{"product_id":"sierra-18-0595-oil-seal-for-mercury-outboard-powerhead-replaces-mercury-26-66303-1-125-in-od","title":"Sierra Oil Seal 18-0595, Replaces Mercury Marine 26-66303","description":"\u003cp\u003eThe Sierra 18-0595 is an oil seal engineered for Mercury outboard powerheads, providing a reliable barrier against oil leakage at the shaft. It is built with a 1.125 inch outer diameter and a 0.688 inch shaft size, sized to fit precisely into the powerhead seal bore it is designed for. At only 0.250 inches wide, it is a compact component intended to sit flush within its mounting location without interference from surrounding parts.\u003c\/p\u003e\u003cp\u003eThis seal directly replaces Mercury Marine part number 26-66303, making it a straightforward drop-in option for powerhead seal replacement and rebuild work. Sierra parts are constructed with quality materials aimed at delivering dependable service life and consistent sealing performance in the marine environment. The 18-0595 falls under Sierra's Mercury Outboard Powerhead Seals \u0026amp; O-Rings category, reflecting its specific application in outboard powerhead assemblies where maintaining oil containment is critical to engine protection.\u003c\/p\u003e\u003cp\u003eAt just 0.02 pounds, this is a small, lightweight part that is easy to keep on hand as a maintenance spare. Whether performing a full powerhead rebuild or addressing an isolated oil seal failure, the 18-0595 gives technicians and boat owners a Sierra-manufactured alternative to the OEM Mercury Marine part.\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 18-0595\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Name:\u003c\/strong\u003e Oil Seal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCategory:\u003c\/strong\u003e Mercury Outboard Powerhead Seals \u0026amp; O-Rings\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOuter Diameter:\u003c\/strong\u003e 1.125 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eShaft Size:\u003c\/strong\u003e 0.688 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWidth:\u003c\/strong\u003e 0.250 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.02 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282233983\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross-Reference:\u003c\/strong\u003e Mercury Marine 26-66303\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMercury outboard powerheads using Mercury Marine oil seal 26-66303\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e26-66303\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-0595 oil seal replace?\u003c\/strong\u003e The Sierra 18-0595 directly replaces Mercury Marine part number 26-66303, so it can be installed anywhere that Mercury Marine seal is called for.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the outer diameter of the 18-0595 oil seal?\u003c\/strong\u003e The outer diameter is 1.125 inches, which is the size of the seal's outer edge that seats into the powerhead bore.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat shaft size does this Sierra oil seal fit?\u003c\/strong\u003e It is sized for a 0.688 inch shaft, matching the shaft diameter it seals against on Mercury outboard powerheads.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow wide is the Sierra 18-0595 seal?\u003c\/strong\u003e 0.250 inches wide, a compact dimension intended to fit flush within its designated seal location.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-0595 oil seal weigh?\u003c\/strong\u003e It weighs 0.02 pounds, a very light single-component part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-0595?\u003c\/strong\u003e The UPC is 808282233983, which can be used to confirm you are ordering the correct oil seal.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-0595 an OEM part or an aftermarket replacement?\u003c\/strong\u003e It is a Sierra-manufactured replacement seal built to replace Mercury Marine 26-66303, not an OEM Mercury Marine part itself, though it is designed as a direct equivalent.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat application is the 18-0595 oil seal used on?\u003c\/strong\u003e It is listed under Mercury Outboard Powerhead Seals \u0026amp; O-Rings, indicating its use in Mercury outboard powerhead assemblies.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when you order the 18-0595?\u003c\/strong\u003e Each order includes one Sierra 18-0595 oil seal.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-0595 suitable for a powerhead rebuild?\u003c\/strong\u003e Yes, its role as a powerhead seal replacing Mercury Marine 26-66303 makes it applicable to powerhead rebuild and repair work.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988083945691,"sku":"SIE-18-0595","price":9.56,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-0595_lg__09089.1558118637.500.750.jpg?v=1785189109","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-0595-oil-seal-for-mercury-outboard-powerhead-replaces-mercury-26-66303-1-125-in-od","provider":"Good Vibes Marina","version":"1.0","type":"link"}