Sierra Distributor Rotor 18-5418 for MerCruiser 110/120/140 I/O Ignition, Replaces Mercury Marine 58217

The Sierra 18-5418 is a distributor rotor built for MerCruiser stern drive ignition systems using a contact-controlled distributor with standard rotation (this rotor is not for Thunderbolt ignition applications). It is the rotor position specified in the MerCruiser tune-up parts breakdown for the 110, 120, and 140 model engines, all of which use a 4-cylinder inline engine (153 cid or 181 cid) paired with a points-and-condenser style distributor. The rotor mounts inside the distributor cap and rotates with the distributor shaft to direct spark from the coil to each spark plug tower in firing order, so a worn, cracked, or burned rotor tip is a common cause of misfires, hard starting, or a rough idle on these engines.

As part of a complete tune-up, the 18-5418 rotor is typically replaced alongside the contact set, distributor cap, coil, and spark plug wires that share the same engine application. It is sold as a direct-fit component for the MerCruiser 110, 120, and 140 model engines within the serial number ranges covered by those models, and it cross-references to OEM rotors used by Chris-Craft, Mercury Marine, and OMC on the same ignition platform.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-5418
• Product Type: Distributor Rotor
• Application: Contact-controlled distributor, standard rotation, excludes Thunderbolt ignition
• Fits Engines: 153 cid L4, 181 cid L4
• Fits Models: MerCruiser 110, 120, 140
• Weight: 0.03 pounds
• Product Dimensions: 1 x 1 x 2 inches
• UPC: 030999236708

Fitment

• MerCruiser 110, 153 cid L4, years 1963-1966, serial number range 1537370-2044033
• MerCruiser 120, 153 cid L4, years 1964-1986, serial number range 1666601-B531853
• MerCruiser 140, 181 cid L4, years 1968-1986, serial number range 2508261-B450800

Replaces (OEM)

• Chris-Craft 16.69-00051
• Mercury Marine 58217
• OMC 384735

Frequently Asked Questions

What engines does the Sierra 18-5418 rotor fit? The 18-5418 rotor fits MerCruiser 110, 120, and 140 model engines, which use a 153 cid or 181 cid L4 engine paired with a contact-controlled distributor.

Will this rotor work with a Thunderbolt ignition system? No, the 18-5418 rotor is built for contact-controlled distributors with standard rotation and is not intended for Thunderbolt ignition applications.

What is the OEM equivalent of Sierra part 18-5418? Sierra 18-5418 cross-references to Chris-Craft 16.69-00051, Mercury Marine 58217, and OMC 384735, making it a direct replacement for those OEM rotors.

How much does the 18-5418 rotor weigh? The Sierra 18-5418 distributor rotor weighs 0.03 pounds.

What are the dimensions of this rotor? The 18-5418 rotor measures 1 x 1 x 2 inches.

What serial number range applies to the MerCruiser 120 with this rotor? For the MerCruiser 120, the 18-5418 rotor applies to serial number range 1666601 through B531853, covering years 1964-1986.

Is this rotor sold individually or as part of a kit? The 18-5418 is sold as an individual rotor; it is one of the components listed in the MerCruiser tune-up parts breakdown alongside the contact set, distributor cap, coil, and spark plug wires.

What years does the 18-5418 rotor cover for the MerCruiser 110? For the MerCruiser 110, the 18-5418 rotor covers model years 1963-1966, within serial number range 1537370-2044033.

Does the 18-5418 rotor fit the MerCruiser 140? Yes, the MerCruiser 140 (181 cid L4) uses the 18-5418 rotor for model years 1968-1986, serial number range 2508261-B450800.

What symptoms indicate a distributor rotor needs replacement? A worn, cracked, or burned rotor tip on the ignition system that the 18-5418 fits can cause misfires, hard starting, or a rough idle, since the rotor directs spark from the coil to each spark plug in firing order.

Is the Sierra 18-5418 a genuine or aftermarket part? The 18-5418 is a Sierra-brand replacement rotor manufactured to match the fit and function of the original Chris-Craft, Mercury Marine, and OMC rotors it cross-references.