{"title":"Mercury 4-Stroke Outboard Parts 50-125HP","description":"\u003csection id=\"hero\" style=\"max-width:900px;margin:0 auto;padding:16px 12px;\"\u003e\n  \u003cp\u003eThis page is tailored for Mercury 4‑Stroke 50–125HP outboard engines. Use it to find compatible parts and service information, including maintenance intervals, commonly replaced items, and troubleshooting guidance. You can also browse the main Mercury collection at any time. Scroll to the bottom of this page to start browsing parts for your engine, and remember you can use the Filter \u0026amp; Sort controls on the collection page to narrow results by horsepower, year range, and part category.\u003c\/p\u003e\n  \u003ca href=\"https:\/\/seasierra.com\/collections\/mercury-outboard-parts\" style=\"display:inline-block;padding:10px 16px;background:#1a73e8;color:#fff;text-decoration:none;border-radius:4px;\"\u003eBrowse All Mercury Parts\u003c\/a\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"identify-model\" style=\"max-width:900px;margin:0 auto;padding:16px 12px;\"\u003e\n  \u003ch2\u003eHow to Identify Your 50–125HP Model\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eLocate the serial plate: typically on the transom bracket or swivel bracket (port side) and embossed on an engine block tag. Record the full serial number.\u003c\/li\u003e\n    \u003cli\u003eModel details: note horsepower (50–125HP), four‑stroke EFI designation, shaft length (L\/XL), and whether your engine uses a standard gearcase or Command Thrust\/BigFoot.\u003c\/li\u003e\n    \u003cli\u003eYear\/serial breaks: Mercury parts often change at specific serial ranges. Always match parts by serial number, not just horsepower.\u003c\/li\u003e\n    \u003cli\u003eVisual cues: 50–60HP FourStroke models are commonly EFI with under‑cowl inline fuel filters; 75–115HP FourStroke models are inline‑4 EFI. Command Thrust\/BigFoot units have a larger gearcase and prop.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"engine-overview\" style=\"max-width:900px;margin:0 auto;padding:16px 12px;\"\u003e\n  \u003ch2\u003eEngine Platform Overview\u003c\/h2\u003e\n  \u003ch3\u003e50–60HP FourStroke EFI (Typical Platform)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;padding:8px;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;padding:8px;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eConfiguration\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eInline‑4 EFI 4‑Stroke (commonly 996cc class), standard or Command Thrust\/BigFoot gearcase\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eCommon Models\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e50 EFI FourStroke, 60 EFI FourStroke (standard and Command Thrust\/BigFoot)\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eAdvantages\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eExcellent fuel economy and mid‑range torque, smooth idle, broad prop options with Command Thrust\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eNotes\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eWater pump and gearcase parts can differ between standard and Command Thrust\/BigFoot. Fuel filter and thermostat styles can vary by serial number.\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003e75–115HP FourStroke EFI (Typical Platform)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;padding:8px;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;padding:8px;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eConfiguration\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eInline‑4 EFI 4‑Stroke, freshwater or saltwater use with sacrificial anodes\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eCommon Models\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e75 EFI, 90 EFI, 115 EFI FourStroke\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eAdvantages\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eStrong low‑end pull for heavier boats, reliable EFI starting, wide service parts availability\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eNotes\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eSpark plug type, fuel filter style, and anode shapes may change across serial ranges. Confirm by serial number and gearcase style.\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003cp style=\"margin-top:12px;color:#444;\"\u003eCompatibility note: “125HP” models may vary by market and year; some 125HP engines are legacy 2‑strokes and use different parts. For 125HP FourStroke coverage, verify the full serial number and gearcase type before ordering.