Sierra 18-99483 Trigger Disc for Mercury Mariner 6-Cylinder Outboards, Replaces MC# 393-4313

The Sierra 18-99483 is an ignition trigger disc engineered for Mercury Mariner 6-cylinder outboard engines. The trigger disc is a core ignition-timing component that works with the engine's stator and triggering assembly to signal spark timing to the ignition module as the flywheel rotates. Precise, consistent triggering is essential for correct spark timing across the RPM range, so a worn, cracked, or out-of-spec trigger disc can cause misfires, hard starting, rough idle, or a no-spark condition.

This trigger disc is a direct replacement for the discontinued Mercury MC# 393-4313 trigger disc, giving owners of older Mercury Mariner 6-cylinder outboards a currently available part to restore correct ignition timing without sourcing an obsolete factory part. It is sized to fit into the existing ignition trigger assembly on applicable 6-cylinder Mercury Mariner powerheads, and installation follows the same mounting position as the original disc it replaces.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-99483
• Application: Mercury Mariner 6-Cylinder Outboard Engines
• Product Dimensions: 6 x 6 x 1.5 inches
• Weight: 0.02 pounds
• UPC: 808282395391

Fitment

Fits Mercury Mariner 6-cylinder outboard engines that originally used the Mercury MC# 393-4313 trigger disc.

Replaces (OEM)

• MC# 393-4313
• 1344313S

Frequently Asked Questions

What does the Sierra 18-99483 trigger disc fit? The Sierra 18-99483 trigger disc fits Mercury Mariner 6-cylinder outboard engines that originally used the Mercury MC# 393-4313 trigger disc.

Does 18-99483 replace Mercury MC# 393-4313? Yes, the Sierra 18-99483 is a direct replacement for the Mercury MC# 393-4313 trigger disc, which is no longer available from Mercury.

What is a trigger disc used for on an outboard engine? A trigger disc rotates with the flywheel and signals the ignition module when to fire each cylinder's spark, so it directly controls ignition timing on the outboard's 6-cylinder ignition system.

What happens if the trigger disc is worn or damaged? A worn or cracked trigger disc like the one replaced by Sierra 18-99483 can cause incorrect spark timing, resulting in misfires, hard starting, a rough idle, or a complete loss of spark on affected cylinders.

How much does the 18-99483 trigger disc weigh? The Sierra 18-99483 trigger disc weighs 0.02 pounds.

What are the dimensions of this trigger disc? The trigger disc measures 6 x 6 x 1.5 inches.

Is this trigger disc a genuine Mercury part or an aftermarket replacement? Sierra 18-99483 is an aftermarket replacement built to replace the discontinued Mercury MC# 393-4313 trigger disc, sourced for owners who can no longer buy the original factory part.

Is the CDI 1344313S the same part as Sierra 18-99483? Sierra 18-99483 corresponds to the same trigger disc cataloged elsewhere as CDI part number 1344313S, both serving as replacements for Mercury MC# 393-4313.

Can I install the 18-99483 trigger disc myself? The trigger disc mounts in the same position as the original Mercury MC# 393-4313 disc it replaces, so it is typically installed by removing and reinstalling the trigger assembly at the flywheel; a service manual for the specific 6-cylinder Mercury Mariner engine should be used to confirm torque and timing procedures.

What ignition system does this trigger disc work with? The 18-99483 works with the ignition trigger and stator assembly on Mercury Mariner 6-cylinder outboard engines to time spark delivery to each cylinder.

Does the UPC on this part help confirm I am ordering the right one? Yes, Sierra 18-99483 is identified by UPC 808282395391, which can be used to confirm you are ordering the correct trigger disc for your Mercury Mariner 6-cylinder outboard.