{"title":"Mercury 2-Stroke 25-35HP Outboard Marine Engine Parts","description":"\u003csection id=\"hero\" style=\"max-width:1000px;margin:0 auto;padding:16px 12px;\"\u003e\n  \u003cp\u003eThis page is built for Mercury 2‑Stroke 25–35HP outboard engines. Use it to find compatible parts and practical service information, including maintenance intervals, common replacement items, and troubleshooting tips. You can also browse the main Mercury collection. Scroll to the bottom of the page to start browsing parts for this engine, and on the collection page use the Filter \u0026amp; Sort controls to narrow 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;border:1px solid #222;border-radius:4px;text-decoration:none;\"\u003eBrowse All Mercury Parts\u003c\/a\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"identify-model\" style=\"max-width:1000px;margin:0 auto;padding:8px 12px;\"\u003e\n  \u003ch2\u003eHow to Identify Your 25–35HP Model\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eLocate the serial\/nameplate on the starboard transom clamp bracket or swivel bracket. Record the full serial number and any model suffix.\u003c\/li\u003e\n    \u003cli\u003eDecode the suffix details: shaft length (S\/L\/XL), starting method (manual vs. electric), and control type (tiller vs. remote). These affect ignition, harness, and bracket components.\u003c\/li\u003e\n    \u003cli\u003e2‑Stroke identification: most 25–35HP units are carbureted, inline‑2 designs. Some models use premix (typically 50:1), while others may have an external oiling system. Confirm which your engine has before ordering fuel\/oil components.\u003c\/li\u003e\n    \u003cli\u003eShared platforms: many 25\/30\/35HP variants share major castings but differ in carburetor jetting, timing, exhaust, and gear ratio. Use the serial number to verify exact fit.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"engine-overview\" style=\"max-width:1000px;margin:0 auto;padding:8px 12px;\"\u003e\n  \u003ch3\u003eInline‑2 Carbureted 2‑Stroke (typical for 25–35HP)\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:6px;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;padding:6px;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eConfiguration\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eInline‑2, carbureted 2‑Stroke with reed induction; manual or electric start; tiller or remote control.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eCommon Models\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eMercury 25\/30\/35HP 2‑Stroke (late 1980s–early 2000s typical). Some versions equipped with external oiling systems; others are premix.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eAdvantages\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eLight weight, simple service, strong low‑to‑mid torque, widely available service parts.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eNotes\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eMany parts interchange across 25–35HP, but verify by serial number, shaft length, and starting\/controls. Replace the water pump impeller regularly and monitor gear oil for water intrusion.\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=\"max-width:1000px;margin:0 auto;padding:8px 12px;\"\u003e\n  \u003ch2\u003eRoutine Maintenance \u0026amp; Service Parts\u003c\/h2\u003e\n  \u003cp\u003eIntervals below are general guidelines for typical use. Always follow the official service manual and local 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:6px;\"\u003eItem\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;padding:6px;\"\u003eInterval*\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;padding:6px;\"\u003eRemarks\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;padding:6px;\"\u003eParts Link\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eGear oil (lower unit)\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eEvery 100 hours or annually\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eInspect for water (milky oil). Replace sealing washers; reseal if water intrusion found.\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;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:6px;border-bottom:1px solid #eee;\"\u003eSpark plugs\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eInspect every 50 hours; replace at 100 hours\/season\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eCheck heat range and gap per manual; carry spares onboard.\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;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:6px;border-bottom:1px solid #eee;\"\u003eFuel filter (inline)\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eEvery 100 hours or annually\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eReplace sooner if poor fuel quality or storage issues are suspected.\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;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:6px;border-bottom:1px solid #eee;\"\u003eWater pump impeller \/ kit\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eImpeller: 1 year\/100 hours; Full kit: 2–3 seasons\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eEssential for cooling and tell‑tale flow; replace more often in sandy\/silty water.\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;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:6px;border-bottom:1px solid #eee;\"\u003eAnodes (corrosion protection)\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eInspect often; replace when ~50% consumed\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eMatch anode material to water type (salt, brackish, fresh).