Sierra 18-5187
Sierra 18-5187 — Product description
Keep your outboard motor firing on all cylinders with the Sierra 18-5187 ignition coil—a rugged, reliable component built for the demands of marine environments. Whether you're chasing fish offshore or cruising the bay, a strong ignition coil ensures consistent spark delivery, preventing those frustrating dead starts that kill a perfect day on the water.
Why Your Boat Needs a Top-Quality Ignition Coil
The ignition coil is the heart of your engine's spark system, transforming low-voltage battery power into the high-voltage jolt needed to ignite the fuel-air mixture. In harsh saltwater conditions, stock coils can fail prematurely due to corrosion, heat, or vibration. The Sierra 18-5187 steps in as a direct OEM-style replacement, engineered to match or exceed factory specs for seamless performance.
Standout Features of the Sierra 18-5187
- Durable Construction: Epoxy-filled housing resists moisture, salt spray, and impacts—ideal for boaters in coastal waters.
- Precise Winding: High-output secondary winding delivers up to 40,000 volts for hotter sparks and smoother idling.
- Compact Design: Matches original dimensions for plug-and-play fitment, no modifications required.
- Universal Mounting: Secure tabs and hardware ensure vibration-proof installation on rocker arm or canister-style setups.
Real-World Benefits for Boaters
Imagine heading out at dawn, only to have your engine sputter because of a weak coil. With the Sierra 18-5187, you get dependable starts even after sitting through winter storage. It reduces misfires that lead to rough running or fouled plugs, boosting fuel efficiency and extending the life of your points, condenser, and stator. Boaters report fewer breakdowns and more time enjoying the ride, making it a smart upgrade for weekend warriors and charter captains alike.
Compatibility at a Glance
This ignition coil serves as a drop-in replacement for select Johnson, Evinrude, and OMC outboards from the late '80s through early 2000s. It's commonly cross-referenced with OEM numbers like 582461 or similar in 65-125 HP two-cylinder models. Always verify against your engine's service manual or parts diagram to confirm fit—peace of mind starts with the right match.
Step-by-Step Installation Guide
Swapping out your old coil takes about 30 minutes with basic tools. Here's how:
- Disconnect the battery and remove the cowling for access.
- Unplug the high-tension lead from the coil tower and detach the primary wires.
- Loosen mounting screws and lift out the old coil.
- Position the new Sierra 18-5187, secure with original hardware, and reconnect wires (observe polarity).
- Reattach the HT lead, reinstall cowling, and test-fire the engine.
Pro Tip: Clean terminals with electrical contact cleaner to prevent future corrosion. Gap your points to spec (typically .016-.020 inches) for optimal spark.
Spotting Ignition Coil Failure Early
Don't wait for total breakdown. Watch for these symptoms:
- Hard starting or no-start conditions, especially when warm.
- Intermittent misfires under load or at idle.
- Weak spark visible during plug checks (under 20kV).
- Carbon tracking on the coil body from arcing.
Regular inspections during tune-ups can catch issues before they strand you miles from the dock.
Maintenance Tips to Maximize Longevity
Treat your ignition system right: Flush the engine after saltwater runs, apply dielectric grease to connections, and store the boat with a trickle charger. Pairing the Sierra 18-5187 with fresh plugs and a quality condenser keeps everything humming season after season.
Frequently Asked Questions
What engines is the Sierra 18-5187 ignition coil compatible with?
It's a direct replacement for many Johnson/Evinrude/OMC outboards in the 65-125 HP range from 1986-2001 two-cylinder models. Cross-check your OEM part number for exact fit.
How do I know if my ignition coil is bad?
Look for hard starting, misfires, or weak spark on plug tests. A multimeter can check primary resistance (around 0.5-1.5 ohms) and secondary (8-12k ohms).
Can I install the Sierra 18-5187 myself?
Yes, it's a straightforward DIY job with basic tools. Disconnect power first, follow the steps, and double-check connections.
Does this coil work in saltwater environments?
Absolutely—its epoxy-sealed design fights corrosion better than many stocks, perfect for coastal boating.
What's the difference between this and OEM coils?
Sierra matches OEM specs at a fraction of the cost, with comparable durability tested for marine abuse.
How often should I replace my ignition coil?
Every 3-5 years or at the first sign of trouble, especially in high-use or saltwater boats.
Will this improve my engine's performance?
It restores factory spark strength, leading to smoother running, better starts, and potential fuel savings—no power gains beyond stock.
SKU: NVN-4003489
MPN: 18-5187
UPC: 808282113018
Technical specifications
| Brand | Sierra Engine Parts |
| Model | Sierra 18-5187 |
| SKU / MFR# | 4003489 |
Set product metafields under specs.* to populate this table.
Frequently asked questions
No questions yet. Got one? Drop us a line.
