Keep your outboard motor running smoothly with the Sierra 18-2659 seal, a reliable aftermarket replacement for the OMC 396355 crankshaft seal. Designed for marine enthusiasts who demand durability in harsh saltwater and freshwater environments, this high-quality seal prevents oil leaks, protects internal components from contaminants, and extends the life of your engine. Whether you’re restoring a classic Johnson or Evinrude or maintaining a workhorse boat, this seal delivers OEM-level performance without the premium price tag.
Key Features and Benefits
Precision Engineering: Crafted from premium nitrile rubber and metal construction to withstand high pressures, temperatures up to 250°F, and constant vibration—common challenges in outboard applications.
Perfect Fit Guarantee: Matches the exact dimensions and tolerances of the original OMC 396355, ensuring seamless installation without modifications.
Superior Sealing: Lip design with integrated spring provides dynamic sealing, reducing the risk of leaks that can lead to overheating or catastrophic engine failure.
Corrosion Resistance: Ideal for marine use, resisting saltwater corrosion and fuel contaminants better than generic alternatives.
Cost-Effective Maintenance: Replaces multiple OMC part numbers, saving time and money during routine servicing or rebuilds.
Compatibility with Johnson and Evinrude Engines
This Sierra 18-2659 seal fits a wide range of OMC outboard models, particularly V4 and V6 engines from the 1970s through the 1990s. Commonly used in:
Johnson/Evinrude 115-150 HP models (various years)
V4 crossflow engines
Select V6 powerheads
Always cross-reference with your engine’s service manual for exact fitment, as lower unit configurations can vary. Pro tip: Inspect the mating crankshaft surface for scoring during replacement—light polishing with emery cloth can restore a perfect seal surface and prevent premature wear.
Installation Tips for Long-Lasting Performance
Replacing your crankshaft seal is a straightforward DIY job with the right tools, but attention to detail makes all the difference:
Prep Work: Drain the oil and remove the powerhead or lower unit as required. Clean all surfaces thoroughly to remove old sealant residue.
Seal Driver Tool: Use a seal installer or socket that matches the seal’s outer diameter to avoid cocking during press-in.
Lubrication: Lightly coat the seal lip with engine oil before installation—never use grease, as it can swell the material.
Torque Specs: Follow factory torque values for housing bolts to prevent distortion.
Break-In: Run the engine at low RPMs for the first 30 minutes post-install to allow proper seating.
Common pitfalls? Over-tightening or reusing old gaskets—both lead to leaks. If you’re dealing with a scored crank, consider a speedi-sleeve for an instant fix without machining.
Why Seals Fail and How to Spot Trouble Early
Crankshaft seals wear out from age, dry starts, or contaminated oil. Watch for these red flags:
Milkshake-like oil in the water (emulsified coolant intrusion)
Low oil pressure warnings
Blue smoke from the exhaust on startup
Oil spots under the lower unit after trailering
Regular oil analysis every 100 hours can catch issues before they sideline your boat. Pairing this seal with fresh Yamalube or Quicksilver oil keeps things humming season after season.
Frequently Asked Questions
What does the Sierra 18-2659 seal replace?
It directly replaces OMC part number 396355 and is compatible with various Johnson and Evinrude outboard crankshaft applications.
