Mercury 862031T1 Alternator – 70 Amp | MerCruiser GM V6 & V8
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Mercury 862031T1 – Marine Alternator | 70 Amp | Serpentine Belt | MerCruiser GM V6 & V8
Part Number: 862031T1 | Supersedes: 862031T
Brand: Mercury Marine
Type: Marine Alternator Assembly
Output: 70 Amps
Style: Delco
Drive: Serpentine Belt
Pulley Diameter: 62 mm (approx. 2.4 in.)
GTIN/UPC: 745061543515
Genuine Mercury Marine replacement alternator for selected GM-powered MerCruiser sterndrive and inboard engines. Rated at 70 amps with a serpentine-belt drive and 62 mm pulley, 862031T1 replaces the earlier 862031T and is the correct choice for the accessory-drive configurations it fits. Keeping your charging system in top condition protects your battery, electronics, and overall electrical reliability on the water.
Compatible Applications
- 4.3L V6 MerCruiser – selected 1999–2001 configurations
- 5.0L V8 MerCruiser – selected configurations through serial 0M320024 (62 mm pulley)
- 5.7L / 350 MAG V8 MerCruiser – selected configurations
- 6.2L V8 MerCruiser – selected configurations
- Selected Alpha, Bravo, inboard, and ski configurations with serpentine belt drive
Serial Number Notice: Confirm your engine serial number and existing alternator pulley diameter before ordering. Some applications transition to a different alternator with a smaller 50 mm pulley at specific serial numbers. Always verify against your engine serial number and accessory-drive diagram.
Signs Your Alternator Needs Replacement
- Battery repeatedly discharging while the engine is running
- Charging-system warning light or low-voltage alarm
- Dim or flickering electrical accessories
- Difficulty maintaining battery voltage at idle or under load
When diagnosing charging issues, also inspect the battery, serpentine belt, belt tensioner, wiring, and terminal connections before replacing the alternator.
Installation Notes
- Disconnect battery power completely before beginning alternator service
- Inspect the serpentine belt and tensioner — replace if worn
- Check mounting brackets and pulley alignment
- Inspect all electrical terminals and charging cables for corrosion
- Tension the belt per the applicable MerCruiser service procedure after installation
- Verify charging voltage output after installation before returning to service
Part Numbers & Cross-Reference
- Mercury Marine: 862031T1
- Supersedes: 862031T
- Mercury Remanufactured: 862031R01
- Sierra: 18-6293
- Mallory: 9-19110
- ARCO: 20800
- Delco: 19020601 / 19020609
- GTIN/UPC: 745061543515
Parts Desk Insights
The key identifiers for 862031T1 are the serpentine belt drive and the 62 mm pulley. Several MerCruiser alternators look similar but use a smaller 50 mm pulley — ordering the wrong one is the most common mistake with this part. Always confirm the pulley diameter on the existing alternator and cross-check against your engine serial number before purchasing. 862031T1 supersedes the earlier 862031T, so if your service manual references 862031T, this is the current replacement. For charging system issues, customers often find the belt or tensioner also needs attention at the same time.
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.