Alternator 12V 115A – Fits Volvo Penta D1/D2/D4/D6 Series (Replaces 874502, 3803650)

$197.86 $316.00

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Delivery and Shipping

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If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This high-output Alternator 12V 115A – Fits Volvo Penta D1/D2/D4/D6 Series is an aftermarket replacement engineered for reliability in marine environments. It is designed as a direct fit for Volvo Penta D1/D2 series (13–75 HP, 2001–present) and select D4/D6 series diesel engines (180–435 HP).

It serves as a direct interchange for Volvo Penta part numbers 874502, 3803650, 3817662, 3840181, 3587218, and Mitsubishi numbers A3TR0091, A3TR0093, and A3TR0094.

Engineered as a direct OEM replacement for a hassle-free installation.
Delivers over 35A at idle speeds and approximately 100A at cruising RPM.
Built for demanding marine conditions with a 6-groove flat pulley design.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket brands.

Brand	Part Number
Volvo Penta	874502
Volvo Penta	3803650
Volvo Penta	3817662
Volvo Penta	3840181
Volvo Penta	3587218
Mitsubishi	A3TR0091
Mitsubishi	A3TR0093
Mitsubishi	A3TR0094

Engine & Model Compatibility

Confirm your engine model and year in the tables below. This alternator fits a wide range of Volvo Penta D-Series engines.

Volvo Penta D1/D2 Series

Brand	Model	Rated HP	Stroke	Years	OEM Part No.
Volvo Penta	D1-13	13	4-Stroke	2001–present	874502, 3817662
Volvo Penta	D1-20	20	4-Stroke	2001–present	874502, 3817662
Volvo Penta	D1-30, D1-30B, D1-30F	30	4-Stroke	2001–present	874502, 3803650
Volvo Penta	D2-40, D2-40B, D2-40F	40	4-Stroke	2001–present	874502, 3803650
Volvo Penta	D2-55, D2-55B, D2-55C, D2-55D, D2-55E, D2-55F	55	4-Stroke	2001–present	874502, 3803650
Volvo Penta	D2-75, D2-75B, D2-75C	75	4-Stroke	2003–present	874502

Volvo Penta D4/D6 Series

Brand	Model	Rated HP	Stroke	Years	OEM Part No.
Volvo Penta	D4-180I-B/C/D/E/F	180	4-Stroke	2003–present	874502
Volvo Penta	D4-210A-A/B, D4-210I-A/B	210	4-Stroke	2003–present	874502
Volvo Penta	D4-225A-B/C/D/E/F, D4-225I-B/C/D/E/F	225	4-Stroke	2003–present	874502
Volvo Penta	D4-260A-A/B/C/D/E/F, D4-260D-B/C/D/E/F, D4-260I-A/B/C/D/E/F	260	4-Stroke	2003–present	874502
Volvo Penta	D4-300A-A/C/D/E/F, D4-300D-A/C/D/E/F, D4-300I-A/C/D/E/F	300	4-Stroke	2003–present	874502
Volvo Penta	D6-280A-A/B/C/D/E, D6-280I-A/B/C/D/E	280	4-Stroke	2003–present	874502
Volvo Penta	D6-310A-A/B/C/D/E/F, D6-310D-A/B/C/D/E, D6-310I-A/B/C/D/E/F	310	4-Stroke	2003–present	874502
Volvo Penta	D6-330A-B/C/D/E/F, D6-330D-B/C/D/E/F, D6-330I-B/C/D/E/F	330	4-Stroke	2003–present	874502
Volvo Penta	D6-350A-A/B	350	4-Stroke	2003–present	874502
Volvo Penta	D6-370A-B/C/D/E/F, D6-370D-A/B/C/D/E/F, D6-370I-A/B/C/D/E/F	370	4-Stroke	2003–present	874502
Volvo Penta	D6-400A-E/F	400	4-Stroke	2003–present	874502
Volvo Penta	D6-435D-A/C/D/E/F, D6-435I-A/C/D/E/F, D6-435I-TC-F	435	4-Stroke	2003–present	874502

Technical Specs

Product Type: Marine Alternator
Installation: Direct OEM Replacement
Voltage: 12V
Amperage: 115A
Direction of Rotation: Clockwise (CW)
Pulley Type: 6-Groove Flat Pulley, 62mm diameter
Mounting: 3 Mounting Holes
Terminals: B+ (M8), W (M5x0.8), D (M4x0.7), S (Spade), B- (M6x1.00)
Mounting Hole Dimensions: Ear 1: 10.8mm, Ear 2: 13mm, Ear 3: 13.3mm (all unthreaded)
Idle Output: >35A at idle speed
Cruising Output: ~100A at cruising speed
Product Dimensions: 27.0 cm (L) x 23.0 cm (W) x 20.0 cm (H)
Weight: 7 kg (15.4 lbs)
Warranty: 1-2 Years (varies by retailer)

What’s in the Box

1 x Alternator (equivalent to 874502/3803650)

Installation Notes

Disconnect the boat's battery negative terminal before beginning work.
Identify and label all electrical wire connections to the old alternator, then disconnect them.
Loosen the belt tensioner pulley and carefully remove the serpentine belt from the alternator pulley.
Unbolt and remove the old alternator from its mounting brackets.
Visually compare the new alternator with the old unit to confirm identical mounting points and pulley configuration.
Position the new alternator and secure it with the mounting bolts, tightening them to the engine manufacturer's recommended torque specifications.
Re-install the serpentine belt, ensuring it is properly seated on all pulleys. Adjust the tensioner to the correct specification.
Reconnect the electrical wiring to the corresponding terminals on the new alternator.
Reconnect the battery negative terminal.
Start the engine and use a voltmeter to check the battery voltage. A reading of 13.8V–14.5V typically indicates a properly functioning charging system.

Troubleshooting & FAQ

How do I confirm this alternator fits my specific engine?

First, match your original part number to a number in our Part Number Matrix. Second, find your engine model and year in the compatibility tables. Finally, compare the product images and specifications (especially mounting points and pulley type) to your old alternator before purchasing.

What are common signs of a failing alternator?

Look for a battery warning light on your dashboard, dimming lights, a frequently weak or dead battery, or grinding/whining noises coming from the engine bay. A voltmeter reading below 13V at the battery while the engine is running also indicates a charging problem.

Is the 115A output an upgrade for my engine?

The 115A rating is a common and effective output for these Volvo Penta series, providing strong charging even at idle. It meets or exceeds the specifications of many original alternators, ensuring ample power for your vessel's electrical systems.

What maintenance is required for this alternator?

Marine alternators require minimal maintenance. Periodically inspect the drive belt for wear and proper tension. Also, ensure all electrical connections are clean, tight, and free of corrosion. No internal servicing is necessary.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. All parts are manufactured in an ISO 9002 facility and batch-inspected for quality and consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit is 5–15 days for most regions. Standard shipping is free; expedited options will appear at checkout if available for your location.

Warranty & returns

This product is covered by a 1-year warranty against manufacturing defects under normal marine use. If you encounter any issues, please contact our support team with your order details. Returns are accepted within our standard window, provided the item is unused and in its original condition. See our full policy page or reach out for instructions.

Safety & Important Info

Verify images and specifications against your original part before purchase. If anything differs—even if your model appears compatible—do not order.
This is an aftermarket replacement component, not an original equipment manufacturer (OEM) part.
Professional installation is strongly recommended for safety, proper function, and to prevent damage to the electrical system.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
Fast Global Fulfillment — We offer free standard delivery to most regions, with typical transit times of 5–15 days.
Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.

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