\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;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:6px;border-bottom:1px solid #eee;\"\u003e2‑Stroke oiling (premix or external oiling)\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eCheck each season\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eConfirm correct premix ratio or service external oil tank\/lines if equipped.\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;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:6px;border-bottom:1px solid #eee;\"\u003eThermostat (cooling system)\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eEvery 2 years or if over‑cooling\/overheating\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eStuck thermostats affect warm‑up and overall running temperature.\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;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    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"common-parts\" style=\"max-width:1000px;margin:0 auto;padding:8px 12px;\"\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 (impellers \u0026amp; pump kits): \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 (filters \u0026amp; pumps): \u003ca href=\"https:\/\/seasierra.com\/collections\/fuel-pumps\"\u003eFuel Pumps\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\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\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:1000px;margin:0 auto;padding:8px 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 #ccc;padding:6px;\"\u003eSymptom\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;padding:6px;\"\u003eCheck First\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;padding:6px;\"\u003eRelated Parts\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eWeak tell‑tale stream or overheat alarm\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eInspect intake screens for blockage; evaluate impeller condition; verify thermostat operation.\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eWater pump kit, intake screen, thermostat, outlet nozzle\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003ePoor acceleration or power loss\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eCheck prop for damage\/cavitation; replace fuel filter; confirm fresh fuel; clean\/rebuild carburetor.\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003ePropeller, fuel filter, fuel pump, carburetor repair kit, spark plugs\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eHard starting or rough idle\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eVerify choke\/enrichment function; prime fuel system; inspect plugs and idle mixture settings.\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eSpark plugs, fuel lines\/primer bulb, carburetor kit\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eExcessive smoke (2‑Stroke)\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eConfirm correct premix ratio; check for stuck choke; inspect oiling system (if equipped) for over‑delivery.\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eSpark plugs, choke components, oil lines\/tank parts\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eGearcase noise or metal in gear oil\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eDrain and inspect gear oil; check for water intrusion; pressure\/vacuum test and reseal if needed.\u003c\/td\u003e\n        \u003ctd style=\"padding:6px;border-bottom:1px solid #eee;\"\u003eLower unit seal kit, water pump base gaskets, drain\/fill sealing washers\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:1000px;margin:0 auto;padding:8px 12px;\"\u003e\n  \u003ch2\u003eFAQs\u003c\/h2\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eAre parts interchangeable across different years or between 25\/30\/35HP models?\u003c\/summary\u003e\n    \u003cp\u003eMany components are shared, but variations in carburetion, ignition, gear ratios, and brackets exist. Always verify by serial number, shaft length, and starting\/control configuration before ordering.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhen should I replace the impeller?\u003c\/summary\u003e\n    \u003cp\u003eAs preventive maintenance, replace the impeller every 1 season or ~100 hours. In sandy or silty water, inspect more often. A full pump kit (housing, wear plate, seals) every 2–3 seasons helps long‑term reliability.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow often should I change the lower unit gear oil?\u003c\/summary\u003e\n    \u003cp\u003eAt least once per season or every 100 hours. If the oil appears milky, reseal the gearcase before further operation to prevent damage.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat information helps confirm part compatibility?\u003c\/summary\u003e\n    \u003cp\u003eProvide the engine serial number, horsepower, shaft length (S\/L\/XL), starting type (manual\/electric), tiller or remote control, and country\/region if available. Photos of the nameplate and the part in question are also very helpful.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"cta\" style=\"max-width:1000px;margin:0 auto;padding:16px 12px;\"\u003e\n  \u003cp\u003eReady to find the parts you need? Browse the main Mercury collection and use horsepower, year, and model filters to quickly narrow results.\u003c\/p\u003e\n  \u003ca href=\"https:\/\/seasierra.com\/collections\/mercury-outboard-parts\" style=\"display:inline-block;padding:10px 16px;border:1px solid #222;border-radius:4px;text-decoration:none;\"\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 photo of the nameplate and the part you need and we’ll help verify compatibility.\u003c\/p\u003e\n\u003c\/section\u003e","products":[],"url":"https:\/\/seasierra.com\/collections\/mercury-2-stroke-25-35hp-outboard-marine-engine-parts.oembed","provider":"SeaSierra","version":"1.0","type":"link"}