Hinge Pin Tool – Fits Mercury/MerCruiser Sterndrive Alpha One Gen 1 & 2, Bravo I, II & III (Replaces 91-78310)
Hinge Pin Tool – Fits Mercury/MerCruiser Sterndrive Alpha One Gen 1 & 2, Bravo I, II & III (Replaces 91-78310) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Hinge Pin Tool – Fits Mercury/MerCruiser Sterndrive Alpha One Gen 1...
Hinge Pin Tool – Fits Mercury/MerCruiser Sterndrive Alpha One Gen 1 & 2, Bravo I, II & III (Replaces 91-78310) is backordered and will ship as soon as it is back in stock.
Product Details
This specialized hinge pin tool is designed to remove and install hinge pins on Mercury/MerCruiser sterndrive units. It is listed for Mercury/MerCruiser Alpha One Gen 1 and Gen 2 and Bravo I, II and III applications, subject to confirmation against the specific drive and service manual.
The tool replaces Mercury Marine OEM part number 91-78310. Catalog references identify it as a service tool for removing and installing hinge pins during sterndrive service.
- Product Type: Hinge pin service tool
- Operation: Manual use with a suitable drive tool or wrench
- Primary Function: Removes and installs hinge pins
- Application: Mercury/MerCruiser sterndrive service
Part Number Matrix
These are manufacturer or aftermarket catalog references associated with the hinge pin tool. Confirm the part description and application before ordering.
| Brand | Part Number | Reference Type |
|---|---|---|
| Mercury Marine | 91-78310 | OEM replacement reference |
| Sierra | 18-9861 | Aftermarket catalog reference |
| GLM | 90200 | Aftermarket catalog reference |
Engine & Model Compatibility
This tool is intended for Mercury/MerCruiser sterndrives that use the corresponding hinge pin service arrangement. Model and serial-number coverage can vary, so compare your drive with the service manual and the original tool or hinge pin before purchase.
| Brand | Model | Application | Year / Serial Condition | OEM Reference | Service Function |
|---|---|---|---|---|---|
| MerCruiser | Alpha One Gen 1 | Sterndrive | Not specified; verify by drive and serial number | 91-78310 | Removes and installs hinge pins |
| MerCruiser | Alpha One Gen 2 | Sterndrive | Not specified; verify by drive and serial number | 91-78310 | Removes and installs hinge pins |
| MerCruiser | Bravo I | Sterndrive | Not specified; verify by drive and serial number | 91-78310 | Removes and installs hinge pins |
| MerCruiser | Bravo II | Sterndrive | Not specified; verify by drive and serial number | 91-78310 | Removes and installs hinge pins |
| MerCruiser | Bravo III | Sterndrive | Not specified; verify by drive and serial number | 91-78310 | Removes and installs hinge pins |
Technical Specs
- Product Type
- Service tool — hinge pin tool
- Function
- Removal and installation of Mercury/MerCruiser sterndrive hinge pins
- Operation
- Manual
- OEM Replacement Reference
- Mercury Marine 91-78310
- Application
- Mercury/MerCruiser sterndrive units, including listed Alpha One and Bravo applications
- Year / Serial Coverage
- Not specified; verify with the applicable service information
What’s in the Box
- 1 x Hinge pin tool
Installation Notes
- Secure the boat and sterndrive unit according to the applicable service procedure before beginning work.
- Locate the hinge pins connecting the sterndrive assembly to the bell housing or gimbal-ring assembly.
- Position the tool squarely on the hinge pin and ensure it is fully seated before applying force.
- Use the appropriate wrench or drive tool to remove or install the hinge pin. Do not force a misaligned tool.
- Follow the official Mercury/MerCruiser service manual for the correct sequence, inspection requirements and torque specifications.
Troubleshooting & FAQ
What drives is this tool intended for?
The listed applications include Mercury/MerCruiser Alpha One Gen 1, Alpha One Gen 2, Bravo I, Bravo II and Bravo III sterndrives. Exact coverage may depend on the drive version and serial number, so verify the service-manual application before ordering.
What does this tool do?
It is used to remove and install hinge pins during Mercury/MerCruiser sterndrive service.
How should the tool be used?
Seat the tool squarely on the hinge pin, then use a suitable wrench or drive tool while following the applicable service procedure. Keep the tool aligned to reduce the risk of slipping or damaging the pin.
What if the tool slips?
Stop work and inspect the tool and hinge pin for incorrect fit, wear, corrosion or damage. Clean the contact surfaces, confirm the application and make sure the tool is fully seated before trying again.
Is this a replacement for Mercury Marine part number 91-78310?
Yes. Catalog references identify this hinge pin tool as a replacement for Mercury Marine OEM part number 91-78310.
Is this an OEM Mercury Marine tool?
This listing is for an aftermarket replacement tool. Mercury Marine part number 91-78310 is shown as the OEM replacement reference, not as the brand of the item supplied in this listing.
Can it be used for other applications?
Use it only for compatible hinge pin service applications. Do not use it as a general-purpose socket or apply it to unrelated fasteners.
Safety & Important Info
- Verify the drive model, version and serial-number requirements before ordering.
- Compare the tool with the original hinge pin and applicable service information if fitment is uncertain.
- Use appropriate eye protection and follow safe sterndrive-support procedures during service.
- Follow the official service manual for disassembly, installation and torque requirements.
- This is an aftermarket replacement tool, not an OEM Mercury Marine component.
About Sea Sierra
- Marine Service Products — Practical replacement parts and service tools for marine maintenance.
- Application-Focused Listings — Product information is organized around common marine service applications and reference numbers.
- Support for Fitment Checks — Compare model, drive version and service-manual information before ordering.
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