{"title":"Mercury 325HP 4-Stroke Outboard Engine Parts","description":"\u003csection id=\"hero\" style=\"padding:16px; max-width:1000px;\"\u003e\n  \u003cp\u003eThis page focuses on Mercury 4-Stroke 325HP outboard engines and helps you find compatible parts and service information. Below you’ll find maintenance tips, commonly replaced parts, and troubleshooting guidance. You can also browse the main Mercury collection. Scroll to the bottom of this page to start browsing parts for this engine. On the collection page, use the Filter \u0026amp; Sort controls 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 14px; background:#0a4; 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=\"padding:16px; max-width:1000px;\"\u003e\n  \u003ch2\u003eHow to Identify Your 325HP Model\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eLocate the serial number plate on the transom bracket or swivel bracket. Record the full serial\/number string and any model suffixes.\u003c\/li\u003e\n    \u003cli\u003eDecode the model tag: suffixes may indicate shaft length, control type (mechanical vs DTS), and market\/year. This is essential for selecting correct gearcase and cooling parts.\u003c\/li\u003e\n    \u003cli\u003eConfirm platform: many high-output Mercury 4-strokes are either supercharged inline‑6 (Verado L6) or later large-frame V8\/V10 platforms. Cowling shape, steering\/power steering modules, and intake layout help distinguish them.\u003c\/li\u003e\n    \u003cli\u003eNote rigging: Digital Throttle \u0026amp; Shift (DTS) vs mechanical controls, and power steering presence, can affect certain service and rigging components.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"platforms\" style=\"padding:16px; max-width:1000px;\"\u003e\n  \u003ch2\u003ePlatform Overview\u003c\/h2\u003e\n\n  \u003ch3\u003eSupercharged Inline‑6 Verado (L6)\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 #ccc; padding:8px; width:30%;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #ccc; 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;\"\u003eSupercharged inline‑6 EFI 4‑stroke with integrated electro‑hydraulic steering on many models.\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;\"\u003eOften aligned with Verado L6 high‑output ranges (e.g., 300–350 HP). Some service parts may overlap across adjacent HP ratings; always match by serial number.\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 mid‑range torque, smooth operation, and refined NVH characteristics.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eNotes\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eGearcase options (standard vs heavy‑duty), thermostat spec, and anode sets can vary. Verify cooling and gearcase parts by serial prefix and gear housing size.\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003eLarge‑Frame V8\/V10 4‑Stroke (Verado \/ Pro XS Families)\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 #ccc; padding:8px; width:30%;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #ccc; 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;\"\u003eNaturally aspirated, large‑displacement EFI 4‑stroke (V8 or V10, platform dependent) with advanced charging and digital controls on many variants.\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;\"\u003eHigh‑output 4‑stroke families in the 300–400 HP range. A 325 HP calibration may share many service items with adjacent outputs; confirm by serial.\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;\"\u003eBroad torque curve, robust charging for electronics, and strong mid‑to‑top‑end performance.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eNotes\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eWater pump kits, anodes, and gearcase seals may differ by gearcase diameter and shaft length. DTS vs mechanical control components are not interchangeable.\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"service-kits\" style=\"padding:16px; max-width:1000px;\"\u003e\n  \u003ch2\u003eRoutine Maintenance \u0026amp; Service Parts\u003c\/h2\u003e\n  \u003cp\u003eService intervals below are general guidelines for high‑horsepower Mercury 4‑stroke outboards. Always follow the official service manual for your exact serial number and operating conditions.\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 #ccc; padding:8px;\"\u003eItem\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #ccc; padding:8px;\"\u003eInterval*\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #ccc; padding:8px;\"\u003eRemarks\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #ccc; 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 FC‑W oil grade specified in your manual; replace filter and drain plug seals at each oil change.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px; border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/oil-filters\"\u003eShop Oil 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\u003c\/td\u003e\n        \u003ctd style=\"padding:8px; border-bottom:1px solid #eee;\"\u003eInspect magnet for metal, replace drain screw gaskets, and pressure\/vac test if water is present.\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\"\u003eLower 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;\"\u003e300 hours or 3 years\u003c\/td\u003e\n        \u003ctd style=\"padding:8px; border-bottom:1px solid #eee;\"\u003eCheck gap and heat range per platform; boosted engines can be sensitive to plug condition.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px; border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/spark-plug\"\u003eShop Spark 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 separator\u003c\/td\u003e\n        \u003ctd style=\"padding:8px; border-bottom:1px solid #eee;\"\u003e100 hours or each season\u003c\/td\u003e\n        \u003ctd style=\"padding:8px; border-bottom:1px solid #eee;\"\u003eReplace engine‑mounted and boat‑mounted filters; monitor for water and debris.