Spark Plug Ignition Coil Wire Set – Fits Mercruiser 5.0L, 5.7L, 6.2L MPI V8 (Replaces 84-863656A1, 18-8828)
Spark Plug Ignition Coil Wire Set – Fits Mercruiser 5.0L, 5.7L, 6.2L MPI V8 (Replaces 84-863656A1, 18-8828) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Spark Plug Ignition Coil Wire Set – Fits Mercruiser 5.0L, 5.7L, 6.2...
Product Details
This Spark Plug Ignition Coil Wire Set is designed for a direct fit on a range of Mercruiser MPI V8 engines, including the 5.0L, 5.7L, and 6.2L sterndrive and inboard models equipped with flat cap distributors. It is primarily compatible with engines manufactured from the late 1990s through the mid-2000s.
This set serves as a direct replacement for Mercruiser 84-863656A1, Sierra 18-8828, CDI 631-0011, Indmar 751104, and Mallory 9-28009, ensuring a precise interchange for multiple part numbers.
- Engineered for direct-fit installation, no modification required.
- Constructed with silicone and stainless steel conductors to resist heat, vibration, and corrosion in marine environments.
- Includes eight spark plug wires and one coil wire for a complete replacement.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercruiser | 84-863656A1 / 84863656A1 |
| Sierra | 18-8828 / 18-8828-1 |
| CDI | 631-0011 |
| Indmar | 751104 / 756004 |
| Mallory | 9-28009 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This wire set is compatible with the following Mercruiser sterndrive and inboard engines.
| Brand | Model | Stroke | Years | OEM Part No. |
|---|---|---|---|---|
| Mercruiser | 5.0L MPI Alpha/Bravo | 4-Stroke | Late 1990s–2000s (s/n 0M300000 and up) | 84-863656A1 |
| Mercruiser | 5.0L MPI Alpha/Bravo EC | 4-Stroke | 2000s (s/n 1A300000 and up) | 84-863656A1 |
| Mercruiser | 350 Horizon Bobtail | 4-Stroke | 84-863656A1 | |
| Mercruiser | 350 MPI Alpha | 4-Stroke | 84-863656A1 | |
| Mercruiser | 350 MPI Alpha/Bravo | 4-Stroke | 84-863656A1 | |
| Mercruiser | 350 MPI Bravo | 4-Stroke | 84-863656A1 | |
| Mercruiser | 350 MAG MPI Alpha/Bravo | 4-Stroke | 84-863656A1 | |
| Mercruiser | 350 MAG MPI Horizon Alpha/Bravo | 4-Stroke | 84-863656A1 | |
| Mercruiser | 350 MAG MPI Horizon MIE | 4-Stroke | 84-863656A1 | |
| Mercruiser | 350 MAG MPI Horizon Alpha/Bravo EC | 4-Stroke | 2000s (s/n 1A300000 and up) | 84-863656A1 |
| Mercruiser | 350 MAG MPI MIE | 4-Stroke | 84-863656A1 | |
| Mercruiser | 350 MAG MPI SKI | 4-Stroke | 84-863656A1 | |
| Mercruiser | 5.7L MPI Horizon MIE | 4-Stroke | 2000s (s/n 1A090000 and up) | 84-863656A1 |
| Mercruiser | 5.7L MPI MIE | 4-Stroke | 2000s (s/n 1A090000 and up) | 84-863656A1 |
| Mercruiser | 5.7L MPI MIE EC | 4-Stroke | 2000s (s/n 1A090000 and up) | 84-863656A1 |
| Mercruiser | 5.7L MPI SKI | 4-Stroke | 2000s (s/n 1A090000 and up) | 84-863656A1 |
| Mercruiser | 5.7L MPI TOW | 4-Stroke | 84-863656A1 | |
| Mercruiser | 5.7L MPI SKI EC | 4-Stroke | 84-863656A1 | |
| Mercruiser | 5.7L MPI Towsport with GEN III | 4-Stroke | 2000s (s/n 1A091881 and up) | 84-863656A1 |
| Mercruiser | 377 MAG MPI Bravo | 4-Stroke | 2000s (s/n 1A300000 and up) | 84-863656A1 |
| Mercruiser | 377 MAG MPI Bravo EC | 4-Stroke | 2000s (s/n 1A343300 and up) | 84-863656A1 |
| Mercruiser | 383 MAG Stroker Bravo | 4-Stroke | 84-863656A1 | |
| Mercruiser | 383 MAG Stroker Inboard | 4-Stroke | 84-863656A1 | |
| Mercruiser | 383 MPI FWC Bravo | 4-Stroke | 84-863656A1 | |
| Mercruiser | 385 Performance Tuned | 4-Stroke | 84-863656A1 | |
| Mercruiser | 6.2L MPI Horizon MIE | 4-Stroke | 2000s (s/n 1A090000 and up) | 84-863656A1 |
| Mercruiser | 6.2L MPI MIE | 4-Stroke | 2000s (s/n 1A090000 and up) | 84-863656A1 |
| Mercruiser | 6.2L MPI MIE EC | 4-Stroke | 2000s (s/n 1A091600 and up) | 84-863656A1 |
| Mercruiser | MX 6.2L MPI Bravo | 4-Stroke | Late 1990s–2000s (s/n 0M300000–1A299999) | 84-863656A1 |