\u003c\/p\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"service-kits\" style=\"max-width:900px;margin:0 auto;padding:16px 12px;\"\u003e\n  \u003ch2\u003eRoutine Maintenance \u0026amp; Service Parts\u003c\/h2\u003e\n  \u003cp\u003eIntervals below are typical guidelines for Mercury FourStroke outboards. Always follow your engine’s official service manual and adjust for heavy use, trolling, or sandy\/silty water.\u003c\/p\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;padding:8px;\"\u003eItem\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;padding:8px;\"\u003eInterval*\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;padding:8px;\"\u003eRemarks\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;padding:8px;\"\u003eParts Link\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eEngine oil + filter\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e100 hours or annually\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eUse marine 4‑stroke oil; replace filter each oil change; warm engine first for full drain\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/oil-filters\"\u003eOil Filters\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eGear oil (lower unit)\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e100 hours or annually; after any suspected water intrusion\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eInspect magnet for metal; milky oil indicates leaking seals—service before reuse\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/mercury-lower-unit-seal-kits\"\u003eMercury Lower Unit Seal Kits\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eSpark plugs\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eInspect 100 hours; replace ~300 hours or as needed\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eCheck gap and insulator color; replace if fouled, worn, or misfiring\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/spark-plug\"\u003eSpark Plugs\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eFuel filter \/ water‑separating filter\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e100 hours or annually\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eReplace under‑cowl inline\/cartridge filters; keep ethanol‑blended fuel fresh and stabilized\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/fuel-filters-1\"\u003eFuel Filters\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eWater pump impeller \/ kit\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e2 years or 200 hours (sooner in sandy\/silty water)\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eLoss of telltale or overheat alarms often indicate a worn impeller\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/mercury-water-pump-repair-kits\"\u003eMercury Water Pump Repair Kits\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eThermostat\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eInspect 2 years; replace if corroded\/sticking\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eStuck thermostats affect warm‑up and operating temp\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/mercury-outboard-parts\"\u003eMercury Outboard Parts\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eAnodes (zinc\/aluminum\/magnesium)\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eInspect 50 hours; replace when ~50% consumed\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eChoose material for your water type: salt (zinc), brackish (aluminum), fresh (magnesium)\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/anodes\"\u003eAnodes\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003ePropeller and hardware\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eInspect each outing\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eCheck for dings, hub slip, and fishing line at the prop shaft; verify tab washer and nut torque\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/propellers\"\u003ePropellers\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"common-parts\" style=\"max-width:900px;margin:0 auto;padding:16px 12px;\"\u003e\n  \u003ch2\u003eFrequently Used Parts Categories\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eRoutine Service: \u003ca href=\"https:\/\/seasierra.com\/collections\/oil-filters\"\u003eOil Filters\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eCooling System: \u003ca href=\"https:\/\/seasierra.com\/collections\/mercury-water-pump-repair-kits\"\u003eMercury Water Pump Repair Kits\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eFuel System: \u003ca href=\"https:\/\/seasierra.com\/collections\/fuel-filters-1\"\u003eFuel