{"product_id":"sierra-18-5389-distributor-cap-for-ford-gm-v-8-marine-engines-replaces-crusader-3000121-mercury-marine-393-4988t","title":"Sierra Distributor Cap 18-5389, Replaces Mercury Marine 393-4988T, for Ford \u0026 GM V-8 Engines","description":"\u003cp\u003eThe Sierra 18-5389 Distributor Cap is a metal, machined-finish replacement distributor cap built for Ford and GM V-8 marine engines running Autolite or Mercury ignition systems. It uses a twist-on closure for a secure, positive seal against moisture and vibration, both common failure points for marine ignition components operating in a harsh onboard environment. The white housing protects the internal contacts while distributing spark to each cylinder in firing order, and the cap is engineered to meet or exceed the specifications of the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003eThis cap is a straightforward tune-up and ignition-maintenance item, suited for scheduled replacement as part of routine engine service or as a direct fix for a cracked, arced, or corroded cap. It ships as a single component and is intended to be matched with a compatible rotor and ignition coil for the engine it is installed on.\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 18-5389\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Metal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExterior Finish:\u003c\/strong\u003e Machined\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eClosure Type:\u003c\/strong\u003e Twist-On\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eItem Dimensions:\u003c\/strong\u003e 0.39 x 0.39 x 0.39 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.67 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatible Engines:\u003c\/strong\u003e Ford and GM V-8 engines with Autolite or Mercury ignitions\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999236678\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eFord V-8 marine engines with Autolite ignition\u003c\/li\u003e\n\u003cli\u003eGM V-8 marine engines with Autolite or Mercury ignition\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e393-4988T2\u003c\/li\u003e\n\u003cli\u003eCrusader 3000121\u003c\/li\u003e\n\u003cli\u003eMercury Marine 393-4988T\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-5389 distributor cap fit?\u003c\/strong\u003e The 18-5389 fits Ford and GM V-8 marine engines equipped with Autolite or Mercury ignition systems.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-5389 cap a direct replacement for a Mercury Marine cap?\u003c\/strong\u003e Yes, this Sierra cap cross-references to Mercury Marine 393-4988T and 393-4988T2, along with Crusader 3000121, so it is a direct equivalent for those OEM part numbers.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the Sierra 18-5389 distributor cap made from?\u003c\/strong\u003e It has a metal body with a machined exterior finish and a white housing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow does the cap attach to the distributor housing?\u003c\/strong\u003e The 18-5389 uses a twist-on closure type rather than screw-down clips.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-5389 distributor cap weigh?\u003c\/strong\u003e It weighs 0.67 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the dimensions of this distributor cap?\u003c\/strong\u003e The Sierra 18-5389 measures 0.39 x 0.39 x 0.39 inches.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-5389 come with a rotor or gasket?\u003c\/strong\u003e No, the 18-5389 is supplied as the distributor cap only; it does not include a rotor or gasket.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this a genuine Sierra part or an aftermarket copy?\u003c\/strong\u003e The 18-5389 is a genuine Sierra part, manufactured to meet or exceed the specifications of the original equipment component it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-5389 work on an engine with points-type ignition?\u003c\/strong\u003e The 18-5389 is designed for Ford and GM V-8 engines with Autolite or Mercury ignitions; check your existing ignition type before ordering, as it is not listed for other ignition configurations.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if my distributor cap needs replacing?\u003c\/strong\u003e Common signs include visible cracking, carbon tracking, corrosion on the internal contacts, or a rough-running engine; the 18-5389 is intended as a direct replacement when the original cap shows this kind of wear.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-5389 distributor cap?\u003c\/strong\u003e The UPC for the Sierra 18-5389 distributor cap is 030999236678.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988212527323,"sku":"SIE-18-5389","price":30.35,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-5389_lg__53264.1558127569.500.750.jpg?v=1785188433","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-5389-distributor-cap-for-ford-gm-v-8-marine-engines-replaces-crusader-3000121-mercury-marine-393-4988t","provider":"Good Vibes Marina","version":"1.0","type":"link"}