{"product_id":"volvo-1386","title":"Volvo Penta HS1A Reverse Gear O-Ring 977890 | Inboard Transmission Seal","description":"\u003ch2\u003ePart Details\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e 977890\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Volvo Penta\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e O-ring — internal transmission valve\/housing seal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSystem:\u003c\/strong\u003e HS1A reverse gear \/ inboard transmission — internal hydraulic and mechanical assembly\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDiagram Position:\u003c\/strong\u003e Internal valve\/housing assembly — adjacent to cover 872567 and housing 872525\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncluded In:\u003c\/strong\u003e Gasket kit 876588 (HS1A transmission service kit)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eQty Per Assembly:\u003c\/strong\u003e 1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e Approx. 0.05 kg\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImportant:\u003c\/strong\u003e Replace at every disassembly — do not reuse a compressed or aged transmission O-ring\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eAbout This Part\u003c\/h2\u003e\n\u003cp\u003eGenuine Volvo Penta 977890 is an OEM O-ring used inside selected Volvo Penta HS1A marine reverse-gear and inboard transmission assemblies. Parts diagrams place 977890 directly beside cover 872567, housing 872525, sealing ring 872701, and related valve components within the transmission’s internal assembly. The HS1A transmission contains several different O-rings in close proximity — confirm the transmission model, ratio, and exact diagram position before ordering, as nearby seals 925058, 955983, 956000, 977891, 925260, and 925263 occupy different positions and are not interchangeable. For major HS1A overhaul work, 977890 is also included in complete gasket kit 876588.\u003c\/p\u003e\n\n\u003ch2\u003eCompatible Applications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eVolvo Penta HS1A — internal valve\/housing O-ring position\u003c\/li\u003e\n\u003cli\u003eVolvo Penta HS1A 1.96:1 — internal valve\/housing O-ring position\u003c\/li\u003e\n\u003cli\u003eVolvo Penta HS1A 2.62:1 — internal valve\/housing O-ring position\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eConfirm transmission model, gear ratio, and exact diagram position before ordering. Several different O-rings are used within the HS1A transmission — position matching from the exploded diagram is essential.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch2\u003eWhen to Replace\u003c\/h2\u003e\n\u003cp\u003eReplace this O-ring whenever the associated transmission cover or internal assembly is opened, and any time the existing seal shows:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eFlattening or permanent compression set\u003c\/li\u003e\n\u003cli\u003eHardening or brittleness from age or heat\u003c\/li\u003e\n\u003cli\u003eCuts, nicks, or tears\u003c\/li\u003e\n\u003cli\u003eSwelling or distortion\u003c\/li\u003e\n\u003cli\u003eAssociation with transmission-oil leakage at the covered area\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eFor complete HS1A overhaul service, gasket kit 876588 supplies this O-ring along with other seals required for a full rebuild.\u003c\/p\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003cp\u003eClean the O-ring groove and mating surfaces thoroughly before installation. Ensure the new seal is seated evenly and is not twisted or pinched during reassembly. Follow the applicable Volvo Penta HS1A workshop procedure for transmission disassembly, internal component adjustment, and final oil-level checks after reassembly.\u003c\/p\u003e\n\n\u003ch2\u003eRelated Parts in This Assembly\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCover:\u003c\/strong\u003e 872567 — adjacent component in the same internal assembly\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHousing:\u003c\/strong\u003e 872525 — adjacent component in the same internal assembly\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSealing ring:\u003c\/strong\u003e 872701 — sealing component in the same internal valve assembly\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHS1A transmission gasket kit:\u003c\/strong\u003e 876588 — complete seal kit for HS1A overhaul service (includes 977890)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRelated O-rings (different positions):\u003c\/strong\u003e 925058, 955983, 956000, 977891, 925260, 925263 — other seals in the same transmission; confirm positions from diagram\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eCross-Reference Part Numbers\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM:\u003c\/strong\u003e 977890\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncluded in gasket kit:\u003c\/strong\u003e 876588\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNote:\u003c\/strong\u003e No confirmed Volvo Penta OEM superseding number identified in current parts references.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eParts Desk Insight\u003c\/h2\u003e\n\u003cp\u003e977890 is specifically tied to the HS1A reverse-gear assembly and should not be treated as a general-purpose Volvo Penta O-ring. The most common ordering mistake is selecting an O-ring by size or appearance rather than diagram position, since several different seals sit close together in the HS1A internal assembly. If a full HS1A overhaul is being performed, ordering gasket kit 876588 rather than individual O-rings is usually more efficient, as it covers the complete set of internal seals required for a thorough rebuild.\u003c\/p\u003e","brand":"VOL","offers":[{"title":"Default Title","offer_id":43564069126180,"sku":"977890","price":6.1,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0743\/5799\/7604\/files\/images_89cd94d2-ab15-473a-96e5-0b1ad89607d7.png?v=1788650048","url":"https:\/\/marisolmarine.com\/products\/volvo-1386","provider":"Marisol Marine Company","version":"1.0","type":"link"}