{"product_id":"mercury-19-34270-expansion-plug","title":"Mercury 19-34270 Expansion Plug","description":"\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0056\/9429\/2079\/files\/66102c75f8d746adc03b88e1_brand-mercury-precision-parts.png?v=1777130741\" alt=\"\"\u003e\u003c\/p\u003e\n\u003cdiv class=\"qMYqUG_convSearchResultHighlightRoot\"\u003e\n\u003cdiv class=\"\" data-turn-id-container=\"request-69ea37f2-9634-83ea-95ed-3658eca80b3e-0\" data-is-intersecting=\"true\"\u003e\n\u003cdiv class=\"relative w-full overflow-visible\"\u003e\n\u003csection class=\"text-token-text-primary w-full focus:outline-none has-data-writing-block:pointer-events-none [\u0026amp;:has([data-writing-block])\u0026gt;*]:pointer-events-auto R6Vx5W_threadScrollVars scroll-mb-[calc(var(--scroll-root-safe-area-inset-bottom,0px)+var(--thread-response-height))] scroll-mt-[calc(var(--header-height)+min(200px,max(70px,20svh)))]\" dir=\"auto\" data-turn-id=\"request-69ea37f2-9634-83ea-95ed-3658eca80b3e-0\" data-turn-id-container=\"request-69ea37f2-9634-83ea-95ed-3658eca80b3e-0\" data-testid=\"conversation-turn-220\" data-scroll-anchor=\"false\" data-turn=\"assistant\"\u003e\n\u003cdiv class=\"text-base my-auto mx-auto pb-10 [--thread-content-margin:var(--thread-content-margin-xs,calc(var(--spacing)*4))] @w-sm\/main:[--thread-content-margin:var(--thread-content-margin-sm,calc(var(--spacing)*6))] @w-lg\/main:[--thread-content-margin:var(--thread-content-margin-lg,calc(var(--spacing)*16))] px-(--thread-content-margin)\"\u003e\n\u003cdiv class=\"[--thread-content-max-width:40rem] @w-lg\/main:[--thread-content-max-width:48rem] mx-auto max-w-(--thread-content-max-width) flex-1 group\/turn-messages focus-visible:outline-hidden relative flex w-full min-w-0 flex-col agent-turn\"\u003e\n\u003cdiv class=\"flex max-w-full flex-col gap-4 grow\"\u003e\n\u003cdiv data-message-author-role=\"assistant\" data-message-id=\"c6197508-bb78-42e6-9591-9bc20ad4357c\" dir=\"auto\" data-message-model-slug=\"gpt-5-5\" class=\"min-h-8 text-message relative flex w-full flex-col items-end gap-2 text-start break-words whitespace-normal outline-none keyboard-focused:focus-ring [.text-message+\u0026amp;]:mt-1\" data-turn-start-message=\"true\" tabindex=\"0\"\u003e\n\u003cdiv class=\"flex w-full flex-col gap-1 empty:hidden\"\u003e\n\u003cdiv class=\"markdown prose dark:prose-invert wrap-break-word w-full light markdown-new-styling\"\u003e\n\u003ch2 data-section-id=\"12kpvs2\" data-start=\"0\" data-end=\"36\"\u003eMercury 19-34270 Expansion Plug\u003c\/h2\u003e\n\u003cp data-start=\"39\" data-end=\"322\"\u003eMaintain proper engine sealing and cooling system reliability with the Mercury 19-34270 Expansion Plug. Designed as a genuine OEM replacement, this marine expansion plug helps seal engine block passages and protect critical cooling system components from coolant leaks and corrosion.\u003c\/p\u003e\n\u003cp data-start=\"324\" data-end=\"750\"\u003eExpansion plugs, often referred to as freeze plugs or core plugs, play an important role in sealing casting passages within the engine block. Over time, exposure to coolant, moisture, and repeated heat cycles can cause plugs to corrode or weaken, potentially leading to leaks and cooling system issues. Replacing worn or damaged expansion plugs helps preserve engine integrity and maintain dependable performance on the water.\u003c\/p\u003e\n\u003cp data-start=\"752\" data-end=\"1066\"\u003eBuilt to Mercury Marine factory specifications, the 19-34270 expansion plug is manufactured using durable marine-grade materials designed to withstand harsh marine environments. Engineered as a direct replacement, it provides reliable fitment and long-lasting sealing performance for compatible MerCruiser engines.\u003c\/p\u003e\n\u003chr data-start=\"1068\" data-end=\"1071\"\u003e\n\u003ch3 data-section-id=\"lmqikf\" data-start=\"1073\" data-end=\"1101\"\u003eCommon Engine Fitments\u003c\/h3\u003e\n\u003cp data-start=\"1102\" data-end=\"1214\"\u003eThe Mercury 19-34270 expansion plug is commonly used on select MerCruiser and Mercury Marine engines, including:\u003c\/p\u003e\n\u003cul data-start=\"1216\" data-end=\"1354\"\u003e\n\u003cli data-section-id=\"9eyza6\" data-start=\"1216\" data-end=\"1238\"\u003eMerCruiser 4.3L V6\u003c\/li\u003e\n\u003cli data-section-id=\"jlix76\" data-start=\"1239\" data-end=\"1261\"\u003eMerCruiser 5.0L V8\u003c\/li\u003e\n\u003cli data-section-id=\"xlwk5x\" data-start=\"1262\" data-end=\"1284\"\u003eMerCruiser 