Spark Plug Wire Set – Fits Mercruiser, Volvo Penta 5.0L, 5.7L (Replaces 3888328, 816608Q61)
Spark Plug Wire Set – Fits Mercruiser, Volvo Penta 5.0L, 5.7L (Replaces 3888328, 816608Q61) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Spark Plug Wire Set – Fits Mercruiser, Volvo Penta 5.0L, 5.7L (Repl...
Product Details
This aftermarket Spark Plug Wire Set is designed for a precise fit on Mercruiser V8 5.0L and 5.7L GM-MPI sterndrive engines with Thunderbolt ignition systems, and Volvo Penta V8 5.0L and 5.7L GXI, GI, and OSI sterndrive engines that use a flat top distributor. The high-performance silicone jacket and stainless steel conductors ensure reliable ignition and long-term durability in marine environments.
This kit serves as a direct replacement for a wide range of part numbers, including Volvo 3888328 and 3859000, Mercruiser 816608Q61, and Sierra 18-8804, ensuring broad compatibility. See the Part Number Matrix for a complete list of cross-references.
- Installs directly as a replacement for original factory wires.
- Engineered specifically for marine use with high resistance to moisture and corrosion.
- Includes a complete set of nine wires in various lengths for a full engine service.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Volvo | 3888328 |
| Volvo | 3859000 |
| Mercruiser | 816608Q61 |
| Mercruiser | 816608A61 |
| Mercruiser | 816761A15 |
| Mercruiser | 816761A2 |
| Mercruiser | 813720A2 |
| Mercruiser | 43376A2 |
| Mercruiser | 42841A5 |
| Mercruiser | 43376A1 |
| Mercruiser | 43376A14 |
| Mercruiser | 816608Q83 |
| Mallory | 9-28001 |
| Mallory | 9-28002 |
| Sierra | 18-8804 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercruiser models, these wires are designed for V8 GM-MPI sterndrive engines equipped with Thunderbolt ignition systems.
| Brand | Model | Rated HP | Stroke | OEM Part No. |
|---|---|---|---|---|
| Mercruiser | V8 5.0L GM-MPI Sterndrive | 5.0L | 4-Stroke | 816608Q61 |
| Mercruiser | V8 5.7L GM-MPI Sterndrive | 5.7L | 4-Stroke | 816608Q61 |
For Volvo Penta models, compatibility requires engines to have a flat top distributor. Please verify your distributor type before ordering.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Volvo Penta | V8 5.0L GXI | 5.0L | 4-Stroke | 3888328 | Requires flat top distributor |
| Volvo Penta | V8 5.0L GI | 5.0L | 4-Stroke | 3888328 | Requires flat top distributor |
| Volvo Penta | V8 5.0L OSI | 5.0L | 4-Stroke | 3888328 | Requires flat top distributor |
| Volvo Penta | V8 5.7L GXI | 5.7L | 4-Stroke | 3888328 | Requires flat top distributor |
| Volvo Penta | V8 5.7L GI | 5.7L | 4-Stroke | 3888328 | Requires flat top distributor |
| Volvo Penta | V8 5.7L OSI | 5.7L | 4-Stroke | 3888328 | Requires flat top distributor |
Technical Specs
- Product Type
- Marine Ignition Wire Set
- Installation
- Direct fit replacement
- Fuel Type
- Gasoline
- Connection
- Fits standard spark plug terminals and distributor cap
- Housing Material
- Silicone jacket with stainless steel conductors
- Housing Color
- Red
- Dimensions
- Various lengths: 35cm-89cm (13.8"-35")
- Weight
- 0.66 kg (1.46 lbs)
- Fitting Type
- Direct plug-in terminal connectors
- Other Technical Attributes
- Designed for marine engine use with high resistance to moisture, corrosion
What’s in the Box
- 9 x Spark Plug Wires consisting of:
- 2 x Spark Plug Wire, 89cm/35 inch
- 2 x Spark Plug Wire, 76cm/29.9 inch
- 2 x Spark Plug Wire, 67cm/26.4 inch
- 2 x Spark Plug Wire, 53.5cm/21.1 inch
- 1 x Spark Plug Wire, 35cm/13.8 inch
Installation Notes
- Ensure the engine is cool and the battery is disconnected before starting.
- Work on one spark plug wire at a time to avoid mixing up the firing order. Remove the old wire from the spark plug and distributor cap.
- Compare the new wire's length to the old one to ensure a match.
- Apply a small amount of dielectric grease to the inside of both boots of the new wire to seal against moisture and ease future removal.
- firmly push one end onto the spark plug terminal until it clicks into place.
- Route the new wire along the same path as the original, securing it with any existing clips or looms.
- Connect the other end to the corresponding terminal on the distributor cap, ensuring it seats fully with a click.
- Repeat this process for all remaining wires.
- Once all wires are replaced, reconnect the battery and start the engine to test for smooth operation.
Troubleshooting & FAQ
How do I know if these wires fit my engine?
This set fits specific Mercruiser V8 models with Thunderbolt ignition and Volvo Penta V8 models with a flat top distributor. Please check the compatibility tables and notes on this page. The most important step is to verify your engine model and distributor type before ordering.
One of the wires seems too short. What should I do?
First, double-check that you are matching the correct length wire to the correct cylinder according to the factory routing diagram for your engine. If a wire is still too short, such as the coil wire for a Volvo Penta 5.0 GXI as some users have noted, please contact our support team with your engine details for assistance.
What are the signs of failing spark plug wires?
Common symptoms include rough idling, engine misfires, poor acceleration, decreased fuel economy, and visible signs of wear on the wires themselves, such as cracks, burns, or corrosion on the terminals.
How often should I replace my spark plug wires?
Replacement intervals vary by engine manufacturer and usage, but a general guideline for marine environments is every 300-500 operating hours or every 3-5 years, whichever comes first. Consult your engine's service manual for specific recommendations.
Is dielectric grease necessary for installation?
Yes, applying a small amount of dielectric grease to the inside of the boots is highly recommended. It creates a moisture-proof seal, prevents corrosion, and makes future wire removal much easier without damaging the components.
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.
Payment & Security
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