{"product_id":"merc-368","title":"MerCruiser 864509 Cooling Hose – Thermostat Housing to Lower Manifold","description":"\u003ch2\u003eMerCruiser 864509 – Molded Cooling Hose | Thermostat Housing to Lower Exhaust Manifold\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003ePart Number:\u003c\/strong\u003e 864509  |  \u003cstrong\u003eReference:\u003c\/strong\u003e 32-864509\u003cbr\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Mercury Marine\u003cbr\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e Molded Engine Cooling Hose\u003cbr\u003e\n\u003cstrong\u003eSystem:\u003c\/strong\u003e Closed Cooling\u003cbr\u003e\n\u003cstrong\u003ePosition:\u003c\/strong\u003e Thermostat Housing to Lower Exhaust Manifold\u003cbr\u003e\n\u003cstrong\u003eGTIN:\u003c\/strong\u003e 745061554573\u003c\/p\u003e\n\n\u003cp\u003eGenuine Mercury Marine replacement hose for the closed-cooling system on selected MerCruiser gasoline engines. This molded hose connects the thermostat housing to the lower exhaust manifold, forming a critical part of the closed-loop coolant circuit. Designed to maintain proper coolant flow and resist the heat and pressure demands of marine engine service.\u003c\/p\u003e\n\n\u003chr\u003e\n\n\u003ch3\u003eCompatible Applications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e5.0L \/ 305 CID V8 MerCruiser – selected closed-cooling configurations\u003c\/li\u003e\n\u003cli\u003e5.7L \/ 350 CID V8 MerCruiser – selected closed-cooling configurations\u003c\/li\u003e\n\u003cli\u003e6.2L \/ 377 CID V8 MerCruiser – selected closed-cooling configurations\u003c\/li\u003e\n\u003cli\u003e350 MAG \/ Horizon \/ 383 MAG Stroker – selected configurations\u003c\/li\u003e\n\u003cli\u003eAlpha, Bravo, Axius, inboard, and V-drive closed-cooling layouts where 864509 is specified\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eSerial Number Notice:\u003c\/strong\u003e Confirm your engine serial number and closed-cooling diagram before ordering. Mercury uses several similar molded hoses in the same assembly, and exact hose selection varies by engine family and cooling-system configuration.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003chr\u003e\n\n\u003ch3\u003eWhen to Replace\u003c\/h3\u003e\n\u003cp\u003eInspect this hose at every service and replace if you notice any of the following:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eCracking, hardening, or surface checking\u003c\/li\u003e\n\u003cli\u003eSwelling or soft spots along the hose body\u003c\/li\u003e\n\u003cli\u003eChafing or wear near clamp areas\u003c\/li\u003e\n\u003cli\u003eSeeping or active coolant leak at either connection\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eAlso inspect whenever servicing the thermostat housing, exhaust manifolds, or heat-exchanger system — these hoses are easiest to replace with the surrounding components already removed.\u003c\/p\u003e\n\n\u003chr\u003e\n\n\u003ch3\u003eInstallation Notes\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eAllow the engine to cool completely before beginning any cooling-system work\u003c\/li\u003e\n\u003cli\u003eNote original hose routing and clamp positions before removal\u003c\/li\u003e\n\u003cli\u003eInspect both connection points for corrosion or damage\u003c\/li\u003e\n\u003cli\u003eReplace deteriorated clamps or related sealing components at the same time\u003c\/li\u003e\n\u003cli\u003eRefill and bleed the closed-cooling system per the applicable MerCruiser service procedure\u003c\/li\u003e\n\u003cli\u003eRun the engine and inspect carefully for leaks before returning to service\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003chr\u003e\n\n\u003ch3\u003ePart Numbers \u0026amp; Cross-Reference\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMercury Marine:\u003c\/strong\u003e 864509\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMercury Reference:\u003c\/strong\u003e 32-864509\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGTIN:\u003c\/strong\u003e 745061554573\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eRelated Cooling Hoses\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eRelated lower-manifold hose: 864508 (not currently in store)\u003c\/li\u003e\n\u003cli\u003eUpper-manifold hose: \u003ca href=\"\/products\/11167580553252\"\u003eMercury MerCruiser Cooling Hose — 32-864552\u003c\/a\u003e\n\u003c\/li\u003e\n\u003cli\u003eStarboard manifold hose: \u003ca href=\"\/products\/11167580389412\"\u003eMerCruiser 864539 Cooling Hose – Thermostat Housing to Starboard Manifold\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003chr\u003e\n\n\u003ch3\u003eParts Desk Insights\u003c\/h3\u003e\n\u003cp\u003eThe defining identifier for 864509 is its \u003cstrong\u003elower manifold position\u003c\/strong\u003e in the thermostat-housing circuit. Several hoses in this assembly look nearly identical, so always cross-check against the closed-cooling diagram for your specific engine before ordering. The most common customer mistake is confusing this lower-manifold hose with the upper-manifold or heat-exchanger hoses nearby. If you're replacing this hose, it's a good opportunity to inspect the surrounding hoses — particularly the \u003ca href=\"\/products\/11167580553252\"\u003e32-864552\u003c\/a\u003e and \u003ca href=\"\/products\/11167580389412\"\u003e864539\u003c\/a\u003e — since access is much easier with the assembly partially disassembled.\u003c\/p\u003e","brand":"MERC","offers":[{"title":"Default Title","offer_id":51324691087396,"sku":"864509","price":95.24,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0743\/5799\/7604\/files\/images_11.png?v=1788205578","url":"https:\/\/marisolmarine.com\/products\/merc-368","provider":"Marisol Marine Company","version":"1.0","type":"link"}