765-7441T36	Bottom guided
Mariner	ALL (compatible models)	135-175	2-Stroke		765-7441T36	Bottom guided

Technical Specs

Product Type: Starboard Piston Kit
Installation: Bottom Guided
Fuel Type: Gasoline
Dimensions: 3.125" (79.375 mm) Bore
Box Dimensions: 15.5" H x 9.5" W x 8.5" L
Fitting Type: Used with connecting rod #636
Other Technical Attributes: Standard size (no overbore)
Warranty: Manufacturer warranty applies

What’s in the Box

1 x Piston
1 x Set of Piston Rings
1 x Wrist Pin
1 x Set of Clips

Installation Notes

Disconnect the battery and relieve any fuel system pressure before servicing.
Drain engine coolant and oil completely.
Remove the cylinder head and any other components blocking access to the piston.
Carefully rotate the crankshaft to bring the target piston to an accessible position (e.g., bottom dead center).
Remove the old connecting rod cap, pin, and piston assembly.
Assemble the new piston, rings, pin, and clips, ensuring correct ring orientation and gap alignment per your engine's service manual.
Thoroughly lubricate the new piston, rings, and cylinder wall with fresh engine oil.
Use a piston ring compressor to carefully guide the new piston assembly into the cylinder.
Re-install the connecting rod cap and torque bolts to manufacturer specifications.
Reassemble all components in reverse order of removal.
Refill with fresh engine oil and coolant. Double-check levels before starting.

Troubleshooting & FAQ

How do I know if this piston fits my engine?

This kit is for specific Mercury/Mariner 6-cylinder 2.0L engines (135–175 HP) from 1976–1991. Confirm your model in the compatibility table and cross-reference your original part number in the matrix. It is a standard 3.125" bore, bottom-guided piston.

What does "bottom guided" installation mean?

"Bottom guided" means the connecting rod's alignment is controlled at the crankshaft journal. This piston is specifically designed for engines using this system (with connecting rod #636). Installing it in a top-guided engine will cause catastrophic failure.

Is this a standard or oversized piston?

This is a standard size piston for a 3.125-inch bore. It is not an overbore piston and should only be used in cylinders that meet standard factory specifications.

What are common signs of a failed piston?

Symptoms of a failing piston include significant loss of compression in a cylinder, excessive oil consumption, blue-tinted smoke from the exhaust, audible knocking or slapping sounds from the engine block, and a general lack of power.

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

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