Hinge Pin Tool – Fits Mercury/MerCruiser Alpha 1 Gen 1 & 2, Bravo I II III (Replaces 91-78310)
Hinge Pin Tool – Fits Mercury/MerCruiser Alpha 1 Gen 1 & 2, Bravo I II III (Replaces 91-78310) is backordered and will ship as soon as it is back in stock.
Couldn't load pickup availability
Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Hinge Pin Tool – Fits Mercury/MerCruiser Alpha 1 Gen 1 & 2, Bra...
Product Details
This specialized Hinge Pin Tool – Fits Mercury/MerCruiser Sterndrive Alpha 1 Gen 1 & 2, Bravo I II III (Replaces 91-78310) is engineered for removing and installing hinge pins from the bell housing on most Mercury MerCruiser sterndrive units. It is a crucial service tool for working on Alpha One (Gen 1 and 2), Bravo (I, II, III, X, XR, XZ), MC-1, and MR drives.
It serves as a direct replacement for Mercury/MerCruiser 91-78310, Sierra 18-9861, GLM 90200, and Mallory 9-79805.
- Installation Method: Manual; requires a standard socket wrench.
- Material: Constructed from durable, machined steel for strength and longevity.
- Design: Features a 12-point head for a secure grip and easy operation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/MerCruiser | 91-78310 |
| Sierra | 18-9861 |
| GLM | 90200 |
| Mallory | 9-79805 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This tool is designed for use on a wide range of MerCruiser sterndrives that use hinge pins for the bell housing.
| Brand | Model | Application | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|
| MerCruiser | Alpha One Gen 1 | Sterndrive | All | 91-78310 | Used to remove/install hinge pins |
| MerCruiser | Alpha One Gen 2 | Sterndrive | All | 91-78310 | Used to remove/install hinge pins |
| MerCruiser | Bravo I | Sterndrive | All | 91-78310 | Used to remove/install hinge pins |
| MerCruiser | Bravo II | Sterndrive | All | 91-78310 | Used to remove/install hinge pins |
| MerCruiser | Bravo III | Sterndrive | All | 91-78310 | Used to remove/install hinge pins |
| MerCruiser | Bravo X | Sterndrive | All | 91-78310 | Used to remove/install hinge pins |
| MerCruiser | Bravo XR | Sterndrive | All | 91-78310 | Used to remove/install hinge pins |
| MerCruiser | Bravo XZ | Sterndrive | All | 91-78310 | Used to remove/install hinge pins |
| MerCruiser | MC-1 | Sterndrive | All | 91-78310 | Used to remove/install hinge pins |
| MerCruiser | MR | Sterndrive | All | 91-78310 | Used to remove/install hinge pins |
Technical Specs
- Product Type
- Service Tool (Hinge Pin Tool)
- Installation
- Manual
- Material
- Machined Steel
- Color
- Silver
- Thread Size
- Matches MerCruiser sterndrive hinge pin threading
- Warranty
- 1 Year
- Other Technical Attributes
- 12-point design for use with standard socket wrench
What’s in the Box
- 1 x Hinge Pin Tool (91-78310)
Installation Notes
- Safely secure the sterndrive unit to prevent movement during service. Locate the hinge pins connecting the bell housing to the gimbal ring.
- Position the hinge pin tool squarely onto the head of the hinge pin. Ensure it is fully seated for a secure grip.
- Attach a properly sized socket wrench to the 12-point head of the tool.
- To remove, apply steady counter-clockwise pressure. To install, thread the pin by hand first, then use the tool to tighten clockwise to the manufacturer's specified torque.
- Always refer to your official service manual for detailed procedures and torque specifications.
Troubleshooting & FAQ
What drives is this tool compatible with?
This tool is designed for a wide range of Mercury/MerCruiser sterndrives, including Alpha One (Gen 1 & 2), Bravo (I, II, III, X, XR, XZ), MC-1, and MR models. It is specifically made to fit the hinge pins on these units.
How do I use this tool?
The tool fits over the hinge pin head. Attach a standard socket wrench to the tool's 12-point end to loosen (counter-clockwise) or tighten (clockwise) the hinge pins during installation or removal.
What if the tool slips on the hinge pin?
Ensure the tool is fully seated on the hinge pin and that the pin head is not excessively worn or corroded. The 12-point design provides a strong grip on undamaged pins. Using the correct size socket wrench is also critical.
Is this a replacement for OEM part number 91-78310?
Yes, this is a direct aftermarket replacement for Mercury/MerCruiser part number 91-78310, as well as several other aftermarket cross-references.
Can this be used for applications other than hinge pins?
This tool is specifically designed with the correct threading and size for MerCruiser hinge pins. Using it for other purposes is not recommended and may cause damage.
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
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
