841812 Double Alternator Pulley for Volvo Penta AD31 AD41 AQAD30 AQAD40 AQD40 D41 KAD42 KAMD42 MD30 MD31 MD40 MD70 TAMD102 TAMD103 TAMD121 TAMD122 TAMD30 TAMD31 TAMD40 TAMD41 TAMD42 TAMD70 THAMD70 TMD100 TMD120 TMD121 TMD30 TMD31 TMD40 TMD41 | JLM Marine

Double Alternator Pulley for Volvo Penta AD31 AD41 AQAD30 AQAD40 AQD40 D41 KAD42 KAMD42 MD30 MD31 MD40 MD70 TAMD102 TAMD103 TAMD121 TAMD122 TAMD30 TAMD31 TAMD40 TAMD41 TAMD42 TAMD70 THAMD70 TMD100 TMD120 TMD121 TMD30 TMD31 TMD40 TMD41

This dual belt alternator pulley is engineered for a comprehensive range of Volvo Penta marine diesel engines, including the AD31, AD41, AQAD30, AQAD40, AQD40, D41, KAD42, KAMD42, MD30, MD31, MD40, MD70, TAMD102, TAMD103, TAMD121, TAMD122, TAMD30, TAMD31, TAMD40, TAMD41, TAMD42, TAMD70, THAMD70, TMD100, TMD120, TMD121, and TMD series. Designed to fit Valeo and Volvo Penta alternators, this pulley ensures reliable power distribution across dual belt configurations in demanding marine environments.

This replacement pulley directly replaces OEM part number 841812, providing a cost-effective alternative while maintaining compatibility with original equipment specifications.

• Dual belt design for enhanced alternator drive capacity
• Compatible with Valeo and Volvo Penta alternators
• Direct fit for numerous Volvo Penta diesel engine series

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below.

Package Contents

• 1 × Double Alternator Pulley (OEM 841812)

Installation Guide

1. Disconnect the battery negative terminal to ensure safe working conditions. Allow the engine to cool completely before starting work.
2. Loosen the alternator mounting bolts and adjustment bracket to relieve belt tension. Remove both alternator drive belts from the existing pulley.
3. Using the appropriate tool, remove the retaining nut or bolt securing the old pulley to the alternator shaft. Carefully slide the old pulley off the shaft.
4. Clean the alternator shaft thoroughly to remove any debris, corrosion, or old lubricant. Inspect the shaft for wear or damage.
5. Align the new double pulley with the alternator shaft keyway (if applicable). Slide the pulley onto the shaft, ensuring it seats fully against the alternator housing.
6. Install and hand-tighten the retaining nut or bolt, then torque to manufacturer's specifications. Do not over-tighten, as this may damage the alternator bearings.
7. Route both alternator belts around the new double pulley and their respective driven pulleys. Ensure belts are properly seated in all pulley grooves.
8. Adjust belt tension by repositioning the alternator on its adjustment bracket. Proper tension allows approximately ½ inch deflection when pressed midway between pulleys.
9. Tighten all alternator mounting and adjustment bolts securely. Double-check that all fasteners are properly torqued.
10. Reconnect the battery negative terminal. Start the engine and observe pulley operation for any unusual noise, vibration, or belt slippage.
11. Run the engine for several minutes and re-check belt tension after the initial break-in period. Adjust if necessary.

Troubleshooting & FAQ

Q: How do I confirm this pulley fits my Volvo Penta alternator?
A: Verify your engine model in the compatibility table above and compare the pulley's dual-groove design with your existing part. Cross-reference OEM part number 841812 to ensure proper fitment.

Q: What are the signs that my alternator pulley needs replacement?
A: Common symptoms include squealing or chirping belts, visible cracks or wear on pulley grooves, belt slippage under load, or inconsistent charging performance. Physical damage or excessive wobble also indicates replacement is needed.

Q: Can I use this dual pulley if my alternator currently has a single-belt pulley?
A: This pulley is designed specifically for dual-belt alternator configurations on the listed Volvo Penta models. If your system uses a single belt, verify your engine specifications and alternator type before installation, as modifications to the belt routing system may be required.

Q: How often should I inspect or replace the alternator pulley?
A: Inspect the pulley during routine belt replacement intervals or at least annually. Replace if you observe cracks, significant groove wear, or if the pulley no longer maintains proper belt alignment and tension.

Q: Is this an OEM part or an aftermarket replacement?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.