Upper Gearcase Seal SIERRA 18-2003

Compatibility Information

The SIERRA 18-2003 upper gearcase seal is a critical component ensuring the integrity of your propulsion system. Due to the absence of official manufacturer data listing compatible engine models, we cannot definitively specify which brands (e.g., Mercury, Yamaha) this part fits. We strongly recommend verifying compatibility by cross-referencing catalog number 18-2003 with the original equipment (OE) number provided in your engine's service manual. If you have any doubts regarding part selection, contact our customer support team to ensure you receive the correct equivalent that guarantees a watertight seal.

Installation and Maintenance

Proper replacement of the upper gearcase seal is vital for engine longevity. Before starting work, ensure the engine is turned off and cooled down. During disassembly, inspect the condition of sealing rings and the shaft to rule out mechanical damage. The new SIERRA 18-2003 seal should be installed with strict attention to cleanliness to prevent contaminants from entering the gearcase. After installation, we recommend checking for leaks before the first startup.

• SIERRA Original Quality – guarantees durability and resistance to harsh marine conditions.
• Precision Engineering – ensures a perfect fit and prevents oil leaks.
• Easy Replacement – a standard component that can be replaced during routine maintenance.
• Gearcase Protection – effectively isolates the propulsion system from water and debris.
• Catalog Number 18-2003 – facilitates accurate identification and ordering of the correct part.