Filters\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eIgnition \/ Electrical: \u003ca href=\"https:\/\/seasierra.com\/collections\/spark-plug\"\u003eSpark Plugs\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eGearcase \u0026amp; Seals: \u003ca href=\"https:\/\/seasierra.com\/collections\/mercury-lower-unit-seal-kits\"\u003eMercury Lower Unit Seal Kits\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003ePropulsion: \u003ca href=\"https:\/\/seasierra.com\/collections\/propellers\"\u003ePropellers\u003c\/a\u003e and \u003ca href=\"https:\/\/seasierra.com\/collections\/propeller-guards\"\u003ePropeller Guards\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eCorrosion Protection: \u003ca href=\"https:\/\/seasierra.com\/collections\/anodes\"\u003eAnodes\u003c\/a\u003e\n\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"troubleshooting\" style=\"max-width:900px;margin:0 auto;padding:16px 12px;\"\u003e\n  \u003ch2\u003eCommon Symptoms \u0026amp; Quick Checks\u003c\/h2\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;padding:8px;\"\u003eSymptom\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;padding:8px;\"\u003eCheck First\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;padding:8px;\"\u003eRelated Parts\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eWeak telltale or overheat alarm\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eInspect intake screens for debris, verify thermostat function, and check impeller age\/condition\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eWater pump kit, thermostat, intake screen, anodes\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003ePoor acceleration or power loss\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eConfirm fresh fuel, replace\/inspect fuel filter, check prop condition and correct pitch, scan for fault codes if available\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eFuel filter, spark plugs, propeller, fuel injectors\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eHard starting or rough idle\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eVerify battery health and connections, prime fuel system, inspect for vacuum leaks at fuel lines\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eSpark plugs, fuel filter, fuel injectors, primer bulb\/lines\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eGearcase noise or metal on drain plug\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eCheck gear oil level\/condition; if milky or metallic, pressure test and service seals and bearings\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eLower unit seal kit, bearings, prop shaft seals\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"faq\" style=\"max-width:900px;margin:0 auto;padding:16px 12px;\"\u003e\n  \u003ch2\u003eFAQs\u003c\/h2\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eAre parts interchangeable between different years or platforms?\u003c\/summary\u003e\n    \u003cp\u003eNot always. Mercury uses serial number breaks that change filters, thermostats, water pump parts, and anodes. Gearcase style (standard vs Command Thrust\/BigFoot) also affects compatibility. Match parts to your full serial number.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhen should I replace the impeller?\u003c\/summary\u003e\n    \u003cp\u003eAs a rule, replace the water pump impeller every 2 years or ~200 hours—sooner if operating in sandy, silty, or shallow water, or if you notice a weak telltale or rising temperatures.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow often should I change lower unit gear oil?\u003c\/summary\u003e\n    \u003cp\u003eChange gear oil every 100 hours or annually, and any time the unit is submerged or water intrusion is suspected. Inspect the drain plug magnet for metal and address leaks before reuse.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat information do you need to confirm part compatibility?\u003c\/summary\u003e\n    \u003cp\u003eProvide the full engine serial number, horsepower, four‑stroke EFI designation, shaft length (L\/XL), and whether it is a standard or Command Thrust\/BigFoot gearcase. Photos of the nameplate and the part can also help.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"cta\" style=\"max-width:900px;margin:0 auto;padding:16px 12px;\"\u003e\n  \u003cp\u003eReady to find parts by horsepower, year, and model? Browse our main Mercury collection and use the Filter \u0026amp; Sort tools to quickly narrow results.