{"product_id":"mercury-mercruiser-quicksilver-cooling-hose-864578","title":"Mercury MerCruiser Quicksilver Cooling Hose 864578 — Drain Fitting to Check Valve","description":"\u003ch2\u003eMercury MerCruiser Quicksilver Cooling Hose — OEM Part 864578\u003c\/h2\u003e\u003cp\u003eThis genuine OEM cooling hose connects the drain fitting to the check valve in MerCruiser's raw-water cooling and drain system. Engineered to Mercury Marine factory specification, it maintains the correct routing, sealing, and flow path that MerCruiser's cooling circuit depends on. If your hose is cracked, hardened, swollen, or weeping at either end, this is the correct OEM replacement — position-specific and direct-fit.\u003c\/p\u003e\u003ch2\u003ePart Information\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Part Number:\u003c\/strong\u003e 864578\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMercury Reference:\u003c\/strong\u003e 32-864578\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Mercury \/ Quicksilver\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOfficial Product Type:\u003c\/strong\u003e Cooling-system hose\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSystem:\u003c\/strong\u003e Raw-water \/ standard cooling and drain system\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDiagram Position:\u003c\/strong\u003e Drain fitting to check valve\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGTIN \/ UPC:\u003c\/strong\u003e 745061545786\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatible Applications\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eMerCruiser 5.0L MPI Alpha \/ Bravo — 5.0L (305 cu. in.) V8 GM engine family with Alpha 7-point drain cooling system\u003c\/li\u003e\n\u003cli\u003eSelected MerCruiser gasoline inboard and sterndrive engines using the standard raw-water cooling and drain layout\u003c\/li\u003e\n\u003cli\u003eConfirm fitment via engine serial number and cooling-system diagram before ordering — MerCruiser used multiple hose layouts depending on engine family, drive configuration, and drain-system design\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRelated Parts\u003c\/h2\u003e\u003cul\u003e\u003cli\u003e\n\u003ca href=\"\/products\/mercury-mercruiser-864579-cooling-system-hose-check-valve-to-thermostat-housing\"\u003eMercury MerCruiser 864579 — Check Valve to Thermostat Housing Hose\u003c\/a\u003e (adjacent hose in the same cooling diagram)\u003c\/li\u003e\u003c\/ul\u003e\u003ch2\u003eWhen to Replace\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eHose is cracked, hardened, or swollen\u003c\/li\u003e\n\u003cli\u003eChafing or wear visible near the fittings\u003c\/li\u003e\n\u003cli\u003eLeaking or seeping at either connection point\u003c\/li\u003e\n\u003cli\u003eHose shows internal restriction or collapses under suction\u003c\/li\u003e\n\u003cli\u003ePart of a scheduled cooling-system service or pre-season inspection\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eAllow the engine to cool fully before beginning service\u003c\/li\u003e\n\u003cli\u003eNote the existing hose routing and clamp positions before removal\u003c\/li\u003e\n\u003cli\u003eInspect the drain fitting, check valve, and hose clamps while the hose is off\u003c\/li\u003e\n\u003cli\u003eVerify the cooling system is leak-free after installation before returning the engine to service\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eService Interval\u003c\/h2\u003e\u003cp\u003eInspect annually as part of spring commissioning. Replace at the first sign of cracking, hardening, or seepage — or proactively every 3–5 years as part of a full cooling-system hose refresh.\u003c\/p\u003e\u003ch2\u003eTechnical FAQ\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eWhat is the difference between 864578 and 864579?\u003c\/strong\u003e\u003cbr\u003eThese two hoses appear side-by-side in the same MerCruiser cooling diagram but serve different connections. 864578 runs from the drain fitting to the check valve; \u003ca href=\"\/products\/mercury-mercruiser-864579-cooling-system-hose-check-valve-to-thermostat-housing\"\u003e864579\u003c\/a\u003e continues from the check valve to the thermostat housing. They are not interchangeable.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I confirm this hose fits my engine?\u003c\/strong\u003e\u003cbr\u003eMatch OEM part number 864578 to your engine serial number using the Mercury parts diagram for your specific engine family and drive configuration. Cooling hose layouts vary between model years and drain-system designs.\u003c\/p\u003e\u003ch2\u003eParts Desk Insights\u003c\/h2\u003e\u003cp\u003eThis hose is most often needed during spring commissioning or after winterization, when cooling hoses are inspected for hardening or cracking from thermal cycling. The most common customer mistake is ordering 864579 instead — the two hoses sit next to each other in the diagram and are easy to confuse. When replacing 864578, it’s worth checking \u003ca href=\"\/products\/mercury-mercruiser-864579-cooling-system-hose-check-valve-to-thermostat-housing\"\u003e864579\u003c\/a\u003e at the same time, since both hoses age at the same rate. Browse the full \u003ca href=\"\/collections\/mercury-mercruiser-and-quicksilver-cooling-system-parts\"\u003eMercury MerCruiser Cooling System Parts\u003c\/a\u003e collection for clamps, check valves, thermostats, and water pumps.\u003c\/p\u003e","brand":"MERC","offers":[{"title":"Default Title","offer_id":51324692234276,"sku":"864578","price":56.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0743\/5799\/7604\/files\/81844f52-d0ba-438c-8e25-7e5651b6bec3.png?v=1788200478","url":"https:\/\/marisolmarine.com\/products\/mercury-mercruiser-quicksilver-cooling-hose-864578","provider":"Marisol Marine Company","version":"1.0","type":"link"}