Sierra Spanner Nut Wrench 18-9803, Replaces Mercury Marine 91-17256, for MC-I, R-MR, Blackhawk, Bravo and Alpha Drive Units

The Sierra 18-9803 Spanner Nut Wrench is a specialty stern drive tool used to remove and install the driveshaft bearing retainer. It is built for technicians and DIY boat owners servicing MerCruiser MC-I, R-MR, and Blackhawk stern drives, as well as all Bravo and all Alpha drive units, where the bearing retainer must be broken loose and re-torqued correctly during driveshaft bearing service. The wrench features a fixed square head style designed to engage the retainer without slipping or rounding it off, and it carries a powder coated finish in white for corrosion resistance during shop and marina use.

Because the driveshaft bearing retainer sits deep in the gimbal housing area of the drive unit, a purpose-built spanner is required rather than improvised tools, which can damage the retainer or the surrounding housing. The 18-9803 directly replaces Mercury Marine part number 91-17256, so it is a straightforward swap for shops and owners who already reference that OEM number when ordering. As a Sierra product, it is built to meet or exceed the performance of the original equipment part it replaces.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-9803
• Product Name: Spanner Nut Wrench
• Head Style: Fixed Square
• Color: White
• Finish: Powder Coated
• Weight: 1.92 pounds
• Package Dimensions: 4.064 x 39.116 x 14.986 centimeters
• UPC: 808282245078
• Country of Origin: United States
• Category: Mercruiser Specialty Tools

Fitment

• MC-I drive units
• R-MR drive units
• Blackhawk drive units
• All Bravo drive units
• All Alpha drive units

Replaces (OEM)

• Mercury Marine 91-17256

Frequently Asked Questions

What is the Sierra 18-9803 Spanner Nut Wrench used for? It removes and installs the driveshaft bearing retainer on MC-I, R-MR, Blackhawk, all Bravo, and all Alpha stern drive units, making it the correct tool for driveshaft bearing service on those drives.

Does the 18-9803 wrench fit Alpha One drive units? Yes, the Sierra 18-9803 is designed to work on all Alpha drive units, along with MC-I, R-MR, Blackhawk, and all Bravo units.

What OEM part number does the Sierra 18-9803 replace? Mercury Marine 91-17256 is the OEM number that the Sierra 18-9803 Spanner Nut Wrench replaces.

How much does the 18-9803 spanner nut wrench weigh? The Sierra 18-9803 weighs 1.92 pounds.

What color and finish does this wrench have? The 18-9803 has a white, powder coated finish for corrosion resistance in marine service environments.

What head style does the 18-9803 use? A fixed square head style is used on the Sierra 18-9803, which engages the driveshaft bearing retainer without slipping.

Is the Sierra 18-9803 a genuine OEM tool or aftermarket? The 18-9803 is a Sierra aftermarket tool built to meet or exceed the performance of the Mercury Marine 91-17256 retainer wrench it replaces.

Can I use a regular wrench instead of the 18-9803 for retainer removal? The driveshaft bearing retainer on MC-I, R-MR, Blackhawk, Bravo, and Alpha drive units requires a purpose-built spanner like the Sierra 18-9803 to engage it properly without damaging the retainer or housing.

Where is the Sierra 18-9803 manufactured? The Sierra 18-9803 Spanner Nut Wrench is manufactured in the United States.

What is included when I order the 18-9803? The order includes one Sierra 18-9803 Spanner Nut Wrench with a fixed square head, ready to remove or install the driveshaft bearing retainer.

Does the 18-9803 work on Bravo drive units specifically? Yes, the Sierra 18-9803 is compatible with all Bravo drive units in addition to MC-I, R-MR, Blackhawk, and all Alpha units.