{"product_id":"mercury-mercruiser-864579-cooling-hose","title":"Mercury MerCruiser 864579 Cooling System Hose – Check Valve to Thermostat Housing","description":"\u003csection class=\"product-description\"\u003e\n\n\u003ch2\u003eMercury MerCruiser 864579 – Cooling System Hose\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003ePart Number:\u003c\/strong\u003e 864579 \/ 32-864579\u003cbr\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Mercury \/ MerCruiser\u003cbr\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e Molded cooling-system hose\u003cbr\u003e\n\u003cstrong\u003ePosition:\u003c\/strong\u003e Check valve to thermostat housing\u003cbr\u003e\n\u003cstrong\u003eGTIN:\u003c\/strong\u003e 745061545793\u003c\/p\u003e\n\n\u003ch2\u003eOverview\u003c\/h2\u003e\n\u003cp\u003eThis is a genuine Mercury MerCruiser cooling-system hose that connects the check valve to the thermostat housing on selected MerCruiser gasoline inboard and sterndrive engines. It is a direct-fit molded replacement that follows the original routing and connection geometry for the engines listed below.\u003c\/p\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eGenuine Mercury \/ MerCruiser OEM replacement part\u003c\/li\u003e\n\u003cli\u003eMolded hose designed to match the original routing and connection points exactly\u003c\/li\u003e\n\u003cli\u003eConnects the check valve to the thermostat housing in the standard cooling circuit\u003c\/li\u003e\n\u003cli\u003eBuilt for the demands of closed-cooled and raw-water marine cooling systems\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eCompatible Applications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eMerCruiser 4.3L MPI Alpha \/ Bravo\u003c\/li\u003e\n\u003cli\u003eMerCruiser 5.0L MPI Alpha \/ Bravo\u003c\/li\u003e\n\u003cli\u003eMerCruiser 350 MAG MPI 5.7L Alpha \/ Bravo\u003c\/li\u003e\n\u003cli\u003eMerCruiser 350 MAG MPI Horizon\u003c\/li\u003e\n\u003cli\u003eMerCruiser 377 MAG MPI\u003c\/li\u003e\n\u003cli\u003eMerCruiser MX 6.2L MPI\u003c\/li\u003e\n\u003cli\u003eSelected 357 \/ 383 MAG Stroker configurations\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSerial number fitment notice:\u003c\/strong\u003e Cooling-system hose layouts vary by engine model, serial range, drain system, and Alpha\/Bravo configuration. Always confirm the engine serial number and verify part number 864579 \/ 32-864579 in the applicable cooling-system diagram before ordering.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eSystem \u0026amp; Diagram Position\u003c\/h2\u003e\n\u003cp\u003eParts diagrams identify 864579 within the \u003cstrong\u003estandard cooling system\u003c\/strong\u003e assembly, specifically on 5.0L MPI, 350 MAG MPI, and MX 6.2L MPI engines. It occupies the position between the check valve outlet and the thermostat-housing inlet — a critical junction that routes coolant through the thermostat circuit.\u003c\/p\u003e\n\n\u003ch2\u003eWhen to Replace\u003c\/h2\u003e\n\u003cp\u003eReplace this hose if it is cracked, hardened, swollen, soft, chafed, or shows any damage at the connection points. Aging cooling hoses can develop leaks or internal restrictions that disrupt proper coolant circulation and engine temperature control — even a small leak at this location can affect thermostat function.\u003c\/p\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eAllow the engine to cool completely before beginning any cooling-system service\u003c\/li\u003e\n\u003cli\u003eNote the original hose routing and clamp positions before removing the old hose\u003c\/li\u003e\n\u003cli\u003eInspect the check valve, thermostat housing fitting, and existing clamps while the hose is off\u003c\/li\u003e\n\u003cli\u003eInstall the new hose and tighten clamps to the torque specified in the engine service manual\u003c\/li\u003e\n\u003cli\u003eRun the engine and inspect carefully for leaks at both connection points before returning the vessel to service\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eCross-Reference \/ Alternate Part Numbers\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eMercury \/ MerCruiser: 864579\u003c\/li\u003e\n\u003cli\u003eMercury catalog reference: 32-864579\u003c\/li\u003e\n\u003cli\u003eSearch reference: 32864579\u003c\/li\u003e\n\u003cli\u003eGTIN: 745061545793\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eDimensions \u0026amp; Weight\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eWeight: approx. 200 g (0.44 lb) — best estimate for a molded marine cooling hose of this type\u003c\/li\u003e\n\u003cli\u003eRefer to the MerCruiser parts diagram for exact hose routing dimensions\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eParts Desk Insights\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eBest Use Case:\u003c\/strong\u003e This hose is the right part when a cooling-system inspection on a MerCruiser V6 or V8 MPI engine reveals a failed or degraded hose at the check valve-to-thermostat housing junction. It's a common service item on higher-hour engines and a worthwhile replacement during any thermostat or raw-water pump service.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCommon Issues:\u003c\/strong\u003e The most important step is confirming position in the diagram before ordering — nearby MerCruiser hoses can look nearly identical but connect different components. Match by part number (864579 \/ 32-864579) and engine serial number, not by appearance alone. If the thermostat housing or check valve fittings show corrosion or damage, plan to address those at the same time to avoid a repeat repair.\u003c\/p\u003e\n\n\u003ch2\u003eRelated Products\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/8131426811940\"\u003eMercury MerCruiser 3.0L Drain System Adapter Assembly – 22-862605T1\u003c\/a\u003e — related MerCruiser cooling\/drain system component\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/8131408068644\"\u003eMercury Water Distributor Thermostat Housing Gasket – 27-475901\u003c\/a\u003e — replace the thermostat housing gasket while servicing this area\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/8131397025828\"\u003eMercury Cooling Hose – 160211\u003c\/a\u003e — companion cooling hose for MerCruiser applications\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/products\/8131431858212\"\u003eMercury Quicksilver Extended Life Coolant\/Antifreeze 877770K1\u003c\/a\u003e — top up coolant when servicing the cooling system\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003c\/section\u003e","brand":"MERC","offers":[{"title":"Default Title","offer_id":51324692267044,"sku":"864579","price":42.74,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0743\/5799\/7604\/files\/images_f725b1e6-487c-4ee0-b9a0-a68cbc782edc.jpg?v=1788155435","url":"https:\/\/marisolmarine.com\/products\/mercury-mercruiser-864579-cooling-hose","provider":"Marisol Marine Company","version":"1.0","type":"link"}