Engine - Sodium Filled Valve Handling Precautions

SAFE HANDLING OF SODIUM FILLED VALVES

Sodium filled exhaust valves were introduced in all 2004 model year 2.5L DOHC engines. Sodium has a high thermal conductivity and liquefies at high temperatures. Once liquefied it moves within the valve to promote faster cooling of the valve head by transferring heat to the valve stem.

When working on Subaru engines with sodium filled valves, take a few moments to review the cautions listed in the Subaru service manual for safe handling. Sodium is a highly alkaline and very reactive substance that will react severely when exposed to moisture. Never attempt to disassemble these valves as injury may result. Valves that are damaged due to accidents or other sources of engine damage may expose the sodium they contain to the atmosphere. In these cases appropriate handling of these valves is require to prevent personal injury or property damage. The Subaru service manual outlines these precautions in depth. This information can be found quickly using STIS and searching for "sodium within the appropriate service manual. Disposal requirements for damaged valves are also discussed. Always comply with all applicable local, state, and federal laws and regulations when disposing of these parts.