Bellow Retainer Ring Installation Tool – Fits Mercury MerCruiser Bravo 1, 2, 3 and Alpha One Gen 2 (Replaces 818162, 43577)

$12.99

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Product Details

This specialized Bellow Retainer Ring Installation Tool is engineered for installing the aluminum retainer ring into the U-joint bellows on a wide range of Mercury MerCruiser sterndrives. It is specifically designed for MerCruiser Bravo One, Two, Three, Bravo X/XR/XZ series, and Alpha One Generation II sterndrives manufactured from 1988 to the present.

This tool serves as a direct replacement for Mercury part numbers 91-818162 and 43577, as well as Sierra 18-9870 and Mallory 9-79821.

Used to install the aluminum retainer ring into U-joint bellows.
Constructed from high-grade steel for durability and precise fit.
Requires a compatible driver rod for optimal performance.

Part Number Matrix

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

Brand	Part Number
Mercury	91-818162 / 818162
Mercury	43577
Sierra	18-9870
Mallory	9-79821

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury/MerCruiser models, this tool fits Alpha One Gen II (1992–present) and various Bravo series drives (1988–present). Please verify your specific model and serial number range for an exact match.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury	Alpha One Gen II	120–300	4-Stroke	1992–Present	91-818162	Primary application
Mercury	Bravo One	250–500+	4-Stroke	1988–Present	91-818162	High-performance drives
Mercury	Bravo Two	300–500+	4-Stroke	1988–Present	91-818162	Heavy-duty applications
Mercury	Bravo Three	250–500+	4-Stroke	1988–Present	91-818162	Dual-prop configuration
Mercury	Bravo X ONE, TWO, THREE	250–500+	4-Stroke	1998–2013	91-818162	Later series [0M100001-0W249999]
Mercury	Bravo XZ ONE	250–500+	4-Stroke	1998–2002	91-818162	Series [0L914990-0M999999]
Mercury	Bravo XR ONE	250–500+	4-Stroke	1998–2002	91-818162	Series [0L914990-0M999999]
Mercury	Bravo XR ONE, THREE	250–500+	4-Stroke	1998–2009	91-818162	Series [0W240000 and up]
Mercury	Bravo XR SPORTMASTER	250–500+	4-Stroke	1998–2002	91-818162	Series [0M052945-0M906877]
Mercury	Bravo XR SPORTMASTER	250–500+	4-Stroke	1998–2009	91-818162	Series [0M906878 and up]
Mercury	INTEGRATED TRANSOM	250–500+	4-Stroke	1998–2002	91-818162	Series [0ALL-0M052767]
Mercury	INTEGRATED TRANSOM	250–500+	4-Stroke	1998–2009	91-818162	Series [0M052768 and up]
Mercury	HI PERFORMANCE TRANSOM	250–500+	4-Stroke	1998–2009	91-818162	Series [0W150003 and up]

Technical Specs

Product Type: Drive Shaft Bellow Retainer Ring Installation Tool
Installation: Used to install aluminum retainer ring into U-joint bellows
Housing Material: High-grade steel
Dimensions: Approximately 89 mm diameter × 25 mm height (3.5" × 1")
Weight: Approximately 150 g (5.3 oz)
Fitting Type: Precision-machined installation sleeve
Operating Temperature: Standard ambient conditions (-10°C to 50°C / 14°F to 122°F)
Other Technical Attributes: Requires driver rod for optimal performance; installs retainer rings for U-joint bellows

What’s in the Box

1 × Bellow Retainer Ring Installation Tool (91-818162, 43577)

Installation Notes

Ensure the sterndrive unit is safely tilted up and accessible.
Place the new U-joint bellows onto the gimbal housing.
Insert the aluminum retainer ring into the designated groove on the new bellows.
Position this installation tool evenly over the retainer ring.
Using a compatible driver rod, carefully apply pressure to drive the tool, seating the ring securely into the bellow's groove.
Once fully seated, visually inspect the ring to confirm it is flush and evenly installed.
Carefully remove the installation tool. The bellows is now secured.

Troubleshooting & FAQ

What sterndrives is this installation tool compatible with?

This tool is designed for Mercury MerCruiser Alpha One Gen II (1992–present), Bravo One, Bravo Two, Bravo Three (1988–present), and Bravo X/XR/XZ series sterndrives. Always check your specific model and year before ordering.

What is this tool made of?

The OEM version and this high-quality aftermarket tool are made from high-grade steel for strength and longevity. Note that some other, lower-quality aftermarket versions may be made of plastic.

Do I need other tools to use this one?

Yes, a compatible driver rod is required to apply even pressure and correctly seat the retainer ring. This tool is the sleeve that guides the ring into place.

How can I tell if the retainer ring is installed correctly?

A properly installed retainer ring will be fully seated and sit flush within the U-joint bellow's groove. Visually inspect it from all angles to ensure it is even and secure before completing the reassembly.

What part numbers does this tool cross-reference with?

This tool is an aftermarket equivalent for Mercury 91-818162 and 43577, Sierra 18-9870, and Mallory 9-79821.

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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Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

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