Evinrude & Johnson Lower Unit

Start with the complete engine model and serial number. Then confirm the existing gearcase family, original gear ratio, shaft configuration, rotation, bullet or case design and any OE or gearcase number. Horsepower and model year can narrow the search, but they do not confirm fitment by themselves.

The current products are presented as new aftermarket SEI Marine replacement gearcases, not genuine Evinrude or Johnson OEM assemblies. Condition must still be shown on each product page. If remanufactured units are added later, their rebuilder, core requirements, replaced components and warranty should be listed separately.

The ratio determines the relationship between engine speed and propeller-shaft speed. The current families include 2.0:1, 2.25:1, 1.83:1 and 1.85:1 configurations. A housing that appears similar is not automatically interchangeable, so confirm the original application and ratio before ordering.

Possible signs include abnormal gearcase noise, difficulty shifting, loss of propeller drive, lubricant leakage, water-contaminated lubricant or excessive metal in the drained lubricant. These symptoms do not identify the required replacement model. Stop operating the engine if serious damage is suspected and have the gearcase inspected.

Verify the rotation of the existing gearcase and propeller rather than choosing by port or starboard engine position alone. SE308 and SE318 are counter-rotation units, but they belong to different case families and use different ratios.

Follow the engine operator’s guide for flushing, corrosion inspection, anode inspection, lubricant and storage procedures. Inspect the gearcase finish and address exposed metal promptly. Service requirements can differ by model and operating conditions, so do not rely on one universal interval.

SEI’s current policy lists a three-year fault-free warranty for its outboard lower units, subject to exclusions, claim deadlines, freight responsibilities and other terms. Confirm product eligibility and review the exact manufacturer and seller warranty before purchase. Commercial and racing use are among the exclusions in the current policy.

Testing should follow the applicable service procedure and specifications for the exact gearcase. There is no safe universal pressure value for every Johnson or Evinrude lower unit. Have a qualified marine technician perform the required pressure and vacuum checks when appropriate.

Use the lubricant type and service procedure specified in the operator or service guide for the exact engine and gearcase. Official Evinrude guides provide model-specific lubricant and maintenance information, so avoid applying one interval or lubricant specification to every engine.

Depending on the SEI family and engine model, the upper driveshaft, water pump, shift shaft, propeller thrust washer or water-intake screens may be required separately or reused. Confirm all application notes before installation and use a qualified marine technician when the correct procedure or adjustment is uncertain.