\u003c\/p\u003e\n  \u003ca href=\"https:\/\/seasierra.com\/collections\/mercury-outboard-parts\" style=\"display:inline-block;padding:10px 16px;background:#1a73e8;color:#fff;text-decoration:none;border-radius:4px;\"\u003eShop Mercury Outboard Parts\u003c\/a\u003e\n  \u003cp style=\"margin-top:8px;color:#444;\"\u003eIf you’re unsure about your model, send us a clear photo of the nameplate and the part you need and we’ll help verify compatibility.\u003c\/p\u003e\n\u003c\/section\u003e","products":[{"product_id":"lower-unit-seal-kit-fits-mercury-mariner-30-125-hp-replaces-26-43035a4","title":"Mercury Mariner Lower Unit Gearcase Seal Kit, 30–125 HP 2- and 4-Stroke, 3- and 4-Cylinder","description":"\u003c!-- 🔧 Table Styles (include only once per page) --\u003e\n\u003cstyle\u003e\n  .ss-table-wrap { overflow-x:auto; -webkit-overflow-scrolling:touch; }\n  table.ss-table { width:100%; border-collapse:collapse; min-width:640px; }\n  table.ss-table th, table.ss-table td {\n    padding:10px 12px; border:1px solid #e5e7eb; text-align:left; vertical-align:top;\n  }\n  table.ss-table th {\n    white-space:nowrap;\n    word-break:normal;\n    letter-spacing:normal;\n    font-weight:600;\n    background:#f8fafc;\n  }\n  @media (max-width:480px){\n    table.ss-table th, table.ss-table td { padding:8px 10px; font-size:14px; }\n  }\n\u003c\/style\u003e\n\u003csection\u003e\n  \u003ch2\u003eProduct Details\u003c\/h2\u003e\n  \u003cp\u003eThis \u003cstrong\u003elower unit gearcase seal kit\u003c\/strong\u003e is intended for Mercury and Mariner outboards rated from \u003cstrong\u003e30 to 125 HP\u003c\/strong\u003e with either 2-stroke or 4-stroke powerheads and 3- or 4-cylinder configurations. It is designed for lower unit and gearcase service where worn or damaged seals, gaskets, O-rings, and related sealing components need to be replaced.\u003c\/p\u003e\n  \u003cp\u003eThe kit is listed as an aftermarket replacement for the Mercury reference numbers \u003cstrong\u003e26-43035A1\u003c\/strong\u003e, \u003cstrong\u003e26-43035A2\u003c\/strong\u003e, \u003cstrong\u003e26-43035A3\u003c\/strong\u003e, \u003cstrong\u003e26-43035A4\u003c\/strong\u003e, and \u003cstrong\u003e26-43035A05\u003c\/strong\u003e. Confirm the complete engine model and serial-number range before ordering because lower-unit components can vary by gearcase design, gear ratio, and serial break.\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eLower unit and gearcase seal kit for Mercury and Mariner outboards.\u003c\/li\u003e\n    \u003cli\u003eApplications covering 30–125 HP, 2-stroke and 4-stroke, 3- and 4-cylinder configurations.\u003c\/li\u003e\n    \u003cli\u003eSupports gearcase resealing during lower-unit repair or maintenance.\u003c\/li\u003e\n    \u003cli\u003eAftermarket replacement; not manufactured or branded by Mercury Marine.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n  \u003ch2\u003ePart Number Matrix\u003c\/h2\u003e\n  \u003cp\u003eThese references are provided for identification and cross-reference purposes. They do not replace verification against the exact engine model and serial number.\u003c\/p\u003e\n  \u003cdiv class=\"ss-table-wrap\"\u003e\n    \u003ctable class=\"ss-table\" aria-label=\"Part Number Matrix\"\u003e\n      \u003cthead\u003e\n        \u003ctr\u003e\n          \u003cth\u003eBrand or Reference\u003c\/th\u003e\n          \u003cth\u003ePart Number\u003c\/th\u003e\n          \u003cth\u003eReference Type\u003c\/th\u003e\n        \u003c\/tr\u003e\n      \u003c\/thead\u003e\n      \u003ctbody\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eMercury\u003c\/td\u003e\n          \u003ctd\u003e26-43035A1\u003c\/td\u003e\n          \u003ctd\u003eManufacturer reference\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eMercury\u003c\/td\u003e\n          \u003ctd\u003e26-43035A2\u003c\/td\u003e\n          \u003ctd\u003eManufacturer reference\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eMercury\u003c\/td\u003e\n          \u003ctd\u003e26-43035A3\u003c\/td\u003e\n          \u003ctd\u003eManufacturer reference\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eMercury\u003c\/td\u003e\n          \u003ctd\u003e26-43035A4\u003c\/td\u003e\n          \u003ctd\u003eManufacturer reference\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eMercury\u003c\/td\u003e\n          \u003ctd\u003e26-43035A05\u003c\/td\u003e\n          \u003ctd\u003eManufacturer reference\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eSierra\u003c\/td\u003e\n          \u003ctd\u003e18-2626\u003c\/td\u003e\n          \u003ctd\u003eAftermarket cross-reference\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eGLM\u003c\/td\u003e\n          \u003ctd\u003e87590\u003c\/td\u003e\n          \u003ctd\u003eAftermarket cross-reference\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eMallory\u003c\/td\u003e\n          \u003ctd\u003e9-74200\u003c\/td\u003e\n          \u003ctd\u003eAftermarket cross-reference\u003c\/td\u003e\n        \u003c\/tr\u003e\n      \u003c\/tbody\u003e\n    \u003c\/table\u003e\n  \u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n  \u003ch2\u003eEngine and Model Compatibility\u003c\/h2\u003e\n  \u003cp\u003eThe company fitment range for this product is Mercury and Mariner outboards rated \u003cstrong\u003e30–125 HP\u003c\/strong\u003e, covering both \u003cstrong\u003e2-stroke and 4-stroke\u003c\/strong\u003e engines with \u003cstrong\u003e3- or 4-cylinder\u003c\/strong\u003e configurations.\u003c\/p\u003e\n  \u003cp\u003eCatalog occurrences for the referenced gearcase seal application include selected Mercury 30 HP and 40 HP models, 4-stroke applications, Bigfoot gearcases, and gear housings with different serial-number breaks. These examples are not a complete fitment list. Always compare the engine model, horsepower, stroke, cylinder count, gearcase configuration, and serial number with the applicable service or parts catalog.\u003c\/p\u003e\n  \u003cdiv class=\"ss-table-wrap\"\u003e\n    \u003ctable class=\"ss-table\" aria-label=\"Mercury and Mariner Compatibility Summary\"\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\u003eCylinder Configuration\u003c\/th\u003e\n          \u003cth\u003eFitment Conditions\u003c\/th\u003e\n        \u003c\/tr\u003e\n      \u003c\/thead\u003e\n      \u003ctbody\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eMercury \/ Mariner\u003c\/td\u003e\n          \u003ctd\u003e30–125 HP\u003c\/td\u003e\n          \u003ctd\u003e2-stroke or 4-stroke\u003c\/td\u003e\n          \u003ctd\u003e3- or 4-cylinder\u003c\/td\u003e\n          \u003ctd\u003eVerify exact model, gearcase design, and serial-number range before purchase.\u003c\/td\u003e\n        \u003c\/tr\u003e\n      \u003c\/tbody\u003e\n    \u003c\/table\u003e\n  \u003c\/div\u003e\n  \u003cp\u003e\u003cstrong\u003eImportant:\u003c\/strong\u003e The horsepower range alone does not confirm fitment. Do not use this listing for a specific engine unless the applicable serial-number and gearcase conditions match.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n  \u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n  \u003cdl\u003e\n    \u003cdt\u003eProduct Type\u003c\/dt\u003e\n    \u003cdd\u003eLower unit and gearcase seal kit\u003c\/dd\u003e\n    \u003cdt\u003eCompatible Brands\u003c\/dt\u003e\n    \u003cdd\u003eMercury and Mariner\u003c\/dd\u003e\n    \u003cdt\u003eRated Horsepower Range\u003c\/dt\u003e\n    \u003cdd\u003e30–125 HP\u003c\/dd\u003e\n    \u003cdt\u003eEngine Stroke\u003c\/dt\u003e\n    \u003cdd\u003e2-stroke and 4-stroke applications\u003c\/dd\u003e\n    \u003cdt\u003eCylinder Configuration\u003c\/dt\u003e\n    \u003cdd\u003e3- and 4-cylinder applications\u003c\/dd\u003e\n    \u003cdt\u003eReplacement Type\u003c\/dt\u003e\n    \u003cdd\u003eAftermarket replacement\u003c\/dd\u003e\n  \u003c\/dl\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n  \u003ch2\u003eWhat’s in the Box\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eOne lower unit and gearcase seal kit.\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \u003cp\u003eIndividual seal, gasket, O-ring, and washer quantities can vary by application and kit configuration. Compare the kit contents with the parts diagram for your exact engine before installation.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n  \u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n  \u003col\u003e\n    \u003cli\u003eObtain the correct service manual for the exact outboard model and serial-number range.\u003c\/li\u003e\n    \u003cli\u003eDisconnect the battery and place the engine in neutral before beginning work.\u003c\/li\u003e\n    \u003cli\u003eDrain the gearcase lubricant through the designated drain and vent openings and inspect it for water contamination or metal debris.\u003c\/li\u003e\n    \u003cli\u003eRemove the propeller and lower unit according to the manufacturer’s service procedure.\u003c\/li\u003e\n    \u003cli\u003eDisassemble the gearcase only as necessary to access the seals and gaskets being replaced.\u003c\/li\u003e\n    \u003cli\u003eClean mating surfaces and seal bores thoroughly. Do not damage machined surfaces during seal removal.