{"product_id":"double-alternator-pulley-fits-volvo-penta-ad31-ad41-aqad30-aqad40-aqd40-replaces-841812","title":"Double Alternator Pulley – Fits Volvo Penta AD31 AD41 AQAD30 AQAD40 AQD40 (Replaces 841812)","description":"\u003cstyle\u003e\n  .ss-table-wrap { overflow-x:auto; -webkit-overflow-scrolling:touch; }\n  table.ss-table { width:100%; border-collapse:collapse; min-width:640px; }\n  table.ss-table th, table.ss-table td {\n    padding:10px 12px; border:1px solid #e5e7eb; text-align:left; vertical-align:top;\n  }\n  table.ss-table th {\n    white-space:nowrap;\n    word-break:normal;\n    letter-spacing:normal;\n    font-weight:600;\n    background:#f8fafc;\n  }\n  @media (max-width:480px){\n    table.ss-table th, table.ss-table td { padding:8px 10px; font-size:14px; }\n  }\n\u003c\/style\u003e\n\n\u003ch2\u003eProduct Details\u003c\/h2\u003e\n\u003cp\u003eThis \u003cstrong\u003eDouble Alternator Pulley\u003c\/strong\u003e is designed for Volvo Penta marine diesel engines including AD31, AD41, AQAD30, AQAD40, AQD40, and numerous other models. Engineered as a dual-belt pulley for Valeo\/Volvo Penta alternators, it ensures proper charging system operation across a wide range of TAMD, TMD, MD, KAMD, and D-series engines.\u003c\/p\u003e\n\u003cp\u003eThis aftermarket pulley directly replaces Volvo Penta OEM part number 841812, offering dependable interchange compatibility.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eDual-belt design for high-output alternator applications\u003c\/li\u003e\n\u003cli\u003ePrecision-machined for accurate belt alignment and reduced slippage\u003c\/li\u003e\n\u003cli\u003eCompatible with both freshwater and saltwater marine environments\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003ePart Number Matrix\u003c\/h2\u003e\n\u003cp\u003eUse this matrix to confirm equivalent references across OEM and aftermarket.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Part Number Matrix\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth\u003eBrand\u003c\/th\u003e\n        \u003cth\u003ePart Number\u003c\/th\u003e\n        \u003cth\u003eNotes\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003e841812\u003c\/td\u003e\n        \u003ctd\u003eOEM reference\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eEngine \u0026amp; Model Compatibility\u003c\/h2\u003e\n\u003cp\u003eConfirm your engine model\/year in the table below.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Engine and Model Compatibility\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth\u003eBrand\u003c\/th\u003e\n        \u003cth\u003eModel\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eAD31B, AD31D-A, AD31L-A, AD31P-A\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eAD41A, AD41B, AD41D, AD41L-A, AD41P-A\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eAQAD30A, AQAD31A, AQAD40A, AQAD40B, AQAD41A\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eAQD40A, AQD70B, AQD70BL, AQD70CL, AQD70D\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eD41A, D41B, D41L-A\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eKAD42A, KAD42B, KAMD42A, KAMD42B\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eMD30A, MD31A, MD40A, MD70B, MD70C\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eTAMD102A, TAMD102D, TAMD103A-A, TAMD121C, TAMD122A, TAMD122C, TAMD122D, TAMD122P-A, TAMD122P-B, TAMD122P-C\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eTAMD30A, TAMD31A, TAMD31B, TAMD31D, TAMD31L-A, TAMD31M-A, TAMD31P-A, TAMD31S-A\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eTAMD40A, TAMD40B, TAMD41A, TAMD41B, TAMD41D, TAMD41H-A, TAMD41H-B, TAMD41M-A, TAMD41P-A, TAMD42B\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eTAMD70B, TAMD70C, TAMD70D, TAMD70E, THAMD70B, THAMD70C\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eTMD100C, TMD120B, TMD121C, TMD30A, TMD31A, TMD31B, TMD31D\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eVolvo Penta\u003c\/td\u003e\n        \u003ctd\u003eTMD40A, TMD40B, TMD40C, TMD41A, TMD41B, TMD41D, TMD41L-A\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specs\u003c\/h2\u003e\n\u003cdl\u003e\n  \u003cdt\u003ePart Type\u003c\/dt\u003e\n  \u003cdd\u003eDouble alternator pulley (dual-belt)\u003c\/dd\u003e\n  \u003cdt\u003eApplication\u003c\/dt\u003e\n  \u003cdd\u003eVolvo Penta marine diesel engines\u003c\/dd\u003e\n  \u003cdt\u003eReplaces OEM\u003c\/dt\u003e\n  \u003cdd\u003e841812\u003c\/dd\u003e\n  \u003cdt\u003eAlternator Type\u003c\/dt\u003e\n  \u003cdd\u003eValeo \/ Volvo Penta\u003c\/dd\u003e\n\u003c\/dl\u003e\n\n\u003ch2\u003eWhat's in the Box\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e1 × Double Alternator Pulley\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n\u003cli\u003eDisconnect the negative battery terminal to prevent electrical shorts.\u003c\/li\u003e\n\u003cli\u003eLoosen the alternator mounting and adjustment bolts to relieve belt tension.