{"product_id":"5000309-gearcase-seal-kit-for-johnson-evinrude-jlm-marine","title":"5000309 Gearcase Seal Kit for Johnson Evinrude | JLM Marine","description":"\u003ch2\u003eGearcase Seal Kit for Johnson Evinrude Outboard Lower Units – OEM 5000309 \/ Sierra 18-8383\u003c\/h2\u003e\n\n\u003cp\u003eThis gearcase seal kit is designed for Johnson and Evinrude outboard lower units, covering a wide range of 2-stroke models from 40 HP to 75 HP with large housing configurations. Engineered to restore factory sealing performance, this kit ensures reliable protection against water intrusion and gear oil leakage in demanding marine environments.\u003c\/p\u003e\n\n\u003cp\u003eThis aftermarket replacement kit directly replaces \u003cstrong\u003eOMC Johnson\/Evinrude 5000309\u003c\/strong\u003e and \u003cstrong\u003eSierra Marine 18-8383\u003c\/strong\u003e, providing a cost-effective solution for lower unit maintenance and repair.\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003eComplete seal kit for lower unit gearcase applications\u003c\/li\u003e\n  \u003cli\u003eFits multiple Johnson\/Evinrude 2-stroke models from 1985–2009\u003c\/li\u003e\n  \u003cli\u003eDesigned for large housing lower units\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003ePart Number Cross-Reference\u003c\/h2\u003e\n\n\u003cp\u003eUse this table to confirm equivalent part numbers across OEM and aftermarket brands.\u003c\/p\u003e\n\n\u003ctable border=\"1\" cellpadding=\"8\" cellspacing=\"0\"\u003e\n  \u003cthead\u003e\n    \u003ctr\u003e\n      \u003cth\u003eBrand\u003c\/th\u003e\n      \u003cth\u003ePart Number\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eOMC Johnson\/Evinrude\u003c\/td\u003e\n      \u003ctd\u003e5000309\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eSierra Marine\u003c\/td\u003e\n      \u003ctd\u003e18-8383\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eCompatible Engine Models\u003c\/h2\u003e\n\n\u003cp\u003eConfirm your engine model\/year in the table below. For Johnson\/Evinrude owners, here's a guide to help you identify your engine's serial\/model: \u003ca href=\"https:\/\/jlmmarine.com\/blogs\/serial-number-guide\/johnson-serial-number-guide\" rel=\"nofollow noopener\" target=\"_blank\"\u003eJohnson\/Evinrude Serial Number Guide\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003cdiv style=\"overflow-x:auto;\"\u003e\n  \u003ctable border=\"1\" cellpadding=\"8\" cellspacing=\"0\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth\u003eBrand\u003c\/th\u003e\n        \u003cth\u003eRated HP\u003c\/th\u003e\n        \u003cth\u003eStroke\u003c\/th\u003e\n        \u003cth\u003eYears\u003c\/th\u003e\n        \u003cth\u003eNotes\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003e40 HP\u003c\/td\u003e\n        \u003ctd\u003e2 Stroke\u003c\/td\u003e\n        \u003ctd\u003e1997-2001, 2004-2009\u003c\/td\u003e\n        \u003ctd\u003eLarge Housing\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003e45 HP\u003c\/td\u003e\n        \u003ctd\u003e2 Stroke\u003c\/td\u003e\n        \u003ctd\u003e1997\u003c\/td\u003e\n        \u003ctd\u003eLarge Housing\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003e50 HP\u003c\/td\u003e\n        \u003ctd\u003e2 Stroke\u003c\/td\u003e\n        \u003ctd\u003e1995-1998, 2004-2009\u003c\/td\u003e\n        \u003ctd\u003eLarge Housing\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003e55 HP\u003c\/td\u003e\n        \u003ctd\u003e2 Stroke\u003c\/td\u003e\n        \u003ctd\u003e1997-2001, 2003-2005, 2008-2009\u003c\/td\u003e\n        \u003ctd\u003eLarge Housing\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003e60 HP\u003c\/td\u003e\n        \u003ctd\u003e2 Stroke\u003c\/td\u003e\n        \u003ctd\u003e1986-2001, 2004-2009\u003c\/td\u003e\n        \u003ctd\u003eLarge Housing\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003e65 HP\u003c\/td\u003e\n        \u003ctd\u003e2 Stroke\u003c\/td\u003e\n        \u003ctd\u003e1985-2001, 2008-2009\u003c\/td\u003e\n        \u003ctd\u003eLarge Housing\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003e70 HP\u003c\/td\u003e\n        \u003ctd\u003e2 Stroke\u003c\/td\u003e\n        \u003ctd\u003e1985-2001\u003c\/td\u003e\n        \u003ctd\u003eLarge Housing\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003e75 HP\u003c\/td\u003e\n        \u003ctd\u003e2 Stroke\u003c\/td\u003e\n        \u003ctd\u003e1985-1987\u003c\/td\u003e\n        \u003ctd\u003eLarge Housing\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\n\u003ctable border=\"1\" cellpadding=\"8\" cellspacing=\"0\"\u003e\n  \u003cthead\u003e\n    \u003ctr\u003e\n      \u003cth\u003eSpecification\u003c\/th\u003e\n      \u003cth\u003eValue\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eOEM Part Number\u003c\/td\u003e\n      \u003ctd\u003e5000309\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eAftermarket Part Number\u003c\/td\u003e\n      \u003ctd\u003e18-8383\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eApplication\u003c\/td\u003e\n      \u003ctd\u003eLower Unit Gearcase\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eHousing Type\u003c\/td\u003e\n      \u003ctd\u003eLarge Housing\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003ePackage Contents\u003c\/h2\u003e\n\n\u003cp\u003eThis kit includes \u003cspan style=\"color:red;\"\u003eall seals and components required for lower unit gearcase service\u003c\/span\u003e as shown in the product images:\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e1 × Seal Kit Lower Unit Gearcase\u003c\/strong\u003e (complete kit with all seals and components shown in images)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Guide\u003c\/h2\u003e\n\n\u003col\u003e\n  \u003cli\u003eDisconnect the spark plug wires to prevent accidental engine start. Drain all gear oil from the lower unit completely.