{"title":"GM 250HP 4-Stroke Marine Engine Parts","description":"\u003csection id=\"hero\" style=\"padding:16px 0;\"\u003e\n  \u003cp\u003e\n    This page supports GM 250HP 4‑Stroke marine engines commonly found in sterndrive\/inboard packages (e.g., MerCruiser and similar marinized GM platforms). 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 this page to start browsing parts for this engine, and on the collection page use the “Filter \u0026amp; Sort” controls to narrow results by horsepower, year range, and part category.\n  \u003c\/p\u003e\n  \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser\" style=\"display:inline-block;padding:10px 14px;background:#0a5;border-radius:6px;color:#fff;text-decoration:none;\"\u003eBrowse All MerCruiser Parts\u003c\/a\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"identify-model\" style=\"padding:16px 0;\"\u003e\n  \u003ch2\u003eHow to Identify Your 250HP Model\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eFind the engine identification: look for a serial or product ID plate on the intake manifold area, starboard side of the block, or on\/near the flame arrestor; the sterndrive unit has a separate serial tag on the transom assembly.\u003c\/li\u003e\n    \u003cli\u003eDecode the model description: examples include MerCruiser 5.7L (250), Volvo Penta 5.7GL\/Gi, or OMC 250 King Cobra. Suffixes often indicate ignition system, fuel system (carb\/TBI\/EFI), and drive family (Alpha\/Bravo).\u003c\/li\u003e\n    \u003cli\u003eDistinguish platforms: GM small‑block V8 (5.7L\/350 CID) vs GM V6 (4.3L\/262 CID). Note carburetor vs EFI\/MPI, and whether the raw‑water pump is drive‑mounted (common on Alpha) or engine‑mounted (common on Bravo and some others).\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"engine-overview\" style=\"padding:16px 0;\"\u003e\n  \u003ch2\u003ePlatform Overview\u003c\/h2\u003e\n\n  \u003ch3\u003eGM 5.7L Small‑Block V8 (~250 HP)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;max-width:900px;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;\"\u003eGM small‑block V8, 5.7L (350 CID) 4‑stroke; carbureted, TBI, or early EFI variants depending on package\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;\"\u003eMerCruiser 5.7L 250\/260; OMC 250 King Cobra; Volvo Penta 5.7GL\/5.7Gi (early)\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‑to‑mid torque, wide parts availability, straightforward service procedures\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;\"\u003eImpeller location varies by drive family (Alpha: drive‑mounted; Bravo: often engine‑mounted pump). Ignition systems (e.g., Thunderbolt) and fuel delivery affect plug type and service parts.\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003eGM 4.3L V6 (common in this family)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;max-width:900px;border-collapse:collapse;margin-top:12px;\"\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;\"\u003eGM V6, 4.3L (262 CID) 4‑stroke; carb\/TBI\/MPI depending on year and package\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;\"\u003eMerCruiser 4.3\/4.3LX\/4.3 MPI; similar Volvo Penta V6 packages. Often 175–220 HP, with some performance variants higher.\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;\"\u003eLighter weight than V8, good fuel economy, widely supported components\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;\"\u003eMany accessories cross over with V8, but manifolds, ignition wire sets, and some brackets are platform‑specific—confirm 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\" style=\"padding:16px 0;\"\u003e\n  \u003ch2\u003eRoutine Maintenance \u0026amp; Service Parts\u003c\/h2\u003e\n  \u003cp\u003eIntervals below are general guidelines for typical GM‑based sterndrive packages. Always confirm specifications and torque values in your official 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 #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;\"\u003eEvery 100 hours or annually\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eUse marine‑grade oil; change more often in severe duty or high humidity\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\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 style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eGear oil (drive)\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eEvery 100 hours or annually\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eInspect for water intrusion (milky oil); replace seals if needed\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-service-maintenance-kits\"\u003eMerCruiser Service \u0026amp; Maintenance 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;\"\u003e200 hours or every 2 seasons\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eVerify heat range\/gap for your ignition and fuel system\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\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 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;\"\u003eInspect 50 hours; replace annually\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eDrain water as needed; carry a spare element onboard\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;\"\u003eAnnually or 100 hours (sooner in sandy\/silty