Bonbo Bearing Carrier Retainer Wrench for Mercruiser Alpha & Bravo One 4-3/8" — Heat-Treated Steel, Black-Oxide Finish

The Bonbo Bearing Carrier Retainer Wrench is a heavy-duty, direct-replacement tool made to remove and install the 4-3/8" retainer nut on Mercruiser Alpha and Bravo One outdrives.

This purpose-built wrench matches OEM fitments for part numbers 91-61069, 91-61069T and 18-9858 and is engineered for repeatable, precise engagement with Mercruiser Alpha One, Pre-Alpha, Generation I and II, and Bravo One (TRS) drive units. Constructed from heat-treated steel with a black-oxide finish, the tool resists corrosion and impact while delivering the torque control technicians need during impeller service, gearbox maintenance and outdrive rebuilds.

Will this wrench work with my Mercruiser outdrive?

Yes — the wrench is sized specifically for the 4-3/8" bearing carrier retainer nut used on many Alpha family outdrives. It does not fit Bravo Two, Bravo Three, XR or TR models, so verify your outdrive type before ordering.

• Compatible with Mercruiser Alpha One, Pre-Alpha, Generation I and II, Bravo One TRS
• Fits Mercury/Mariner outboards 150 HP and larger
• Replaces OEM 91-61069, 91-61069T, 18-9858
• Not compatible with Bravo 2/3, XR or TR models

How durable is the Bonbo retainer wrench under heavy use?

The wrench is forged from high-grade steel and finished with a black-oxide coating to resist rust and wear during repeated shop and field use. Precision machining keeps the engagement surfaces true so the tool won’t slip or round off the retainer nut under normal service torque.

• Heat-treated steel body for strength and wear resistance
• Black-oxide finish to minimize corrosion in marine environments
• Precision-cut engagement for secure, non-slip contact
• Impact-resistant design for mechanic use

How do I use this wrench safely for outdrive service?

Fit the wrench squarely over the 4-3/8" retainer nut, then apply steady torque using an appropriate breaker bar or torque wrench. Avoid sudden impacts unless using an impact-rated drive and follow the manufacturer's torque and disassembly instructions for your specific engine and year.

• Seat wrench fully on retainer nut before applying torque
• Use hand tools for controlled torque; reserve impacts for compatible tools
• Follow engine-specific torque specifications and removal order
• Inspect tool and nut faces for damage before reuse

What makes this Bonbo tool different from the OEM version?

Bonbo's tool is manufactured to match OEM dimensions while offering a robust black-oxide finish and quality steel at a better value. It's produced as a direct-fit replacement to simplify maintenance without changing service procedures or specialized equipment.

• Direct-fit replacement for OEM part numbers
• Cost-effective option with OEM-equivalent dimensions
• Finished to resist saltwater and workshop conditions
• Backed by Bonbo's customer satisfaction policy

Who is this for? The Bonbo Bearing Carrier Retainer Wrench is aimed at marine technicians, DIY boat owners and service shops that maintain Mercruiser Alpha-series outdrives. If you perform impeller, bearing or gearcase work on Alpha One, Generation I/II or Bravo One TRS drives and need a dependable, OEM-fit tool without a premium price, this wrench is designed for your toolbox.