Sierra 18-5807 Solenoid - OMC Sterndrive/Cobra

Why Choose the Sierra 18-5807 Solenoid for Your OMC Sterndrive or Cobra?

Boat owners know the frustration of a finicky starter that leaves you stranded at the dock or mid-water. The Sierra 18-5807 solenoid steps in as a reliable fix, engineered specifically for OMC sterndrive and Cobra systems. This isn't just any replacement part—it's built to match the original specs while delivering enhanced durability against the harsh marine environment.

Crafted from high-quality copper windings and robust housing, it handles the electrical demands of cranking your engine without hesitation. Whether you're dealing with intermittent starting issues, clicking sounds, or complete no-start scenarios, swapping in this solenoid often resolves the problem without breaking the bank on dealer parts.

Key Features That Set It Apart

• Direct OEM Replacement: Meets or exceeds OMC specifications for seamless integration—no modifications needed.
• Corrosion-Resistant Design: Marine-grade materials shrug off saltwater spray, humidity, and vibration for years of service.
• High-Torque Performance: Delivers powerful engagement to spin your starter motor reliably, even in cold starts.
• Universal Fit for Cobra Models: Compatible across various OMC sterndrives from the late '70s through the '90s, including popular 3.0L and V8 setups.
• Easy Diagnostics: Common failure signs like weak cranking or solenoid chatter make it straightforward to identify when replacement is due.

Perfect Compatibility for Your Boat

This solenoid shines in OMC Stringer and Cobra sterndrive applications, fitting engines like the 250, 270, 305, 350, and 400 series. It's a go-to for boaters with Bayliner, Four Winns, or other brands powered by these legendary powerplants. Always cross-check your engine serial number against OMC service manuals to confirm, but it's a staple replacement for models facing starter woes after decades on the water.

Pro tip: If your boat has been sitting through winter, test the solenoid first by jumping the terminals—quick confirmation before tearing into the starter assembly.

Simple Installation Steps for DIY Boaters

Replacing a solenoid is a weekend warrior project that takes under an hour with basic tools. Here's a straightforward guide:

1. Disconnect the battery to avoid sparks—safety first.
2. Locate the solenoid on the starter housing (usually inner fender well or engine block).
3. Unbolt the mounting bracket (two nuts typically) and disconnect the heavy battery cable, ignition wire, and starter lead.
4. Transfer any ground straps if present, then bolt in the new Sierra unit using the existing hardware.
5. Reconnect everything, check for tight connections, and fire it up.

Bonus: Clean corroded terminals during install for optimal performance. If you're new to this, grab a Haynes or Seloc manual for exploded diagrams specific to your model.

Extend Its Life with Smart Maintenance

To keep your solenoid humming season after season:

• Inspect wiring annually for frays or green corrosion—replace as needed.
• Use dielectric grease on terminals to repel moisture.
• Avoid short jumps or excessive key cycles, which heat up the coil prematurely.
• Pair with a fresh battery; weak voltage forces the solenoid to work overtime.

Many owners report this part outlasting the original by double the time, thanks to Sierra's quality control.

Frequently Asked Questions

Real Boater Stories and Tips

One salty captain shared how his '85 Cobalt wouldn't turn over after a rainy haul-out. The Sierra solenoid fixed it instantly, and it's been solid through three seasons of Lake Michigan chop. Another tip from forums: If your battery holds charge but starts weak, check solenoid heat—prolonged cranking overheats it fast.

Investing in quality like the 18-5807 means fewer headaches and more time on the water. Ready to get your sterndrive firing on all cylinders?