{"product_id":"sierra-18-5431-distributor-rotor-for-mercury-mercruiser-gm-v-8-thunderbolt-iv-v-hei-ignition-replaces-13524a5","title":"Sierra 18-5431 Rotor Assembly for MerCruiser GM V-8 Thunderbolt IV \u0026 V Ignition, Replaces 13524A5","description":"\u003cp\u003eThe Sierra 18-5431 Rotor Assembly is a direct-fit distributor rotor engineered for MerCruiser GM V-8 engines equipped with Thunderbolt IV and Thunderbolt V ignition systems. It is built to Sierra's MAGFORCE ignition standards, which are designed to be electronics friendly, protecting onboard electronic devices and engine controls from RFI and EMI interference while still delivering the voltage the ignition system needs to fire reliably. The rotor features moisture-proof, molded distributor insulators and a high-quality conductive center carrier reinforcement that maintains conductor integrity over years of service in the harsh marine environment.\u003c\/p\u003e\u003cp\u003eThis rotor is confirmed to fit several MerCruiser V-8 engine configurations, including the 500 Bulldog 540\/V-8, the 575 540\/V-8, and the 800 SC 572\/V-8, each identified by specific serial number ranges. It ships as a single-piece rotor assembly and is intended as a direct replacement for the original equipment rotor in these ignition systems, restoring correct spark distribution during a tune-up or ignition system service.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-5431\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Rotor Assembly\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits:\u003c\/strong\u003e GM V-8 Engines With Thunderbolt IV \u0026amp; V Ignition\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 13524T1, 13524A5\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExterior Finish:\u003c\/strong\u003e Machined\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.17 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNumber of Items:\u003c\/strong\u003e 1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999319302\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMerCruiser 500 Bulldog 540\/V-8, 1990-2001, serial numbers C577003 - M050281\u003c\/li\u003e\n\u003cli\u003eMerCruiser 575 540\/V-8, 1986-1992, serial numbers A677429 - D763716\u003c\/li\u003e\n\u003cli\u003eMerCruiser 800 SC 572\/V-8, 1993-1998, serial numbers D763836 and up\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e13524T1\u003c\/li\u003e\n\u003cli\u003e13524A5\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-5431 rotor assembly fit?\u003c\/strong\u003e The 18-5431 is designed for GM V-8 engines equipped with Thunderbolt IV and Thunderbolt V ignition systems, and it is confirmed to fit the MerCruiser 500 Bulldog 540\/V-8 (1990-2001), the 575 540\/V-8 (1986-1992), and the 800 SC 572\/V-8 (1993-1998).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs 18-5431 a direct OEM replacement?\u003c\/strong\u003e Yes, part number 18-5431 is designed as a direct replacement rotor and cross-references to OEM numbers 13524T1 and 13524A5.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the rotor assembly weigh?\u003c\/strong\u003e The Sierra 18-5431 rotor assembly weighs 0.17 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat does the OEM number 13524A5 correspond to?\u003c\/strong\u003e 13524A5 is one of the OEM cross-reference numbers for the Sierra 18-5431 rotor assembly, along with 13524T1.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many rotors come in the package?\u003c\/strong\u003e The 18-5431 ships as a single rotor assembly, with one item per package.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat finish does the 18-5431 rotor have?\u003c\/strong\u003e The rotor has a machined exterior finish.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-5431 rotor protect onboard electronics from interference?\u003c\/strong\u003e Yes, Sierra's MAGFORCE ignition components, including the 18-5431 rotor, are engineered to be electronics friendly and shield RFI and EMI from onboard electronic devices and engine controls.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-5431 rotor fit non-Thunderbolt ignition systems?\u003c\/strong\u003e No, the 18-5431 is specified for GM V-8 engines with Thunderbolt IV and Thunderbolt V ignition systems only.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat serial number range applies to the MerCruiser 800 SC 572\/V-8 fitment?\u003c\/strong\u003e For the MerCruiser 800 SC 572\/V-8, the Sierra 18-5431 rotor fits engines with serial numbers D763836 and up.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-5431 rotor moisture resistant?\u003c\/strong\u003e Yes, the rotor uses moisture-proof, molded distributor insulators to help prevent moisture-related ignition failures in marine use.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat serial numbers apply to the 575 540\/V-8 fitment for part 18-5431?\u003c\/strong\u003e On the MerCruiser 575 540\/V-8, the 18-5431 rotor fits engines within serial numbers A677429 through D763716.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when I order the 18-5431?\u003c\/strong\u003e Ordering the Sierra 18-5431 includes one rotor assembly; it is sold individually with no additional components.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988216688859,"sku":"SIE-18-5431","price":11.02,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-5431_lg__32077.1558129108.500.750.jpg?v=1785188972","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-5431-distributor-rotor-for-mercury-mercruiser-gm-v-8-thunderbolt-iv-v-hei-ignition-replaces-13524a5","provider":"Good Vibes Marina","version":"1.0","type":"link"}