{"product_id":"lower-unit-seal-kit-for-mercury-200-225-250-hp-efi-optimax-dfi-outboards-replaces-26-816575a4-sierra-18-8382","title":"Sierra 18-8382 Lower Unit Seal Kit - Replaces Mercury 26-816575A4 - Fits 200\/225\/250 HP EFI\/Optimax Outboards","description":"\u003cp\u003eThe Sierra 18-8382 Lower Unit Seal Kit is a gearcase seal kit for Mercury and Mariner outboard motors, designed to restore a watertight, oil-tight seal in the lower unit during a gearcase rebuild or seal replacement service. It is built as a direct equivalent to Mercury Marine part 26-816575A4, giving outboard owners and marine technicians a way to service the lower unit without sourcing the original Mercury part. Using the correct seal kit for the specific horsepower and serial number range is important, since Mercury outboards saw multiple lower unit casting and seal revisions across production, including the \"C-3 Casting\" variant covered by this kit.\u003c\/p\u003e\u003cp\u003eThis kit covers a range of Mercury 200 HP, 225 HP, and 250 HP outboards, including EFI and Optimax DFI configurations, matched to specific serial number breakpoints. Confirm your engine's horsepower, configuration (EFI or Optimax DFI), and serial number against the fitment list below before ordering, since lower unit seal kits are not interchangeable across all serial ranges.\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 18-8382\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCategory:\u003c\/strong\u003e Mercury Outboard Gearcase Seal Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.15 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Dimensions:\u003c\/strong\u003e 0.75 x 6 x 7.5 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282200428\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExterior Finish:\u003c\/strong\u003e Machined\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReplaces (OEM):\u003c\/strong\u003e 26-816575A4\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e200 HP (T801000 \u0026amp; Up)\u003c\/li\u003e\n\u003cli\u003e200 HP Optimax DFI (G438000 \u0026amp; Up)\u003c\/li\u003e\n\u003cli\u003e225 HP EFI (G438000 \u0026amp; Up)\u003c\/li\u003e\n\u003cli\u003e225 HP Optimax DFI (G590000-G960499)\u003c\/li\u003e\n\u003cli\u003e250 HP EFI (G438000 \u0026amp; Up)\u003c\/li\u003e\n\u003cli\u003eModels with C-3 Casting: 200 HP Optimax DFI (G386496-G437999)\u003c\/li\u003e\n\u003cli\u003eModels with C-3 Casting: 225 HP (D280813-G437999)\u003c\/li\u003e\n\u003cli\u003eModels with C-3 Casting: 225 HP EFI (G129222-G437999)\u003c\/li\u003e\n\u003cli\u003eModels with C-3 Casting: 250 HP EFI (G129222-G437999)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e26-816575A4\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-8382 Lower Unit Seal Kit fit?\u003c\/strong\u003e It fits Mercury\/Mariner 200 HP (T801000 \u0026amp; Up), 200 HP Optimax DFI (G438000 \u0026amp; Up), 225 HP EFI (G438000 \u0026amp; Up), 225 HP Optimax DFI (G590000-G960499), and 250 HP EFI (G438000 \u0026amp; Up) outboards, plus C-3 Casting models: 200 HP Optimax DFI (G386496-G437999), 225 HP (D280813-G437999), 225 HP EFI (G129222-G437999), and 250 HP EFI (G129222-G437999).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs Sierra 18-8382 the same as Mercury 26-816575A4?\u003c\/strong\u003e Yes, Sierra 18-8382 replaces Mercury Marine part number 26-816575A4 and is built to match its fit and function in the lower unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does this seal kit weigh?\u003c\/strong\u003e The Sierra 18-8382 Lower Unit Seal Kit weighs 0.15 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the dimensions of the 18-8382 seal kit packaging?\u003c\/strong\u003e The kit measures 0.75 x 6 x 7.5 inches as packaged.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill 18-8382 work on any Mercury 200 HP outboard?\u003c\/strong\u003e No, it is matched to specific serial number ranges. For a standard 200 HP it covers T801000 \u0026amp; Up, and for 200 HP Optimax DFI it covers G438000 \u0026amp; Up (or G386496-G437999 on C-3 Casting models), so the engine's serial number must be checked before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is C-3 Casting and why does it matter for this kit?\u003c\/strong\u003e C-3 Casting refers to a specific lower unit casting revision on certain Mercury 200-250 HP outboards; the Sierra 18-8382 kit lists separate serial number coverage for C-3 Casting models (for example 225 HP D280813-G437999) since those units use a different seal configuration than later castings.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-8382 kit cover 225 HP EFI and 225 HP Optimax DFI the same way?\u003c\/strong\u003e No, they have different serial number ranges: 225 HP EFI is covered at G438000 \u0026amp; Up (or G129222-G437999 on C-3 Casting models), while 225 HP Optimax DFI is covered at G590000-G960499.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat finish does the Sierra 18-8382 seal kit have?\u003c\/strong\u003e The components in the 18-8382 kit have a machined exterior finish.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this a genuine Mercury part or an aftermarket replacement?\u003c\/strong\u003e The Sierra 18-8382 is an aftermarket seal kit manufactured by Sierra as a replacement for Mercury Marine part 26-816575A4, not an OEM Mercury-branded part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat UPC is associated with the Sierra 18-8382 seal kit?\u003c\/strong\u003e The UPC for the Sierra 18-8382 Lower Unit Seal Kit is 808282200428.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988434432219,"sku":"SIE-18-8382","price":36.42,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-8382_lg__34267.1722518170.500.750.jpg?v=1785188607","url":"https:\/\/www.goodvibesmarina.com\/products\/lower-unit-seal-kit-for-mercury-200-225-250-hp-efi-optimax-dfi-outboards-replaces-26-816575a4-sierra-18-8382","provider":"Good Vibes Marina","version":"1.0","type":"link"}