Sierra Ignition Coil 18-99598 - Replaces OMC 502886, 582303, 582303-K, 581826 - Johnson/Evinrude 3/6 Cylinder 1972-1978

The Sierra 18-99598 is a replacement ignition coil built for Johnson and Evinrude Cross Flow outboard engines. The ignition coil is the component that steps up battery voltage into the high-voltage spark needed to fire the spark plugs, and a weak or failed coil is a common cause of hard starting, misfiring, rough idle, or a no-spark condition. This coil is a plug-in installation with a male connector, and it includes the plug wire and hardware needed to complete the swap, so no separate wiring purchase is required.

Sierra 18-99598 is built to serve as a direct equivalent for the original equipment coil used on Cross Flow engines, cross-referencing to OMC part numbers 502886, 582303, 582303-K, and 581826. It fits 3-cylinder Cross Flow engines rated 65, 70, and 75 HP from 1972-1978, as well as 6-cylinder Cross Flow engines rated 150 to 235 HP from 1976-1978. Before ordering, confirm the part number against your engine's original coil or your engine manufacturer's recommended part number, since coil designs varied across these engine families.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-99598
• Product Type: Ignition Coil
• Compatible Engine Family: Johnson/Evinrude Cross Flow
• Cylinder Configuration: 3 Cylinder and 6 Cylinder
• Horsepower Range (3 Cylinder): 65, 70, 75 HP
• Horsepower Range (6 Cylinder): 150 to 235 HP
• Model Years (3 Cylinder): 1972-1978
• Model Years (6 Cylinder): 1976-1978
• Connector Gender: Male
• Installation Type: Plug-in
• Included Components: Plug wire and hardware
• Weight: 0.7 pounds
• OEM Cross Reference: 502886, 582303, 582303-K, 581826

Fitment

• Johnson/Evinrude Cross Flow, 65, 70, 75 HP (3 cylinder), 1972-1978
• Johnson/Evinrude Cross Flow, 150 to 235 HP (6 cylinder), 1976-1978

Replaces (OEM)

• 502886
• 582303
• 582303-K
• 581826

Frequently Asked Questions

What engines does the Sierra 18-99598 ignition coil fit? The Sierra 18-99598 fits Johnson/Evinrude Cross Flow outboard engines, specifically 65, 70, and 75 HP 3-cylinder models from 1972-1978 and 150 to 235 HP 6-cylinder models from 1976-1978.

What OEM part numbers does this coil replace? This coil cross-references to OMC part numbers 502886, 582303, 582303-K, and 581826, so it can be used as a direct equivalent for any of those original part numbers.

Does the Sierra 18-99598 include the wiring needed for installation? Yes, the plug wire and mounting hardware are included, so the coil is ready to install without needing to source separate wiring.

How does this coil connect to the ignition harness? It uses a male connector and is a plug-in installation, meaning it connects directly into the existing harness without splicing.

How much does the 18-99598 ignition coil weigh? The Sierra 18-99598 ignition coil weighs 0.7 pounds.

Is this coil an aftermarket or genuine OEM part? The Sierra 18-99598 is an aftermarket replacement designed to serve as a direct equivalent to the original Johnson/Evinrude coil, cross-referencing OEM numbers 502886, 582303, 582303-K, and 581826.

What are the symptoms of a failing ignition coil on a Cross Flow engine? Hard starting, rough idle, misfiring, and a complete loss of spark are common signs that the ignition coil on a Johnson/Evinrude Cross Flow engine, such as the one replaced by the 18-99598, needs replacement.

Will the 18-99598 fit a 6-cylinder Cross Flow engine as well as a 3-cylinder engine? Yes, this part fits both configurations: 3-cylinder Cross Flow engines rated 65-75 HP from 1972-1978 and 6-cylinder Cross Flow engines rated 150-235 HP from 1976-1978.

Should I confirm the coil against my engine's original part number before ordering? Yes, since coil designs can vary within the Cross Flow engine family, it is recommended to check the 18-99598 against your engine's original coil or manufacturer-recommended part number before ordering.

Is the 18-99598 sold as a single coil or a set? The 18-99598 is sold as a single ignition coil unit, complete with plug wire and hardware.