Sierra 18-5611 Outboard Starter, Replaces 50-90983T1, Fits 6-15 HP (1986-96) & 18-25 HP (1980-87), 10 Tooth Drive Gear

The Sierra 18-5611 is an outboard starter built as a direct replacement for outboard engines in the 6-15 HP (1986-96) and 18-25 HP (1980-87) range, using a 10 tooth drive gear configuration. It is engineered to restore reliable cranking performance on outboards where the original starter has failed or is showing signs of wear, such as slow cranking, clicking without engagement, or complete no-start conditions tied to the starter motor itself.

This starter is rated at 20 amps and 1.4 kW, providing the electrical draw and output needed to turn over the engine consistently in the covered horsepower range. It is finished in white to match OEM outboard cowling and powerhead components. As a Sierra product, it is built to meet or exceed the performance of the original equipment part it replaces, giving boat owners and marine technicians a dependable option for engine maintenance and repair.

The 18-5611 is compatible with multiple OEM part numbers, so it can be used as a cross-reference replacement without needing to track down a specific original manufacturer part. It is sized to install using the same mounting configuration as the original starter on the covered engines, with the 10 tooth drive gear matching the flywheel engagement of these outboard applications.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-5611
• Product Type: Outboard Starter
• Color: White
• Amperage: 20 Amps
• Wattage: 1.4 kW
• Drive Gear: 10 tooth
• Fitment (Horsepower): 6-15 HP (1986-96); 18-25 HP (1980-87)
• Item Dimensions: 9 x 4.75 x 4.75 inches
• Weight: 3.69 pounds
• UPC: 747730043982
• OEM Cross Reference: 50-90983A-1, 50-90983T1, 50-8M0033984

Fitment

• 6-15 HP outboards (1986-96), 10 tooth drive gear
• 18-25 HP outboards (1980-87), 10 tooth drive gear

Replaces (OEM)

• 50-90983A-1
• 50-90983T1
• 50-8M0033984

Frequently Asked Questions

What engines does the Sierra 18-5611 starter fit? The 18-5611 fits outboards rated 6-15 HP from 1986-96 and 18-25 HP from 1980-87, using a 10 tooth drive gear.

What OEM part numbers does the 18-5611 replace? It replaces OEM numbers 50-90983A-1, 50-90983T1, and 50-8M0033984, so it can be ordered as a direct cross-reference without sourcing the original part.

How many teeth are on the drive gear of this starter? The 18-5611 starter uses a 10 tooth drive gear, matching the flywheel engagement on its listed 6-15 HP and 18-25 HP outboard applications.

What color is the Sierra 18-5611 starter? It is finished in white, consistent with the cowling and powerhead color on the outboards it fits.

What are the electrical ratings of the 18-5611 starter? This starter is rated at 20 amps and 1.4 kW of output, sized to reliably crank engines in the 6-15 HP and 18-25 HP range it is built for.

How much does the 18-5611 starter weigh? The Sierra 18-5611 outboard starter weighs 3.69 pounds.

What are the physical dimensions of the 18-5611? The unit measures 9 x 4.75 x 4.75 inches, sized for direct installation in place of the original starter on covered outboards.

Is the Sierra 18-5611 a genuine OEM part or aftermarket replacement? It is a Sierra aftermarket replacement starter, built to meet or exceed the performance of the original equipment starter it replaces on 6-15 HP (1986-96) and 18-25 HP (1980-87) outboards.

Will the 18-5611 fit an outboard outside the 6-15 HP or 18-25 HP range? No, the 18-5611 is built specifically for 6-15 HP (1986-96) and 18-25 HP (1980-87) outboards with a 10 tooth drive gear; other horsepower ranges require a different starter.

What is included when ordering the 18-5611? Ordering the Sierra 18-5611 gets you one complete outboard starter unit ready to install in place of the original.

Does the 18-5611 include a UPC for retail or inventory tracking? Yes, the Sierra 18-5611 starter is identified by UPC 747730043982.