NISSAN 21430-C991A Radiator Filler Cap (Non-Vented)

The genuine NISSAN 21430-C991A radiator cap (fixed, non-vented design) is designed to securely and hermetically seal the vehicle's cooling system. This premium genuine part (CAP ASSY-FILLER) is engineered specifically for cooling circuits where pressure regulation is handled not by the filler neck cap itself, but by a separate pressure valve unit located elsewhere in the system.

Technical Specifications and References:

• Manufacturer: NISSAN (Genuine OEM part)
• OEM Part Number: 21430-C991A
• OEM / Replacement Part Numbers: 214301P107
• Type: Fixed sealing cap (non-vented design)
• Material: Durable, high-heat and chemical-resistant metal/plastic alloy with a specialized rubber gasket

Function and Importance of the Radiator Cap:

The non-vented radiator cap plays a crucial role in maintaining the integrity and seal of the cooling circuit. It prevents coolant leakage and evaporation through the filler opening, thereby contributing to maintaining optimal engine operating temperatures. The precise fit ensures that no loss of pressure occurs in the cooling system, which would otherwise lower the boiling point of the coolant and lead to engine overheating.

Signs of Failure or Wear:

• Traces of coolant or dried antifreeze residue around the rim of the cap.
• Visibly aged, cracked, or hardened internal rubber gasket.
• Unexplained loss of coolant from the cooling system.
• Mechanical damage, deformation of the cap, or worn locking tabs.