Hinge Pin Tool – Fits Mercury MerCruiser Alpha One & Bravo Drives (Replaces 91-78310)

Hinge Pin Tool – Fits Mercury MerCruiser Alpha One & Bravo Drives (Replaces 91-78310)

This specialized service tool is designed for the removal and installation of hinge pins on Mercury MerCruiser sterndrive bell housings. It is compatible with Alpha One (Gen I & II), Bravo One, Two, Three, and XR series sterndrive models from 1984 to the current production year.

This tool is a direct replacement for Mercury part number 91-78310, Sierra 18-9861, and VG Marine 90200.

• Material: Fabricated from hardened steel with a black oxide coating for superior rust protection.
• Application: Used for servicing bellows, gimbal bearings, shift cables, and trim senders by accessing the hinge pins connecting the bell housing to the gimbal ring.
• Design: Features a 1/2-inch, 12-point, or hex drive interface for secure engagement.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

• 1 x PIN TOOL Hinge (91-78310)

Installation Guide

1. To gain access, begin by removing the trim and tilt sender from the sterndrive assembly.
2. Engage the hinge pin tool with the hinge pin on either the port or starboard side of the bell housing.
3. Carefully turn the tool to remove the pin. Note: For stubborn pins, applying heat can prevent damage to the pin or tool.
4. With the pin removed, proceed with service on the bellows, gimbal bearing, shift cables, or other components.
5. After servicing, use the tool to reinstall the hinge pin, securing the bell housing to the gimbal ring.
6. Complete the process by reinstalling the trim and tilt sender unit.

Troubleshooting & FAQ

What is this tool used for?
This is a special service tool for removing and installing the hinge pins on MerCruiser sterndrive units. These pins connect the bell housing to the gimbal ring, and a technician must remove them to service components like bellows, gimbals, and shift cables.

Can I use a different tool instead of this one?
Some mechanics report using a 1/2-inch hex bit socket as an alternative. However, this genuine-specification tool is designed to fit perfectly, reducing the risk of damaging the hinge pin or housing during service.

What should I do if the hinge pin is stuck?
If a hinge pin is difficult to remove, we recommend applying gentle heat to the surrounding housing. This helps expand the metal and loosens the pin, allowing for easier removal and preventing damage.

OEM vs. Aftermarket?
This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

How fast do you ship and how much does it cost?
We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

What is your warranty and return policy?
This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.