\u003c\/li\u003e\n  \u003cli\u003eRemove the propeller, then unbolt and separate the lower unit from the mid-section following your service manual.\u003c\/li\u003e\n  \u003cli\u003eDisassemble the lower unit gearcase, taking care to mark component positions for reassembly. Remove the drive shaft and propeller shaft.\u003c\/li\u003e\n  \u003cli\u003eCarefully remove all old seals, o-rings, and gaskets from the gearcase housing using appropriate seal removal tools.\u003c\/li\u003e\n  \u003cli\u003eThoroughly clean all sealing surfaces, removing any residue, corrosion, or old gasket material. Inspect components for wear or damage.\u003c\/li\u003e\n  \u003cli\u003eInstall new seals from the kit using the proper seal driver tools to avoid damage. Apply marine-grade grease to seal lips as specified.\u003c\/li\u003e\n  \u003cli\u003eReinstall the propeller shaft and drive shaft, ensuring proper alignment and engagement of gears.\u003c\/li\u003e\n  \u003cli\u003eReassemble the gearcase components in reverse order of disassembly, referencing your markings.\u003c\/li\u003e\n  \u003cli\u003eReattach the lower unit to the mid-section, torquing all fasteners to manufacturer specifications.\u003c\/li\u003e\n  \u003cli\u003eRefill the lower unit with the correct type and quantity of gear oil through the fill port.\u003c\/li\u003e\n  \u003cli\u003eCheck for proper gear oil level at the vent hole. Reinstall the propeller and reconnect spark plug wires.\u003c\/li\u003e\n  \u003cli\u003ePerform a water test to verify proper sealing and operation, checking for leaks or abnormal noise.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: How do I confirm this seal kit fits my specific Johnson or Evinrude outboard?\u003c\/strong\u003e\u003cbr\u003e\nA: Verify your engine's horsepower, stroke type (2-stroke), year, and confirm it uses a large housing lower unit. Cross-reference your current OEM part number (5000309) or check the compatibility table above. If your model\/year matches and you have a large housing configuration, this kit will fit.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: What are the signs that my gearcase seals need replacement?\u003c\/strong\u003e\u003cbr\u003e\nA: Common symptoms include visible gear oil leaking from the lower unit, milky or contaminated gear oil (indicating water intrusion), difficulty shifting gears, or unusual noise from the lower unit. Regular inspection during oil changes is recommended.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: How often should I replace the lower unit seals?\u003c\/strong\u003e\u003cbr\u003e\nA: Replace seals whenever you perform major lower unit service, such as water pump replacement or gear repair. Preventive replacement every 3-5 years or if you notice oil contamination is good practice, especially for motors used in saltwater environments.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: Do I need any special tools to install this seal kit?\u003c\/strong\u003e\u003cbr\u003e\nA: Yes, proper seal installation requires seal driver tools of appropriate sizes, a torque wrench, and potentially a bearing puller. Marine-grade grease and the correct gear oil are also necessary. Consult your service manual for specific procedures and torque specifications.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: What's the difference between this aftermarket kit and the OEM version?\u003c\/strong\u003e\u003cbr\u003e\nA: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: How fast do you ship and how much does it cost?\u003c\/strong\u003e\u003cbr\u003e\nA: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: What is your warranty and return policy?\u003c\/strong\u003e\u003cbr\u003e\nA: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused \u0026amp; in original condition); please see our policy page or reach out for instructions.\u003c\/p\u003e\n\n\u003ch2\u003eImportant Notes\u003c\/h2\u003e\n\n\u003cul\u003e\n  \u003cli\u003eVerify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.\u003c\/li\u003e\n  \u003cli\u003eThis product is an aftermarket replacement part and is not an OEM component.\u003c\/li\u003e\n  \u003cli\u003eProfessional installation is recommended to ensure safety and optimal performance.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhy Choose JLM MARINE?\u003c\/h2\u003e\n\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eQuality Assured:\u003c\/strong\u003e As a trusted manufacturer for over 20 years, we supply top marine brands globally.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFast Global Shipping:\u003c\/strong\u003e Free delivery worldwide in 5–15 days.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDirect from Manufacturer:\u003c\/strong\u003e Competitive pricing without compromising quality.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"JLM Marine","offers":[{"title":"Default Title","offer_id":51981023019321,"sku":"24OSK708","price":57.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0885\/0433\/6697\/files\/f177d85e8c1e6745.jpg?v=1772414755","url":"https:\/\/jlmmarine.com\/products\/5000309-gearcase-seal-kit-for-johnson-evinrude-jlm-marine","provider":"JLM Marine Boat Parts Limited","version":"1.0","type":"link"}