water)\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eDrive‑mounted on many Alpha units; engine‑mounted on many Bravo\/V‑drive packages\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\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 style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eAnodes (corrosion protection)\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eInspect monthly; replace when ~50% depleted\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eMatch material (zinc\/aluminum\/magnesium) to your water type\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-anodes\"\u003eMerCruiser Anodes\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=\"padding:16px 0;\"\u003e\n  \u003ch2\u003eFrequently Used Parts Categories\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eRoutine Service Kits – \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\/mercruiser-impellers\"\u003eMerCruiser Impellers\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 and \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, \u003ca href=\"https:\/\/seasierra.com\/collections\/starters\"\u003eStarters\u003c\/a\u003e, \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-alternators\"\u003eMerCruiser Alternators\u003c\/a\u003e, \u003ca href=\"https:\/\/seasierra.com\/collections\/sensors\"\u003eSensors\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eExhaust \u0026amp; Manifolds – \u003ca href=\"https:\/\/seasierra.com\/collections\/manifolds\"\u003eManifolds\u003c\/a\u003e and related hardware\u003c\/li\u003e\n    \u003cli\u003eGearcase Seals \u0026amp; Hardware – \u003ca href=\"https:\/\/seasierra.com\/collections\/lower-unit-seal-kits\"\u003eLower Unit Seal Kits\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003ePropulsion Tuning – \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser-propellers\"\u003eMerCruiser Propellers\u003c\/a\u003e\n\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"troubleshooting\" style=\"padding:16px 0;\"\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 #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;\"\u003eOverheat alarm or weak discharge\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eInspect seawater intake for blockage, strainer condition, and impeller wear; verify thermostat operation\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eWater pump impeller\/kit, thermostat, intake screens\/hoses\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;\"\u003eCheck fuel filter\/water separator, anti‑siphon valve, and ignition components; confirm prop pitch\/load\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eFuel filter, fuel pump, spark plugs\/wires, propeller selection\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;\"\u003eTest battery voltage and grounds, inspect plugs and idle air system (EFI), check for vacuum leaks\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eSpark plugs, sensors (IAC\/MAP\/TPS depending on system), fuel injectors or carb kit\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eGearcase noise or metal in gear oil\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eVerify gear oil level\/condition; inspect magnetic drain plug and prop shaft for fishing line\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;border-bottom:1px solid #eee;\"\u003eLower unit seal kit, bearings, shims\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 0;\"\u003e\n  \u003ch2\u003eFAQs\u003c\/h2\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eAre parts interchangeable between different years or packages (MerCruiser, Volvo Penta, OMC)?\u003c\/summary\u003e\n    \u003cp\u003eCore GM long‑block items often interchange, but marinization parts (ignition, cooling, exhaust, brackets, pumps, sensors) are brand‑ and year‑specific. Use your engine and drive serial numbers to confirm.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhen should I replace the water pump impeller?\u003c\/summary\u003e\n    \u003cp\u003eAnnually or every 100 hours is a common rule. Replace sooner if operating in sandy\/silty water, if the stream is weak, or after any overheat event.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow often should I change the sterndrive gear oil?\u003c\/summary\u003e\n    \u003cp\u003eTypically every 100 hours or at least once per season. Always change immediately if you find milky oil (water intrusion) or metal on the magnetic drain plug.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat information do you need to verify part compatibility?\u003c\/summary\u003e\n    \u003cp\u003eProvide the engine serial number, drive serial number, model designation (e.g., 5.7L carb\/TBI\/EFI), year range if known, and the specific system\/part you’re servicing.\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? Browse our MerCruiser collection and use the filters to narrow by horsepower, year, and model.\u003c\/p\u003e\n  \u003ca href=\"https:\/\/seasierra.com\/collections\/mercruiser\" style=\"display:inline-block;padding:10px 14px;background:#0a5;border-radius:6px;color:#fff;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 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\/gm-250hp-4-stroke-marine-engine-parts.oembed","provider":"SeaSierra","version":"1.0","type":"link"}