{"product_id":"sierra-18-5278-tune-up-kit-for-mercruiser-crusader-v-6-delco-est-ignition-replaces-mercruiser-850484t3-includes-distributor-cap-rotor","title":"Sierra 18-5278 V-6 Delco EST Ignition Tune-Up Kit, Replaces Mercruiser 850484T3","description":"\u003cp\u003eThe Sierra 18-5278 is an ignition tune-up kit engineered for V-6 engines equipped with a Delco EST ignition system. Tune-up kits like this one are used to restore reliable spark delivery during routine engine maintenance, replacing worn distributor components that can cause misfires, hard starting, or rough idle over time. The kit includes a distributor cap (18-5362) and rotor (18-5408), finished in white, giving the buyer the two core wear items needed for a complete distributor cap-and-rotor service in one package. Each Sierra product is built to meet or exceed the performance of the original equipment part it replaces, making this kit a straightforward drop-in service solution rather than a partial fix requiring separate part sourcing. Because ignition components are fit-specific, buyers should confirm part numbers against their engine before ordering to ensure proper fit. This kit is cross-referenced to multiple OEM and aftermarket part numbers, so it can be located under several different catalog listings depending on the engine manufacturer's documentation a buyer is working from.\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 18-5278\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Configuration:\u003c\/strong\u003e V-6\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIgnition System:\u003c\/strong\u003e Delco EST\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncluded Components:\u003c\/strong\u003e Distributor Cap (18-5362), Rotor (18-5408)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282105075\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.52 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e GLM 71820, Mallory 9-29321, Mercruiser 850484T3, Mercruiser 850484T1\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cp\u003eFor V-6 engines equipped with a Delco EST ignition system.\u003c\/p\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eGLM 71820\u003c\/li\u003e\n\u003cli\u003eMallory 9-29321\u003c\/li\u003e\n\u003cli\u003eMercruiser 850484T3\u003c\/li\u003e\n\u003cli\u003eMercruiser 850484T1\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-5278 tune-up kit fit?\u003c\/strong\u003e The 18-5278 is designed for V-6 engines running a Delco EST ignition system. Because ignition parts are fit-specific, confirm your engine's ignition system type against the part number before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included in the 18-5278 kit?\u003c\/strong\u003e This kit contains a distributor cap (Sierra 18-5362) and a rotor (Sierra 18-5408), giving you both core wear components needed for a distributor cap-and-rotor service in one package.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-5278 the same as Mercruiser 850484T3?\u003c\/strong\u003e Yes, the 18-5278 cross-references to Mercruiser 850484T3 and 850484T1, as well as GLM 71820 and Mallory 9-29321, so it can be ordered as a direct equivalent under any of those part numbers.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the distributor cap in this kit?\u003c\/strong\u003e The distributor cap and rotor included in the Sierra 18-5278 tune-up kit are white.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-5278 tune-up kit weigh?\u003c\/strong\u003e The Sierra 18-5278 ignition tune-up kit weighs 0.52 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-5278 meet OEM specifications?\u003c\/strong\u003e Sierra states that this product meets or exceeds the performance of the original equipment part it replaces, making it a direct service replacement rather than a generic substitute.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs Sierra 18-5278 genuine Sierra or a generic aftermarket part?\u003c\/strong\u003e The 18-5278 is a genuine Sierra-branded tune-up kit, manufactured to meet or exceed the original equipment component it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the difference between 18-5278 and other Sierra tune-up kits like 18-5280 or 18-5281?\u003c\/strong\u003e The 18-5278 is built specifically for V-6 Delco EST ignition systems, while 18-5280 covers In-Line 4 Delco EST engines and 18-5281 covers V-8 Delco EST engines. Matching the correct kit to your engine's cylinder configuration and ignition system is essential.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use the 18-5278 kit if my engine has a Prestolite Electronic ignition instead of Delco EST?\u003c\/strong\u003e No, the 18-5278 is built for Delco EST ignition systems on V-6 engines; a V-8 Prestolite Electronic engine would require a different kit (18-5279), since ignition components are not interchangeable across ignition system types.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers can I search to find the 18-5278 kit?\u003c\/strong\u003e The 18-5278 kit cross-references to GLM 71820, Mallory 9-29321, Mercruiser 850484T3, and Mercruiser 850484T1.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988205285595,"sku":"SIE-18-5278","price":36.44,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/18-5278__59619.1737889952.500.750.jpg?v=1785188318","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-5278-tune-up-kit-for-mercruiser-crusader-v-6-delco-est-ignition-replaces-mercruiser-850484t3-includes-distributor-cap-rotor","provider":"Good Vibes Marina","version":"1.0","type":"link"}