91302-PNA-004 Chain Case O-Ring - Overview. The 91302-PNA-004 Chain Case O-Ring is a critical rubber seal used in Honda marine engine systems. It supports the timing and lubrication system by sealing the chain case to prevent oil leaks, which is essential for maintaining proper engine lubrication and smooth operation. Engineered to precise factory specifications, this genuine OEM part ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features.