\u003c\/li\u003e\n\u003cli\u003eRemove both drive belts from the old pulley.\u003c\/li\u003e\n\u003cli\u003eRemove the retaining nut or bolt securing the pulley to the alternator shaft.\u003c\/li\u003e\n\u003cli\u003eSlide the old pulley off the shaft, noting the orientation of any spacers or washers.\u003c\/li\u003e\n\u003cli\u003eInstall the new double pulley onto the alternator shaft in the same orientation.\u003c\/li\u003e\n\u003cli\u003eSecure the pulley with the retaining nut or bolt, torquing to manufacturer specification.\u003c\/li\u003e\n\u003cli\u003eRoute both drive belts onto the new pulley, ensuring proper alignment with all sheaves.\u003c\/li\u003e\n\u003cli\u003eAdjust alternator position to achieve correct belt tension (typically 10–15 mm deflection mid-span).\u003c\/li\u003e\n\u003cli\u003eTighten all mounting and adjustment bolts securely.\u003c\/li\u003e\n\u003cli\u003eReconnect the battery terminal and start the engine to verify proper alternator function and belt tracking.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\u003cdetails\u003e\u003csummary\u003eHow do I know if this pulley fits my Volvo Penta engine?\u003c\/summary\u003e\u003cp\u003eCross-reference your engine model against the compatibility table above. If your engine uses OEM part number 841812, this pulley is a direct replacement. Verify belt count and alternator type before ordering.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat causes alternator pulley failure?\u003c\/summary\u003e\u003cp\u003eCommon causes include worn bearings, over-tensioned belts, corrosion from saltwater exposure, and age-related material fatigue. Squealing noises, battery undercharging, or visible belt misalignment are typical symptoms.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eCan I use a single-belt pulley instead of a double?\u003c\/summary\u003e\u003cp\u003eNo. Engines designed for dual-belt alternators require both belts to deliver the full charging current. Using a single-belt pulley will result in insufficient alternator output and potential belt failure.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eHow often should I replace the alternator pulley?\u003c\/summary\u003e\u003cp\u003eInspect the pulley annually for wear, cracks, or wobble. Replace if you notice damaged grooves, excessive play, or during alternator rebuild. Typically lasts 1,500–2,500 operating hours under normal conditions.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWill this work with non-Valeo alternators?\u003c\/summary\u003e\u003cp\u003eThis pulley is designed specifically for Valeo and Volvo Penta alternators used in the listed engine models. Confirm your alternator brand and shaft diameter before installation to ensure proper fit.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat tools are needed for installation?\u003c\/summary\u003e\u003cp\u003eYou will need standard metric sockets, a breaker bar or impact wrench, belt tension gauge (optional but recommended), and possibly a pulley puller if the old pulley is seized on the shaft.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eOEM vs. Aftermarket?\u003c\/summary\u003e\u003cp\u003eThis listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eShipping speed \u0026amp; cost\u003c\/summary\u003e\u003cp\u003eWe ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWarranty \u0026amp; returns\u003c\/summary\u003e\u003cp\u003eCovered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused \u0026amp; in original condition). See our policy page or reach out for instructions.\u003c\/p\u003e\u003c\/details\u003e\n\n\u003ch2\u003eSafety \u0026amp; Important Info\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eVerify images\/specifications against your original part. If anything differs—even if your model appears compatible—do not purchase.\u003c\/li\u003e\n\u003cli\u003eThis is an aftermarket replacement, not an OEM component.\u003c\/li\u003e\n\u003cli\u003eProfessional installation is recommended for safety and performance.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eAbout Sea Sierra\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003ePro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.\u003c\/li\u003e\n\u003cli\u003eFast Global Fulfillment — Free standard delivery to most regions in 5–15 days.\u003c\/li\u003e\n\u003cli\u003eManufacturer-Direct Value — Fair pricing without compromising on materials or QC.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":51025604346171,"sku":"21TP006","price":39.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/21TP006_1_189ab4a3-f072-4b23-9381-56b0712a1b1b.jpg?v=1772931718","url":"https:\/\/seasierra.com\/products\/double-alternator-pulley-fits-volvo-penta-ad31-ad41-aqad30-aqad40-aqd40-replaces-841812","provider":"SeaSierra","version":"1.0","type":"link"}