{"product_id":"677-45113-a0-power-head-base-gasket-for-yamaha-mariner-6b-8b-jlm-marine","title":"677-45113-A0 Power Head Base Gasket for Yamaha Mariner 6B 8B | JLM Marine","description":"\u003ch2\u003ePower Head Base Gasket – Fits Yamaha Mariner 6B 8B 2-Stroke Outboards\u003c\/h2\u003e\n\n\u003cp\u003eThis aftermarket powerhead base gasket is precision-engineered for Yamaha Mariner 6 HP and 8 HP 2-stroke outboard models (6B, 8B). Designed specifically for units with serial numbers starting with \u003cstrong\u003e677\u003c\/strong\u003e, this gasket ensures a reliable seal between the powerhead and block, critical for maintaining compression and preventing oil\/fuel leaks.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eDirect replacement for OEM part numbers:\u003c\/strong\u003e 677-45113-A0, 677-45113-A1. Compatible with older Japan-manufactured Mariner models under the Yamaha platform.\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003eIncludes one complete powerhead base gasket\u003c\/li\u003e\n  \u003cli\u003eDesigned for 2-stroke 6 HP and 8 HP Yamaha Mariner outboards\u003c\/li\u003e\n  \u003cli\u003eFits only older Mariner Japan models with serial numbers starting with 677\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      \u003cth\u003eNotes\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eYamaha\u003c\/td\u003e\n      \u003ctd\u003e677-45113-A0\u003c\/td\u003e\n      \u003ctd\u003ePrimary OEM number\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eYamaha\u003c\/td\u003e\n      \u003ctd\u003e677-45113-A1\u003c\/td\u003e\n      \u003ctd\u003eSuperseded equivalent\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 Yamaha owners, here's a guide to help you identify your engine's serial\/model: \u003ca href=\"https:\/\/jlmmarine.com\/blogs\/serial-number-guide\/yamaha-outboard-serial-number-guide-2025\" rel=\"nofollow noopener\" target=\"_blank\"\u003eYamaha Serial Number Guide\u003c\/a\u003e. You can also review exploded diagrams to verify part numbers: \u003ca href=\"https:\/\/jlmmarine.com\/blogs\/serial-number-guide\/yamaha-outboard-parts-diagrams-catalog\" rel=\"nofollow noopener\" target=\"_blank\"\u003eYamaha Parts Diagrams \u0026amp; Catalog\u003c\/a\u003e.\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\u003eModel\u003c\/th\u003e\n      \u003cth\u003eRated HP\u003c\/th\u003e\n      \u003cth\u003eStroke\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\u003eYamaha Mariner\u003c\/td\u003e\n      \u003ctd\u003e6B\u003c\/td\u003e\n      \u003ctd\u003e6 HP\u003c\/td\u003e\n      \u003ctd\u003e2-Stroke\u003c\/td\u003e\n      \u003ctd\u003eSerial numbers starting with 677 (Old Japan models only)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eYamaha Mariner\u003c\/td\u003e\n      \u003ctd\u003e8B\u003c\/td\u003e\n      \u003ctd\u003e8 HP\u003c\/td\u003e\n      \u003ctd\u003e2-Stroke\u003c\/td\u003e\n      \u003ctd\u003eSerial numbers starting with 677 (Old Japan models only)\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\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\u003ePart Type\u003c\/td\u003e\n      \u003ctd\u003ePowerhead Base Gasket\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eApplication\u003c\/td\u003e\n      \u003ctd\u003eYamaha Mariner 6 HP \u0026amp; 8 HP 2-Stroke Outboards\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eCompatible Models\u003c\/td\u003e\n      \u003ctd\u003e6B, 8B\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eSerial Number Range\u003c\/td\u003e\n      \u003ctd\u003eStarting with 677\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eOEM Part Number\u003c\/td\u003e\n      \u003ctd\u003e677-45113-A0, 677-45113-A1\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eQuantity\u003c\/td\u003e\n      \u003ctd\u003e1 Gasket\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\u003eYour package includes:\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003e\u003cspan style=\"color:red;\"\u003e\u003cstrong\u003e1 × Outboard Power Head Base Gasket\u003c\/strong\u003e\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Guide\u003c\/h2\u003e\n\n\u003col\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDisconnect the fuel line and remove the spark plug wire\u003c\/strong\u003e to prevent accidental starting during service.