Double Alternator Pulley – Fits Volvo Penta AD31 AD41 AQAD30 AQAD40 AQD40 (Replaces 841812)
Double Alternator Pulley – Fits Volvo Penta AD31 AD41 AQAD30 AQAD40 AQD40 (Replaces 841812) is backordered and will ship as soon as it is back in stock.
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Double Alternator Pulley – Fits Volvo Penta AD31 AD41 AQAD30 AQAD40...
Double Alternator Pulley – Fits Volvo Penta AD31 AD41 AQAD30 AQAD40 AQD40 (Replaces 841812) is backordered and will ship as soon as it is back in stock.
Product Details
This Double Alternator Pulley 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.
This aftermarket pulley directly replaces Volvo Penta OEM part number 841812, offering dependable interchange compatibility.
- Dual-belt design for high-output alternator applications
- Precision-machined for accurate belt alignment and reduced slippage
- Compatible with both freshwater and saltwater marine environments
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Volvo Penta | 841812 | OEM reference |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model |
|---|---|
| Volvo Penta | AD31B, AD31D-A, AD31L-A, AD31P-A |
| Volvo Penta | AD41A, AD41B, AD41D, AD41L-A, AD41P-A |
| Volvo Penta | AQAD30A, AQAD31A, AQAD40A, AQAD40B, AQAD41A |
| Volvo Penta | AQD40A, AQD70B, AQD70BL, AQD70CL, AQD70D |
| Volvo Penta | D41A, D41B, D41L-A |
| Volvo Penta | KAD42A, KAD42B, KAMD42A, KAMD42B |
| Volvo Penta | MD30A, MD31A, MD40A, MD70B, MD70C |
| Volvo Penta | TAMD102A, TAMD102D, TAMD103A-A, TAMD121C, TAMD122A, TAMD122C, TAMD122D, TAMD122P-A, TAMD122P-B, TAMD122P-C |
| Volvo Penta | TAMD30A, TAMD31A, TAMD31B, TAMD31D, TAMD31L-A, TAMD31M-A, TAMD31P-A, TAMD31S-A |
| Volvo Penta | TAMD40A, TAMD40B, TAMD41A, TAMD41B, TAMD41D, TAMD41H-A, TAMD41H-B, TAMD41M-A, TAMD41P-A, TAMD42B |
| Volvo Penta | TAMD70B, TAMD70C, TAMD70D, TAMD70E, THAMD70B, THAMD70C |
| Volvo Penta | TMD100C, TMD120B, TMD121C, TMD30A, TMD31A, TMD31B, TMD31D |
| Volvo Penta | TMD40A, TMD40B, TMD40C, TMD41A, TMD41B, TMD41D, TMD41L-A |
Technical Specs
- Part Type
- Double alternator pulley (dual-belt)
- Application
- Volvo Penta marine diesel engines
- Replaces OEM
- 841812
- Alternator Type
- Valeo / Volvo Penta
What's in the Box
- 1 × Double Alternator Pulley
Installation Notes
- Disconnect the negative battery terminal to prevent electrical shorts.
- Loosen the alternator mounting and adjustment bolts to relieve belt tension.
- Remove both drive belts from the old pulley.
- Remove the retaining nut or bolt securing the pulley to the alternator shaft.
- Slide the old pulley off the shaft, noting the orientation of any spacers or washers.
- Install the new double pulley onto the alternator shaft in the same orientation.
- Secure the pulley with the retaining nut or bolt, torquing to manufacturer specification.
- Route both drive belts onto the new pulley, ensuring proper alignment with all sheaves.
- Adjust alternator position to achieve correct belt tension (typically 10–15 mm deflection mid-span).
- Tighten all mounting and adjustment bolts securely.
- Reconnect the battery terminal and start the engine to verify proper alternator function and belt tracking.
Troubleshooting & FAQ
How do I know if this pulley fits my Volvo Penta engine?
Cross-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.
What causes alternator pulley failure?
Common 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.
Can I use a single-belt pulley instead of a double?
No. 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.
How often should I replace the alternator pulley?
Inspect 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.
Will this work with non-Valeo alternators?
This 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.
What tools are needed for installation?
You 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.
OEM vs. Aftermarket?
This 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.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered 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 & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications against your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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