Sierra 18-5911 Heavy-Duty Marine Starter, Replaces 981078, for GM Engines 100-245 HP 1970-1978

The Sierra 18-5911 is a heavy-duty, bottom mount marine starter engineered for GM engines with a straight across bolt pattern. It is built for GM applications rated 100-245 HP from 1970-1978, delivering standard clockwise rotation for reliable engine cranking in marine environments. The starter is manufactured to meet SAE J1171 and ISO 8846 marine ignition-protection standards, so it is safe for use around gasoline engines and fuel vapors.

Inside, the 18-5911 uses high quality magnets and field coils to provide stronger starting torque, along with high quality brushes for longer service life. The housing is double sealed to help protect internal components from moisture and corrosion, a key requirement for marine duty cycles. This starter is sold on a no-core basis, meaning no used core return is required. A matching replacement solenoid, Sierra 18-5837, is available separately if the solenoid needs to be serviced independently of the starter motor.

Because the 18-5911 mounts on the bottom with a straight across bolt pattern, it is intended as a direct fit for GM-based marine engines using that mounting configuration within the 100-245 HP, 1970-1978 range. Every Sierra part is backed by Sierra's Industry Leading Customer Satisfaction Warranty, which covers defects in workmanship and materials for the useful life of the product.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-5911
• Product Type: Starter (Heavy-Duty)
• Core Requirement: No Core
• Engine Application: GM Engines
• Horsepower Range: 100-245 HP
• Model Years: 1970-1978
• Mounting: Bottom Mount, Straight Across Bolt Pattern
• Rotation: Standard Clockwise
• Marine Standards Compliance: SAE J1171, ISO 8846
• Housing: Double Sealed
• Replacement Solenoid: 18-5837
• Weight: 19.98 pounds

Fitment

• GM engines, bottom mount, straight across bolt pattern
• 100-245 HP
• 1970-1978

Replaces (OEM)

• 981078
• 982121
• 983444
• 983790
• 985966

Frequently Asked Questions

What engines does the Sierra 18-5911 starter fit? The 18-5911 is designed for GM engines using a bottom mount with a straight across bolt pattern, covering the 100-245 HP range for model years 1970-1978.

Does the 18-5911 require a core return? No, this starter is sold on a no-core basis, so there is no need to return a used starter core.

What is the rotation direction of this starter? Standard clockwise rotation is used on the Sierra 18-5911 heavy-duty starter.

Which OEM part numbers does the 18-5911 replace? It replaces OEM numbers 981078, 982121, 983444, 983790, and 985966.

How much does the 18-5911 starter weigh? The Sierra 18-5911 weighs 19.98 pounds.

What marine safety standards does this starter meet? It is built to meet SAE J1171 and ISO 8846 marine ignition-protection standards, which govern electrical equipment safety around fuel vapors on boats.

Is a solenoid included with the 18-5911 starter? The starter itself does not include a listed solenoid in the box; the matching replacement solenoid for the 18-5911 is Sierra part 18-5837, sold separately.

How is the 18-5911 mounted? This starter uses a bottom mount configuration with a straight across bolt pattern, matching the GM engine mounting layout it is designed for.

What makes this a heavy-duty starter? The 18-5911 uses high quality magnets and field coils for stronger starting torque, plus high quality brushes and a double sealed housing for longer service life in marine duty.

Is the Sierra 18-5911 covered by a warranty? Yes, the 18-5911 is covered under Sierra's Industry Leading Customer Satisfaction Warranty, which covers defects in workmanship and materials for the useful life of the product.

Why is the housing on the 18-5911 double sealed? The double sealed housing on this starter helps keep moisture out of the internal components, which is important for the wet, corrosive conditions found in marine engine compartments.