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px; border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/fuel-filters-1\"\u003eShop Fuel 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;\"\u003e200 hours or 2 seasons (sooner in sandy\/silty water)\u003c\/td\u003e\n        \u003ctd style=\"padding:8px; border-bottom:1px solid #eee;\"\u003eReplace if tell‑tale weak, temps elevated, or after an overheat\/over‑rev in shallow water.\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 Kits\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eAnodes (internal \u0026amp; external)\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eInspect every 50 hours; replace at ~50% wear\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eMatch anode alloy to your water (zinc–salt, aluminum–brackish, magnesium–fresh) and keep electrical bonding intact.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/anodes\"\u003eShop Anodes\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n  \u003cp style=\"font-size:12px; color:#555;\"\u003e*Intervals are typical for recreational duty. Severe use (commercial, trolling, high hours, sandy water) may require shorter intervals.\u003c\/p\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"common-parts\" style=\"padding:16px; max-width:1000px;\"\u003e\n  \u003ch2\u003eFrequently Used Parts Categories\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eRoutine Service: \u003ca href=\"https:\/\/seasierra.com\/collections\/service-maintenance-kits\"\u003eService \u0026amp; Maintenance Kits\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\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\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\/electrical-items\"\u003eElectrical Items\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003ePropulsion: \u003ca href=\"https:\/\/seasierra.com\/collections\/propellers\"\u003ePropellers\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=\"padding:16px; max-width:1000px;\"\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 #ccc; padding:8px;\"\u003eSymptom\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #ccc; padding:8px;\"\u003eCheck First\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #ccc; 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 tell‑tale or overheat alarm\u003c\/td\u003e\n        \u003ctd style=\"padding:8px; border-bottom:1px solid #eee;\"\u003eInspect intake screens for debris, verify impeller condition, and test thermostats; confirm proper anode condition.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px; border-bottom:1px solid #eee;\"\u003eWater pump kit, thermostat(s), intake screen, anodes\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;\"\u003eCharge\/test battery, check spark plugs, confirm clean fuel and replace filters; inspect for air leaks on fuel lines.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px; border-bottom:1px solid #eee;\"\u003eSpark plugs, inline fuel filter, water‑separating filter\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;\"\u003eInspect propeller for damage or wrong pitch, check for fuel restriction, verify plug and coil condition.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px; border-bottom:1px solid #eee;\"\u003ePropeller\/hub, fuel filter, fuel pump, spark plugs\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eGearcase noise or metal in gear oil\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eCheck oil level\/condition, look for water intrusion, inspect propshaft seals for fishing line, and perform pressure\/vac test.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eDrain plug seals, lower unit seal kit, bearings\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=\"padding:16px; max-width:1000px;\"\u003e\n  \u003ch2\u003eFAQs\u003c\/h2\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eAre parts interchangeable across different years or platforms?\u003c\/summary\u003e\n    \u003cp\u003eSome service items overlap across adjacent horsepower ratings and years, but many components differ by serial prefix, gearcase type, control system (DTS vs mechanical), and platform (L6 vs V8\/V10). Always match parts to your exact serial number.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhen should the water pump impeller be replaced?\u003c\/summary\u003e\n    \u003cp\u003eCommon practice is every 200 hours or two seasons, and sooner for sandy\/silty use. Replace immediately after any overheat event or if the tell‑tale stream weakens.\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\u003eAt least every 100 hours or annually. If you detect water, metal debris, or burned odor, service the gearcase sooner and consider a seal kit with pressure\/vacuum testing.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat information do I need to confirm part compatibility?\u003c\/summary\u003e\n    \u003cp\u003eProvide the engine serial number, model name, horsepower, shaft length, control type (DTS or mechanical), gearcase size, and country\/market. Photos of the nameplate and the part needed are also helpful.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"cta\" style=\"padding:16px; max-width:1000px;\"\u003e\n  \u003cp\u003eReady to find the parts you need? Browse the Mercury collection by horsepower, year, and model to narrow down compatible components for your engine.\u003c\/p\u003e\n  \u003ca href=\"https:\/\/seasierra.com\/collections\/mercury-outboard-parts\" style=\"display:inline-block; padding:10px 14px; background:#0a4; color:#fff; text-decoration:none; border-radius:4px;\"\u003eBrowse All Mercury 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 — we’ll help verify compatibility.\u003c\/p\u003e\n\u003c\/section\u003e","products":[],"url":"https:\/\/seasierra.com\/collections\/mercury-325hp-4-stroke-outboard-engine-parts.oembed","provider":"SeaSierra","version":"1.0","type":"link"}