Sierra 18-1118 Drive Shaft Tapered Roller Bearing for Mercury/Mariner 100 HP (4 Cyl.) Outboards

The Sierra 18-1118 is a tapered roller bearing designed to support the drive shaft in the gearcase of Mercury and Mariner outboard motors. This bearing is built as a direct-fit replacement for the drive shaft position in the lower unit, where it carries radial and thrust loads generated by the drive shaft as it transmits power from the powerhead down to the gearcase. Tapered roller bearings of this type are chosen for drive shaft applications because they handle combined axial and radial loads more effectively than ball bearings, which is important given the constant load reversals a drive shaft experiences during shifting and throttle changes.

The 18-1118 is intended for Mercury/Mariner 100 hp (4 cylinder) outboards with serial number B209468 and up. It is lubricated with marine gearcase grease and is sized to fit the compact dimensions of the outboard's lower unit drive shaft bore. As a wear item inside the gearcase, this bearing is typically replaced during a gearcase rebuild, when a drive shaft is replaced, or when diagnosing gearcase noise or play that points to a worn bearing.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-1118
• Product Type: Drive Shaft Tapered Roller Bearing
• Bearing Type: Tapered Roller Bearing
• Compatible Lubricant: Grease
• Item Dimensions: 0.39 x 0.39 x 0.39 inches
• Weight: 0.69 pounds
• UPC: 030999974259

Fitment

• Mercury/Mariner 100 hp (4 cylinder) outboards, serial number B209468 and up

Frequently Asked Questions

What is the Sierra 18-1118 used for? The Sierra 18-1118 is a tapered roller bearing that supports the drive shaft inside the gearcase of Mercury/Mariner outboard motors, carrying the radial and thrust loads the drive shaft generates during operation.

Which outboards does the 18-1118 fit? This bearing fits Mercury/Mariner 100 hp (4 cylinder) outboards with serial number B209468 and up.

Is the 18-1118 a ball bearing or a roller bearing? It is a tapered roller bearing, which is better suited than a ball bearing to the combined radial and thrust loads a drive shaft puts on the gearcase.

What lubricant should be used with this bearing? The Sierra 18-1118 is designed to run on marine gearcase grease as its compatible lubricant.

What are the dimensions of the 18-1118 bearing? The Sierra 18-1118 measures 0.39 x 0.39 x 0.39 inches.

How much does the 18-1118 weigh? It weighs 0.69 pounds.

How many bearings come in a package? The 18-1118 is sold as a single drive shaft bearing, one unit count per package.

When should this drive shaft bearing be replaced? A drive shaft bearing like the 18-1118 is typically replaced during a gearcase rebuild, when the drive shaft itself is replaced, or when gearcase noise or play indicates a worn bearing.

Is the Sierra 18-1118 an OEM part or an aftermarket replacement? The 18-1118 is a Sierra-branded aftermarket drive shaft bearing made to fit the specified Mercury/Mariner outboard application.

Does the 18-1118 fit outboards below serial number B209468? No, the listed fitment for the 18-1118 is Mercury/Mariner 100 hp (4 cylinder) units with serial number B209468 and up; earlier serial numbers are not covered by this part.

What is the UPC for the Sierra 18-1118? The UPC for the Sierra 18-1118 drive shaft bearing is 030999974259.