| Mercruiser | MX 6.2L MPI Horizon Bravo | 4-Stroke | Late 1990s–2000s (s/n 0M300000–1A299999) | 84-863656A1 |
| Mercruiser | MX 6.2L MPI Horizon MIE | 4-Stroke | Late 1990s–2000s (s/n 0M310000–1A089999) | 84-863656A1 |
| Mercruiser | MX 6.2L MPI MIE | 4-Stroke | Late 1990s–2000s (s/n 0M310000–1A089999) | 84-863656A1 |
| Mercruiser | MX 6.2L MPI SKI | 4-Stroke | Late 1990s–2000s (s/n 0M317000–0W689999) | 84-863656A1 |
Technical Specs
- Product Type
- Spark Plug Ignition Wire Set
- Installation
- Direct Fit Replacement
- Fuel Type
- Gasoline
- Connection Type
- Flat Cap Distributor
- Housing Material
- Silicone, Stainless Steel Conductors
- Wire Sizes
- 8 Spark Plug Wires + 1 Coil Wire
- Wire Lengths
- 2x 22" (55.9cm), 2x 27" (68.6cm), 2x 31" (78.7cm), 2x 36.5" (92.7cm), 1x 21" (53.3cm) Coil Wire
- Warranty
- 1 Year
- Other Attributes
- Designed to resist heat, vibration, and corrosion in marine environments
What’s in the Box
- 2 x Spark Plug Wires — 22 inches (55.9cm)
- 2 x Spark Plug Wires — 27 inches (68.6cm)
- 2 x Spark Plug Wires — 31 inches (78.7cm)
- 2 x Spark Plug Wires — 36.5 inches (92.7cm)
- 1 x Coil Wire — 21 inches (53.3cm)
Installation Notes
- Disconnect the boat's battery before beginning work.
- To avoid mixing up connections, replace one wire at a time. Start with the #1 cylinder.
- Gently twist and pull to remove the old wire's boot from the spark plug and the distributor cap.
- Select a new wire from the set that matches the length of the one you just removed.
- Apply a small amount of dielectric grease (not included) to the inside of each boot to prevent corrosion and ease future removal.
- Firmly press the new wire's boot onto the spark plug and distributor cap terminal until it clicks into place.
- Repeat the process for the remaining seven cylinders.
- Replace the main coil wire running from the ignition coil to the center of the distributor cap.
- Ensure all wires are securely routed away from hot or moving engine parts.
- Reconnect the battery and start the engine to test for smooth operation.
Troubleshooting & FAQ
How do I confirm these wires fit my specific engine?
The surest way is to match your existing part number to one listed in our Part Number Matrix. You can also check your engine model and serial number against our compatibility table. Always visually compare your old wires to our product images.
What are the signs of failing ignition wires?
Common symptoms include rough idling, engine misfires (especially under load), decreased power, poor fuel economy, and visible signs of wear like cracking, burning, or corrosion on the wire jackets or terminals.
How often should I replace my spark plug wires?
While there is no fixed interval, it is good practice to inspect them annually and consider replacement every 3-5 years or whenever you replace the spark plugs, depending on usage and operating conditions.
Are these wires different from the original Mercruiser ones?
These are aftermarket wires designed to meet or exceed OEM specifications for fit, form, and function. They are made from high-quality materials (silicone and stainless steel) to provide excellent heat resistance and electrical conductivity, similar to the original parts.
Can I install these wires myself?
Yes, this is a common DIY maintenance task for those with basic mechanical skills. The most important step is to replace wires one by one to ensure the correct firing order is maintained. However, if you are unsure, professional installation is always recommended.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost?
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns?
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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