Description

This Valve Stem Seal Set is a premium replacement component designed for heavy-duty diesel engines using OEM part numbers 3921640 and 3904303 . Valve stem seals play a critical role in controlling oil flow to the valve guides, preventing excess oil from entering the combustion chamber while maintaining proper valve lubrication. Manufactured from high-temperature, oil-resistant elastomer materials , these valve seals are engineered to withstand constant heat, pressure, and chemical exposure found in diesel engines. Proper valve seal performance helps reduce oil consumption, minimize exhaust smoke, and protect internal engine components from premature wear. This 8-piece valve seal set is ideal for upper gasket set service, cylinder head rebuilds, and valve train maintenance , restoring factory oil control and sealing performance. Precision-molded to OEM specifications, these seals ensure correct fitment and long-lasting reliability. Key Benefits: OEM replacement for 3921640 / 3904303 Controls oil flow to valve guides Reduces oil consumption and exhaust smoke High-temperature and oil-resistant construction Ideal for upper gasket sets and head rebuilds Designed for heavy-duty diesel engine applications