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRemove the powerhead mounting bolts\u003c\/strong\u003e and carefully lift the powerhead assembly off the engine block.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eThoroughly clean all mating surfaces\u003c\/strong\u003e on both the powerhead and the block, removing all old gasket material and residue. Use a gasket scraper and solvent; ensure surfaces are dry before proceeding.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eInspect both surfaces for warping, cracks, or damage.\u003c\/strong\u003e Address any irregularities before installing the new gasket.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePosition the new powerhead base gasket\u003c\/strong\u003e onto the engine block, aligning all bolt holes and ports precisely.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCarefully lower the powerhead\u003c\/strong\u003e back onto the gasket, ensuring it seats evenly without shifting the gasket.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eInstall all mounting bolts hand-tight first,\u003c\/strong\u003e then torque them to manufacturer specifications in a cross-pattern sequence to ensure even compression.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReconnect the spark plug wire and fuel line,\u003c\/strong\u003e then perform a visual inspection for proper alignment and seating.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eStart the engine and let it reach operating temperature.\u003c\/strong\u003e Check for oil or fuel leaks around the gasket perimeter; retorque bolts if necessary after the first run.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eHow do I confirm this gasket fits my Yamaha Mariner engine?\u003c\/strong\u003e\u003cbr\u003e\nVerify that your engine is a 6 HP or 8 HP 2-stroke model (6B or 8B) and that the serial number starts with \u003cstrong\u003e677\u003c\/strong\u003e. This gasket fits only older Japan-manufactured Mariner models; cross-check your existing OEM part number (677-45113-A0 or 677-45113-A1) to confirm compatibility.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat are the symptoms of a failing powerhead base gasket?\u003c\/strong\u003e\u003cbr\u003e\nCommon signs include oil or fuel seepage around the powerhead base, loss of compression, rough idle, or difficulty starting. If you notice wet residue or strong fuel odor near the powerhead-to-block joint, inspect and replace the gasket promptly.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eHow often should I replace the powerhead base gasket?\u003c\/strong\u003e\u003cbr\u003e\nReplace the gasket any time the powerhead is removed for service or repair. Gaskets are one-time-use components and should not be reused, as they compress and conform to mating surfaces during initial installation.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCan I reuse the old gasket if it looks intact?\u003c\/strong\u003e\u003cbr\u003e\nNo. Even if the old gasket appears undamaged, it has already compressed and conformed to the engine surfaces. Reusing it will likely result in leaks and poor sealing, compromising engine performance and reliability.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat is the difference between this aftermarket gasket and the OEM version?\u003c\/strong\u003e\u003cbr\u003e\nThis aftermarket gasket is manufactured to OEM specifications using comparable materials and production standards. It provides the same fit and sealing performance as the original Yamaha part, but at a more competitive price point.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eIs this an OEM part or aftermarket?\u003c\/strong\u003e\u003cbr\u003e\nThis 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\u003eHow fast do you ship and how much does it cost?\u003c\/strong\u003e\u003cbr\u003e\nWe 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\u003eWhat is your warranty and return policy?\u003c\/strong\u003e\u003cbr\u003e\nThis 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":51981000180025,"sku":"23GT283","price":23.3,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0885\/0433\/6697\/files\/12_b521b3fb-3ba2-4f8a-a02b-8ae514434e46.jpg?v=1772414146","url":"https:\/\/jlmmarine.com\/products\/677-45113-a0-power-head-base-gasket-for-yamaha-mariner-6b-8b-jlm-marine","provider":"JLM Marine Boat Parts Limited","version":"1.0","type":"link"}