Connecting Rod Bearing Kit – Fits Mercury/Mariner 70-300HP (Replaces 31-43012A1)

$54.99 $87.00

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Product Details

This Connecting Rod Bearing Kit is an essential component for rebuilding or repairing Mercury and Mariner outboard engines. It is designed to fit a wide range of 70-300HP 3-cylinder, 4-cylinder, and V6 models manufactured between 1987 and 1998. The caged design ensures proper needle bearing alignment for the big end of the connecting rod, critical for engine reliability and performance.

This kit serves as a direct replacement for Mercury/Mariner part numbers 31-43012A1 and 31-844338A01, and provides an interchange for aftermarket equivalents including GLM 16420, Sierra 18-1195, and TSM BCR-012M7.

Features a durable metal cage housing 16 precision needle bearings.
Installs on the crankshaft journal at the big end of the connecting rod.
Engineered to match OEM specifications for fit, tolerance, and material quality.

Part Number Matrix

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

Brand	Part Number	Superseded By
Mercury/Mariner	31-43012A1	31-844338A01
GLM	16420
Sierra	18-1195
TSM	BCR-012M7

Engine & Model Compatibility

Confirm your engine model/year in the table below.

This bearing kit fits a wide variety of Mercury and Mariner 2-stroke outboards from the late 1980s through the late 1990s.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury/Mariner	3-Cylinder	70	2-Stroke	1987	31-43012A1	Rod No. 638-818846, 938-8532-1
Mercury/Mariner	3-Cylinder	75	2-Stroke	1990–1998	31-43012A1	Serial Range: BEL 9589039 & Up, USA 0C222000 & Up
Mercury/Mariner	3-Cylinder	80	2-Stroke	1987	31-43012A1	Serial Range: BEL 9483121-9589038, USA 0A996142-0C221999
Mercury/Mariner	3-Cylinder	80 Jet	2-Stroke	1994–1998	31-43012A1	Serial Range: BEL 9793577 & Up, USA 0D283222 & Up
Mercury/Mariner	3-Cylinder	90	2-Stroke	1987–1998	31-43012A1	Serial Range: BEL 9483121 & Up, USA 0A996142 & Up
Mercury/Mariner	4-Cylinder	115	2-Stroke	1988–1998	31-43012A1	Serial Range: BEL 9559771 & Up, USA 0C100000 & Up
Mercury/Mariner	4-Cylinder	125	2-Stroke	1994–1998	31-43012A1	Serial Range: BEL 9793577 & Up, USA 0D283222 & Up
Mercury/Mariner	4-Cylinder	65 Jet	2-Stroke	1994–1998	31-43012A1	Serial Range: BEL 9793577 & Up, USA 0D283222 & Up
Mercury/Mariner	V-200 DFI	200	2-Stroke	1997–1998	31-43012A1	Serial Range: USA 0G386496 & Up
Mercury/Mariner	V-225	225	2-Stroke	1995–1998	31-43012A1	Serial Range: USA 0G129222 & Up
Mercury/Mariner	V-225 (Sea Pro)	225	2-Stroke	1994–1998	31-43012A1	Serial Range: USA 0D280813 & Up
Mercury/Mariner	V-225 DFI	225	2-Stroke	1998	31-43012A1	Serial Range: USA 0G590000 & Up
Mercury/Mariner	V-250	250	2-Stroke	1995–1998	31-43012A1	Serial Range: USA 0C101891 & Up
Mercury/Mariner	V-250 EFI	250	2-Stroke	1995–1998	31-43012A1	Serial Range: USA 0G129222 & Up
Mercury/Mariner	V-275	275	2-Stroke	1989–1994	31-43012A1	Serial Range: USA 0C101891 & Up
Mercury/Mariner	V-3.4L	300	2-Stroke	1980–1987	31-43012A1	Serial Range: USA 5611648 & Up

Technical Specs

Product Type: Connecting Rod Bearing Kit (Caged)
Application: Engine Crankshaft (Big End of Connecting Rod)
Housing Material: Metal Cage with Needle Bearings
Needle Quantity: 16
Crankshaft Journal Size: 35.72 mm (1.4063 in)
Package Dimensions: 1.0 in L x 5.13 in W x 4.0 in H

What’s in the Box

16 x Needle Bearings
1 x Metal Cage Assembly

Installation Notes

Thoroughly clean the connecting rod and crankshaft journal, removing all oil and debris.
Inspect the connecting rod and crankshaft for any scoring, burrs, or out-of-round conditions. Address any issues before proceeding.
Apply a liberal amount of 2-stroke engine oil or assembly lube to the new needle bearings, cage, and journal surface.
Carefully place the needle bearings into the cage assembly.
Position the assembled bearing cage onto the crankshaft journal.
Gently guide the big end of the connecting rod over the bearing assembly, ensuring it seats smoothly without dislodging any needles.
Confirm the rod moves freely on the journal with no binding or excessive play.
Always refer to your engine's specific service manual for torque specifications and additional procedures.

Troubleshooting & FAQ

How can I confirm this bearing kit fits my specific engine?

The surest way is to match your engine's model and serial number against the compatibility table. You can also cross-reference your old bearing's part number with our Part Number Matrix. When in doubt, consult your service manual or contact us with your engine details.

What are the signs of a failing connecting rod bearing?

Common symptoms include a distinct knocking or rattling sound from the engine (rod knock), loss of power, increased vibration, and potentially metal shavings found in the lower unit gear oil. Immediate attention is required to prevent catastrophic engine failure.

Is this a bearing for the "big end" or "small end" of the connecting rod?

This is a "big end" bearing kit. It is installed where the connecting rod connects to the engine's crankshaft journal.

What is the main cause of rod bearing failure?

The most common cause is inadequate lubrication from low oil levels, incorrect oil/fuel mixture, or oil delivery issues. Other causes include engine overheating, contamination from dirt or metal particles, and normal wear over many hours of operation.

Can I reuse my old connecting rod if the bearing has failed?

It depends on the condition of the rod. If the old bearing has spun or severely scored the inner surface (the "big end bore") of the connecting rod, the rod must be replaced. Installing a new bearing in a damaged rod will lead to premature failure.

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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Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

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