\u003c\/li\u003e\n    \u003cli\u003eInstall each replacement seal, gasket, O-ring, and washer in the correct location and orientation. Use the lubricant or sealant specified by the service manual.\u003c\/li\u003e\n    \u003cli\u003eReassemble the gearcase and reinstall the lower unit using the manufacturer’s torque specifications.\u003c\/li\u003e\n    \u003cli\u003eRefill the gearcase with the recommended marine gear lubricant using the correct fill procedure.\u003c\/li\u003e\n    \u003cli\u003ePressure- or vacuum-test the gearcase when the service procedure requires it, then check for leaks before returning the engine to service.\u003c\/li\u003e\n  \u003c\/ol\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n  \u003ch2\u003eTroubleshooting and FAQ\u003c\/h2\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow do I confirm this seal kit fits my outboard?\u003c\/summary\u003e\n    \u003cp\u003eConfirm that your engine is a Mercury or Mariner model in the 30–125 HP range with a 2-stroke or 4-stroke, 3- or 4-cylinder configuration. Then verify the exact model, gearcase design, and serial-number range against the applicable parts diagram. The reference numbers alone should not be used as the only fitment check.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat are common signs of lower-unit seal failure?\u003c\/summary\u003e\n    \u003cp\u003ePossible signs include milky or cloudy gear lubricant, water in the gearcase, lubricant leaking near the propeller shaft or driveshaft, or lubricant loss during operation. Inspect the gearcase before replacing parts because damage to shafts, bearing carriers, or sealing surfaces can also cause leaks.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eCan this kit be used for every Mercury or Mariner engine from 30 to 125 HP?\u003c\/summary\u003e\n    \u003cp\u003eNo. The stated horsepower range is a broad application range, not a guarantee for every model. Serial-number breaks, gearcase design, gear ratio, stroke, cylinder configuration, and regional model differences may affect fitment.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eIs this an OEM Mercury component?\u003c\/summary\u003e\n    \u003cp\u003eNo. This is an aftermarket replacement seal kit that references the listed Mercury manufacturer part numbers for identification and application matching.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eAre special tools required?\u003c\/summary\u003e\n    \u003cp\u003eDepending on the gearcase, installation may require seal drivers, bearing or carrier removal tools, a torque wrench, and a pressure\/vacuum tester. Use the service manual for the exact engine and gearcase before starting work.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat lubricant should be used after installation?\u003c\/summary\u003e\n    \u003cp\u003eUse the marine gear lubricant specified for your exact outboard by the engine manufacturer. Follow the service manual for lubricant grade, fill quantity, and filling sequence.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n  \u003ch2\u003eSafety and Important Information\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eVerify the full engine model, stroke, cylinder configuration, gearcase type, and serial number before ordering.\u003c\/li\u003e\n    \u003cli\u003eDo not rely on horsepower or a single reference number to confirm fitment.\u003c\/li\u003e\n    \u003cli\u003eCompare the original components and applicable parts diagram before disassembly.\u003c\/li\u003e\n    \u003cli\u003eFollow the manufacturer’s service procedures, torque specifications, sealant requirements, and lubricant specifications.\u003c\/li\u003e\n    \u003cli\u003eProfessional installation is recommended for gearcase disassembly, sealing, and pressure testing.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n  \u003ch2\u003eAbout Sea Sierra\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eMarine replacement parts selected for practical repair and maintenance applications.\u003c\/li\u003e\n    \u003cli\u003eClear cross-reference information to help identify the correct replacement component.\u003c\/li\u003e\n    \u003cli\u003eSupport focused on accurate application matching and dependable service-part sourcing.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":50723965993275,"sku":"23SK480","price":86.35,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/Lower_Unit_Gearcase_Seal_Kit_for_Mercury_Mariner_Outboard_30-125_HP_Motor__26-43035A4_-_JLM_MARINE-8287879.webp?v=1763038616"}],"url":"https:\/\/seasierra.com\/collections\/mercury-4-stroke-outboard-parts-50-125hp.oembed","provider":"SeaSierra","version":"1.0","type":"link"}