Arco 12V Starter Solenoid for Mercury & MerCruiser (SW109)
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
Arco 12V Starter Solenoid for Mercury & MerCruiser
A direct-replacement starter solenoid built specifically for Mercury outboard and MerCruiser sterndrive applications. This 12-volt solenoid features an isolated base design for clean, reliable installation and is engineered to meet or exceed original equipment specifications. If your engine is cranking slowly, clicking, or not engaging the starter at all, a failed solenoid is one of the first things to check — and this is the correct replacement for Mercury and MerCruiser systems.
Key Features
- 12 Volt — Matches standard marine electrical system voltage
- Isolated Base — Prevents grounding issues and simplifies installation
- Direct OEM Replacement — Engineered to meet or exceed original equipment specifications
- Marine-Grade Construction — Built for the corrosive marine environment
Specifications
- Voltage: 12V
- Base: Isolated
- Part Number: SW109
- SKU: 57-SW109
Compatible Applications
- Mercury outboard engines
- MerCruiser sterndrive engines
- Applications requiring a 12V isolated-base starter solenoid
Parts Desk Insights
Best Use Case: This solenoid is the go-to replacement for Mercury and MerCruiser owners experiencing no-start or intermittent starting issues where the starter motor itself is known to be good. The isolated base is important — it means the solenoid body is not grounded through its mounting surface, which is the correct configuration for most Mercury and MerCruiser applications. If you’re also replacing the starter, see our full range of engine electrical components for compatible starters and charging system parts. Always verify your engine’s specific model and year against the part number before ordering.
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.