Sierra Rotor & Trigger Wheel AP-2296 SIE-18-5432

Sierra SIE-18-5432 is a rotor and trigger wheel assembly for GM V6 marine engines equipped with Thunderbolt IV and Thunderbolt V HEI ignition systems. This ignition-service component is used in the distributor assembly and is designed as a replacement for selected MerCruiser V6 Thunderbolt applications. Sierras AP-2296 designation is commonly associated with this rotor and trigger wheel assembly.

Key Features

• Rotor and trigger wheel assembly
• Sierra part number: 18-5432
• AP-2296 application reference
• For GM V6 marine engines with Thunderbolt IV & V HEI ignition
• Distributor ignition service replacement part
• Common Sierra replacement for earlier Sierra 18-5401 listings.

Engine Compatibility
Commonly listed for GM V6 marine engines using MerCruiser Thunderbolt IV and Thunderbolt V HEI ignition systems. Aftermarket sources also describe it for MerCruiser V6 applications in the 225390 HP range where this distributor ignition setup is used. Fitment should be confirmed by engine model, ignition type, and the installed distributor components before ordering.

Serial Number Fitment Notice
Fitment should be confirmed by engine model and serial number, along with the installed Thunderbolt distributor ignition type, before ordering. Rotor and trigger wheel parts are ignition-specific and should be matched to the distributor application rather than by engine family alone.

When This Part Needs Replacement
Replace when ignition performance becomes inconsistent, the rotor shows burning or wear, the trigger wheel is damaged, or distributor service reveals corrosion, cracking, or abnormal wear. Rotor and trigger wheel components are critical to ignition timing and spark delivery, so worn parts can cause misfire, hard starting, or poor engine performance.

Installation Notes
Install only on GM V6 marine engines using the correct Thunderbolt IV or V HEI distributor setup. Confirm the replacement matches the existing rotor and trigger wheel assembly before installation. Because this is an ignition-specific distributor part, checking the original part number and distributor configuration is the safest way to avoid ordering the wrong assembly.

Alternate / Superseded Part Numbers

• AP-2296
• 18-5432
• Sierra 18-5401
• Mercury MerCruiser 13524A6
• Mercury MerCruiser 13524Q06
• Mercury MerCruiser 13524A4
• Mercury MerCruiser 19405A4
• Mercury MerCruiser 90576A4
• Mallory 9-29218
• GLM 71070

Parts Desk Insight
This part is best matched by ignition system first, not just by engine size. Sierra 18-5432 is consistently tied to GM V6 Thunderbolt IV and V HEI applications, so confirming the distributor setup is more important than relying on horsepower alone. That is especially important on older MerCruiser ignition parts where several similar-looking rotor assemblies exist.

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