5.7L V8\u003c\/li\u003e\n\u003cli data-section-id=\"ei4nmu\" data-start=\"1285\" data-end=\"1307\"\u003eMerCruiser 350 MAG\u003c\/li\u003e\n\u003cli data-section-id=\"sc8cpv\" data-start=\"1308\" data-end=\"1330\"\u003eMerCruiser 377 MAG\u003c\/li\u003e\n\u003cli data-section-id=\"1uz23bd\" data-start=\"1331\" data-end=\"1354\"\u003eMerCruiser 6.2L MPI\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"1356\" data-end=\"1394\"\u003eThese engines are frequently found in:\u003c\/p\u003e\n\u003cul data-start=\"1396\" data-end=\"1591\"\u003e\n\u003cli data-section-id=\"wmzc5h\" data-start=\"1396\" data-end=\"1432\"\u003eSea Ray sport boats and cruisers\u003c\/li\u003e\n\u003cli data-section-id=\"17p41j7\" data-start=\"1433\" data-end=\"1471\"\u003eChaparral SSi and Signature series\u003c\/li\u003e\n\u003cli data-section-id=\"o2iy28\" data-start=\"1472\" data-end=\"1501\"\u003eFour Winns Horizon models\u003c\/li\u003e\n\u003cli data-section-id=\"1489p73\" data-start=\"1502\" data-end=\"1526\"\u003eBayliner sport boats\u003c\/li\u003e\n\u003cli data-section-id=\"agafyp\" data-start=\"1527\" data-end=\"1563\"\u003eCrownline bowriders and cruisers\u003c\/li\u003e\n\u003cli data-section-id=\"13w04fa\" data-start=\"1564\" data-end=\"1591\"\u003eRegal performance boats\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"1593\" data-end=\"1784\"\u003eThe 19-34270 plug is commonly used in engine block and cooling system applications where maintaining a proper seal is essential for preventing coolant leaks and preserving engine reliability.\u003c\/p\u003e\n\u003cp data-start=\"1786\" data-end=\"1951\"\u003eFitment can vary depending on engine serial number and block configuration, so confirming compatibility with part number \u003cstrong data-start=\"1907\" data-end=\"1919\"\u003e19-34270\u003c\/strong\u003e before ordering is recommended.\u003c\/p\u003e\n\u003chr data-start=\"1953\" data-end=\"1956\"\u003e\n\u003ch3 data-section-id=\"1iz91iu\" data-start=\"1958\" data-end=\"1974\"\u003eKey Features\u003c\/h3\u003e\n\u003cul data-start=\"1975\" data-end=\"2308\"\u003e\n\u003cli data-section-id=\"17kxajc\" data-start=\"1975\" data-end=\"2020\"\u003eGenuine Mercury Marine OEM expansion plug\u003c\/li\u003e\n\u003cli data-section-id=\"14wwrq0\" data-start=\"2021\" data-end=\"2065\"\u003eHelps seal engine block cooling passages\u003c\/li\u003e\n\u003cli data-section-id=\"15wk1t4\" data-start=\"2066\" data-end=\"2120\"\u003eDesigned for MerCruiser marine engine applications\u003c\/li\u003e\n\u003cli data-section-id=\"z2u4nv\" data-start=\"2121\" data-end=\"2190\"\u003eMarine-grade construction for corrosion resistance and durability\u003c\/li\u003e\n\u003cli data-section-id=\"1h20sdn\" data-start=\"2191\" data-end=\"2248\"\u003eHelps prevent coolant leaks and cooling system issues\u003c\/li\u003e\n\u003cli data-section-id=\"iy0gvr\" data-start=\"2249\" data-end=\"2308\"\u003eDirect-fit replacement for straightforward installation\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"2310\" data-end=\"2313\"\u003e\n\u003ch3 data-section-id=\"fcxgff\" data-start=\"2315\" data-end=\"2351\"\u003eWhy Replace an Expansion Plug?\u003c\/h3\u003e\n\u003cp data-start=\"2352\" data-end=\"2584\"\u003eOver time, expansion plugs can corrode or weaken from constant exposure to coolant and moisture. Replacing worn plugs helps maintain proper cooling system integrity and prevents leaks that could lead to overheating or engine damage.\u003c\/p\u003e\n\u003cp data-start=\"2586\" data-end=\"2773\" data-is-last-node=\"\" data-is-only-node=\"\"\u003eIf you’re servicing a compatible MerCruiser-powered boat, the Mercury 19-34270 expansion plug delivers the OEM-quality fit and dependable sealing performance your engine was designed for.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"z-0 flex min-h-[46px] justify-start\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv class=\"mt-3 w-full empty:hidden\"\u003e\n\u003cdiv class=\"text-center\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003cdiv class=\"contents\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Inboard Parts HQ","offers":[{"title":"Default Title","offer_id":48772556456193,"sku":"710-19-34270","price":8.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0056\/9429\/2079\/files\/Screenshot2026-05-15125455.png?v=1778864112","url":"https:\/\/inboardpartshq.com\/products\/mercury-19-34270-expansion-plug","provider":"Inboard Parts HQ","version":"1.0","type":"link"}