{"title":"MerCruiser 4-Stroke 120-260HP Marine Engine Parts","description":"\u003csection id=\"hero\" style=\"padding:16px 0;\"\u003e\n  \u003cp\u003eThis page covers MerCruiser 4‑Stroke 120–260HP sterndrive engines. Use it to find compatible parts and service information, including maintenance tips, frequently replaced items, and troubleshooting guidance. You can also browse the main MerCruiser 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\/section.\u003c\/p\u003e\n  \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser\" style=\"display:inline-block;padding:10px 16px;border:1px solid #0a4;border-radius:6px;text-decoration:none;\"\u003eBrowse All MerCruiser Parts\u003c\/a\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"identify-model\"\u003e\n  \u003ch2\u003eHow to Identify Your 120–260HP Model\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eEngine serial number: Look for a tag or decal on the starboard side of the engine block or on the flame arrestor\/rocker cover. Record the full serial to confirm exact-fit parts.\u003c\/li\u003e\n    \u003cli\u003eTransom assembly and drive unit serials: Alpha One Gen II vs. Bravo drives use different water pumps, anodes, and seals. The drive serial is typically on the upper driveshaft housing.\u003c\/li\u003e\n    \u003cli\u003eFuel\/induction type: Note whether the engine is carbureted\/TKS, EFI, or MPI. Some ignition, fuel, and sensor parts differ by system.\u003c\/li\u003e\n    \u003cli\u003ePlatform cues: Inline‑4 (3.0L), V6 (4.3L), and V8 (5.0\/5.7L) use different ignition components, belts, and exhaust pieces; raw‑water vs. closed‑cooling also affects pump and hose selections.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"engine-overview\"\u003e\n  \u003ch2\u003eEngine \/ Platform Overview\u003c\/h2\u003e\n  \u003ch3\u003eInline‑4 Platform (Approx. 120–140HP)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;max-width:960px;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003e3.0L inline‑4 gasoline 4‑stroke; commonly carbureted\/TKS\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e3.0L (e.g., 120–135HP) paired primarily with Alpha drives\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eSimpler layout, good fuel economy, easy access for service\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eAlpha One Gen II uses a water pump in the drive; impeller and anodes differ from Bravo setups\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003eV6 Platform (Approx. 175–220HP)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;max-width:960px;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003e4.3L V6 gasoline 4‑stroke; carbureted, EFI, or MPI variants\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e4.3L (175–220HP) with Alpha or Bravo drives\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eStrong mid‑range torque, good all‑around performance\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eImpeller location depends on drive: Alpha = in drive; Bravo = engine‑mounted seawater pump\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003eV8 Platform (Approx. 220–260HP)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;max-width:960px;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003e5.0L\/5.7L V8 gasoline 4‑stroke; carb, TBI, or MPI\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e5.0\/5.7L (220–260HP) with Alpha or Bravo drives\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eHigher top‑end power and strong holeshot for heavier hulls\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eClosed‑cooling packages add heat‑exchanger components; verify pump, hose, and anode styles by serial\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\"\u003e\n  \u003ch2\u003eRoutine Maintenance \u0026amp; Service Parts\u003c\/h2\u003e\n  \u003cp\u003eIntervals below are general guidelines for typical recreational use. Always confirm procedures and specifications with your official MerCruiser service manual.\u003c\/p\u003e\n  \u003ctable style=\"width:100%;max-width:1000px;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eItem\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eInterval*\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eRemarks\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eParts Link\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eEngine oil + filter\u003c\/td\u003e\n        \u003ctd\u003eEvery 100 hours or annually\u003c\/td\u003e\n        \u003ctd\u003eWarm engine before draining; use marine‑rated oil and correct capacity\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-oil-filters\"\u003eMerCruiser Oil Filters\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSterndrive gear oil\u003c\/td\u003e\n        \u003ctd\u003eEvery 100 hours or annually\u003c\/td\u003e\n        \u003ctd\u003eInspect for water intrusion (milky oil); pressure‑test if leaks are suspected\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/lower-unit-seal-kits\"\u003eLower Unit Seal Kits\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSpark plugs\u003c\/td\u003e\n        \u003ctd\u003eEvery 100 hours or annually\u003c\/td\u003e\n        \u003ctd\u003eVerify correct heat range and gap; replace fouled or worn plugs\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/spark-plug\"\u003eSpark plug\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eFuel filter \/ water separator\u003c\/td\u003e\n        \u003ctd\u003e50–100 hours or each season\u003c\/td\u003e\n        \u003ctd\u003eDrain or replace sooner if water or debris is present\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-fuel-filters\"\u003eMerCruiser Fuel Filters\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eWater pump impeller \/ kit\u003c\/td\u003e\n        \u003ctd\u003eEvery 2 seasons or 200 hours\u003c\/td\u003e\n        \u003ctd\u003eAlpha: pump in drive; Bravo: engine‑mounted seawater pump; inspect wear plates and housings\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-impellers\"\u003eMerCruiser Impellers\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAnodes (zinc\/aluminum\/magnesium)\u003c\/td\u003e\n        \u003ctd\u003eInspect every 30–60 days; replace at ~50% loss\u003c\/td\u003e\n        \u003ctd\u003eMatch alloy to water type (salt, brackish, or fresh)\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-anodes\"\u003eMerCruiser Anodes\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSerpentine\/alternator belt\u003c\/td\u003e\n        \u003ctd\u003eInspect at 100 hours; replace as needed\u003c\/td\u003e\n        \u003ctd\u003eCheck for glazing, cracks, and proper tensioner operation\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/belt\"\u003eBelt\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eBellows (u‑joint, exhaust, shift)\u003c\/td\u003e\n        \u003ctd\u003eInspect annually; replace every 2–3 years\u003c\/td\u003e\n        \u003ctd\u003eCracked or stiff bellows risk water intrusion and driveline damage\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/bellow\"\u003eBellow\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\"\u003e\n  \u003ch2\u003eFrequently Used Parts Categories\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eRoutine Service: \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-service-maintenance-kits\"\u003eMerCruiser Service \u0026amp; Maintenance Kits\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eCooling System: \u003ca href=\"https:\/\/seasierra.com\/collections\/water-pumps\"\u003eWater pumps\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eFuel System: \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-fuel-filters\"\u003eMerCruiser Fuel Filters\u003c\/a\u003e and \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-fuel-pumps\"\u003eMerCruiser Fuel Pumps\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eIgnition \/ Electrical: \u003ca href=\"https:\/\/seasierra.com\/collections\/starters\"\u003eStarters\u003c\/a\u003e and \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-alternators\"\u003eMerCruiser Alternators\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003ePropulsion: \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-propellers\"\u003eMerCruiser Propellers\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eCorrosion Protection: \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-anodes\"\u003eMerCruiser Anodes\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eGaskets \u0026amp; Sealing: \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-gaskets\"\u003eMerCruiser Gaskets\u003c\/a\u003e\n\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"troubleshooting\"\u003e\n  \u003ch2\u003eCommon Symptoms \u0026amp; Quick Checks\u003c\/h2\u003e\n  \u003ctable style=\"width:100%;max-width:1000px;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eSymptom\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eCheck First\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ccc;\"\u003eRelated Parts\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eOverheating or high‑temp alarm at cruise\u003c\/td\u003e\n        \u003ctd\u003eDebris on water inlets, worn impeller, stuck thermostat, restricted hoses\/heat exchanger\u003c\/td\u003e\n        \u003ctd\u003eWater pump impeller kit, thermostat, intake screens, anodes, raw‑water hoses\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003ePoor acceleration or power loss under load\u003c\/td\u003e\n        \u003ctd\u003eDamaged\/fouled prop, clogged fuel filter, stale fuel, ignition misfire\u003c\/td\u003e\n        \u003ctd\u003ePropeller, fuel filter\/water separator, spark plugs, fuel pump\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eHard starting \/ rough idle\u003c\/td\u003e\n        \u003ctd\u003eBattery condition and grounds, contaminated fuel, carb\/TKS settings or EFI\/MPI IAC operation, vacuum leaks\u003c\/td\u003e\n        \u003ctd\u003eSpark plugs, fuel filter, air\/flame arrestor service parts, sensors\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eGearcase noise or metal in gear oil\u003c\/td\u003e\n        \u003ctd\u003eLow or milky gear lube, leaking seals, prop shaft fishing line, worn u‑joints\u003c\/td\u003e\n        \u003ctd\u003eLower unit seal kit, bearings, carrier o‑rings, gear lube\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"faq\"\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\u003eSome service items cross between years, but many parts vary by engine serial and drive family (Alpha vs. Bravo), as well as fuel system (carb\/EFI\/MPI) and cooling type. Always verify by serial number before ordering.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhen should the impeller be replaced?\u003c\/summary\u003e\n    \u003cp\u003eAs a rule of thumb, replace every two seasons or ~200 hours, and sooner if you operate in sandy or silty water. Inspect housings and wear plates and replace if scored.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow often should sterndrive gear oil be changed?\u003c\/summary\u003e\n    \u003cp\u003eChange at least annually or every 100 hours. If you find milky oil or metal, pressure‑test the drive and address seals or bearings before further use.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat information helps confirm part compatibility?\u003c\/summary\u003e\n    \u003cp\u003eProvide engine serial number, drive serial number, horsepower, fuel\/induction type (carb, EFI, or MPI), drive family (Alpha or Bravo), and whether the boat has raw‑water or closed‑cooling.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"cta\" style=\"padding:16px 0;\"\u003e\n  \u003cp\u003eReady to find parts by horsepower, year, and model? Browse the main MerCruiser collection to locate the exact components for your 120–260HP engine.\u003c\/p\u003e\n  \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser\" style=\"display:inline-block;padding:10px 16px;border:1px solid #0a4;border-radius:6px;text-decoration:none;\"\u003eShop MerCruiser Parts\u003c\/a\u003e\n  \u003cp style=\"margin-top:8px;color:#555;\"\u003eIf you’re unsure about your model, send us a photo of the serial\/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\/mercruiser-4-stroke-120-260hp-marine-engine-parts.oembed","provider":"SeaSierra","version":"1.0","type":"link"}