FASWORX 392-805570A2 Ignition Coil for MerCruiser Thunderbolt IV/V HEI Engines Fits 4.3 5.0 5.7 6.2 V6 V8 | Replaces 392-7803A4 72115, 40511 & 18-5438

The FASWORX 392-805570A2 Marine Ignition Coil is a direct-replacement ignition coil intended for MerCruiser engines equipped with Thunderbolt IV and Thunderbolt V HEI ignition systems. This coil performs the critical role of converting battery voltage into the high-voltage output required for spark generation, restoring proper ignition performance when the original coil has failed or weakened. This ignition coil replaces Mercury Marine OEM part numbers 392-805570A2 and 392-7803A4 and is commonly cross-referenced in marine catalogs to Sierra 18-5438. Installers typically identify this component by OEM number, Thunderbolt ignition type, or HEI configuration rather than by engine serial alone. Proper replacement helps maintain consistent ignition timing and reliable engine operation in marine environments.

• Designed to replace the factory marine ignition coil used on MerCruiser Thunderbolt IV and Thunderbolt V HEI ignition systems.
• Replaces Part# 18-5438, 392-805570A2, 392-7803A4, 392-805570A1, 72115, 40511, 9-29701, 64570, RL5438.
• Used on GM-based MerCruiser gasoline engines equipped with Thunderbolt IV or V HEI ignition systems, including typical V6 and V8 inboard and sterndrive configurations
• Built with the correct primary and secondary terminals and mounting configuration to match OEM coil layout, allowing straightforward replacement without modification.
• FASWORX replacement components are engineered to mirror OEM form and function, providing a reliable aftermarket solution for maintenance and ignition system service.