Sierra 18-5882 Marine Alternator – Volvo Penta 12V 75A Serpentine
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
The Sierra 18-5882 is a 12-volt, 75-amp marine replacement alternator built for compatible Volvo Penta inboard engine applications. It uses a serpentine pulley configuration and is designed to match the mounting, electrical connections, and output specifications of the original Volvo Penta unit — making it a direct-replacement option when the OEM alternator needs to be replaced due to failure, wear, or electrical fault.
Sierra cross-references the 18-5882 directly to Volvo Penta OEM alternator 3884950 and ARCO 60073. The application covers GM 2007-and-newer style serpentine alternator installations used in Volvo Penta inboard configurations.
Fitment note: Volvo Penta has used multiple alternator designs across different engine families and production years. Confirm your existing alternator number, mounting configuration, pulley type, and electrical connections before ordering. The OEM number stamped on your current alternator is the most reliable fitment check.
Compatible Applications
- Volvo Penta inboard marine engines specifying OEM alternator 3884950
- GM 2007-and-newer style serpentine alternator applications in Volvo Penta inboard installations
- Verify fitment by confirming the OEM alternator number on your existing unit matches Volvo Penta 3884950 or ARCO 60073
- Confirm mounting ear configuration, serpentine pulley, and electrical terminal layout match before installing
Part Information
- Sierra part number: 18-5882
- SKU: 47-5882
- Brand: Sierra International
- Type: Marine replacement alternator
- Voltage: 12V
- Output: 75 amps
- Pulley type: Serpentine
- Application: Volvo Penta inboard engines (GM 2007+ style serpentine configuration)
- Fitment standard: Matches OEM mounting, electrical connections, and output specifications
- Weight: 5,257g (~11.6 lbs)
- UPC: 808282291785
- Condition: New
OEM Cross-Reference Numbers
- Sierra: 18-5882
- Volvo Penta: 3884950
- ARCO: 60073
- UPC: 808282291785
When Replacement Is Needed
- Battery is not holding charge or charging voltage is below 13.8V at operating RPM
- Warning light or gauge indicating low or no charge output
- Bearing noise, grinding, or whining from the alternator body
- Intermittent or erratic charging output
- Visible pulley damage, burnt terminals, or failed diode/regulator testing
- Always test the full charging circuit (wiring, connections, and belt) before condemning the alternator itself
Installation Notes
- Disconnect battery power at both terminals before beginning alternator removal or installation
- Before installing: compare mounting ears, electrical terminal positions, pulley type, and belt alignment with the removed unit to confirm correct fit
- Set serpentine belt tension according to the Volvo Penta service procedure for your engine model
- Reconnect all electrical terminals securely — a loose charging wire connection is a common cause of post-installation charging complaints
- After startup, verify charging voltage at the battery terminals (13.8–14.4V at cruise RPM indicates a healthy system)
- Inspect belt condition and all wiring connections at the time of replacement — a worn belt or corroded ground will shorten the life of a new alternator
Technical FAQ
Q: How do I confirm this alternator fits my Volvo Penta engine?
The fastest confirmation is the OEM part number on your existing alternator — if it shows Volvo Penta 3884950, the Sierra 18-5882 is the correct replacement. You can also cross-reference via ARCO 60073. Confirm the serpentine pulley configuration, mounting bracket, and terminal layout match before ordering.
Q: What’s the difference between this and the ARCO 60073?
Both the Sierra 18-5882 and the ARCO 60073 are aftermarket replacements for Volvo Penta 3884950. They serve the same application and cross-reference to the same OEM number. The ARCO 60072 Volvo Penta Alternator is a related but different unit — verify your OEM number matches 3884950 specifically before ordering either part.
Q: My new alternator isn’t charging after installation — what should I check?
First check belt tension — a loose serpentine belt is the most common cause of low or no output after installation. Then check all terminal connections including the main charging wire and the ground. Measure voltage at the battery with the engine at cruise RPM — a reading at or below battery voltage means the charging circuit isn’t completing, not necessarily that the alternator is faulty.
Q: Is this alternator ignition-protected for marine use?
Sierra marine alternators are built to marine ignition-protection standards required for enclosed engine compartments. Do not substitute an automotive alternator in a marine application — non-ignition-protected units are a fire risk in enclosed engine spaces.
Q: Does this alternator come with a pulley?
The 18-5882 includes the serpentine pulley as part of the unit configuration for this application. Confirm the pulley specification matches your existing setup before installation.
Related Marine Alternators & Charging Products
- Arco 60072 Volvo Penta Alternator — related Volvo Penta alternator; verify OEM number before ordering
- Marine Alternator 12V 75A – Replaces Volvo Penta 3862665 / 3884950 | SKU 57-60073
- Marine Alternator 12V 55A – Replaces MerCruiser 817119A1 | SKU 57-60050
- Marine Alternator 12V 65A – Replaces MerCruiser 805447T | SKU 57-60065
- Marine Alternator 12V 70A – Self-Exciting, Ignition Protected | SKU 57-20104
- Sierra Marine Alternator – High-Output Charging System
- Sierra BS11010 Battery Disconnect Switch with Alternator Field Disconnect
Parts Desk Insights
The Sierra 18-5882 is one of the cleaner alternator fitments in the Volvo Penta catalog because the OEM cross-reference to 3884950 is unambiguous — if that number is on your existing alternator, this is the correct Sierra replacement. The 12V/75A output and serpentine pulley also help distinguish it from other Volvo Penta alternators that look similar but use a different pulley or output rating. Best use case is a straightforward like-for-like replacement during a charging system service on a compatible Volvo Penta inboard. The most common issue we see is customers receiving the correct part and then finding the charging problem persists — almost always this turns out to be a belt tension issue or a corroded connection rather than a faulty alternator. Before assuming the new unit is at fault, check serpentine belt tension first (it’s the quickest thing to miss during reassembly), then verify all terminal connections are clean and tight. A loose or corroded main charging wire connection will cause exactly the same symptoms as a failed alternator.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.