NISSAN 21712-50M01 Coolant Reservoir Tank Cap

The genuine Nissan 21712-50M01 coolant reservoir tank cap is a premium quality, non-pressurized plastic closure designed for the cooling system expansion tank. This genuine OEM part ensures a perfect fit and reliable operation.

Function and Operating Principle

The primary function of the non-pressurized coolant reservoir cap is to tightly seal the expansion tank. This prevents coolant evaporation, splashing into the engine compartment, and protects the cooling circuit from external contaminants (dust, mud, and other foreign debris). Since this type does not incorporate a pressure relief valve, its purpose is to maintain atmospheric pressure within the tank while providing dependable physical protection.

Technical Characteristics and Specifications

• Manufacturer: NISSAN (Genuine OEM part)
• Part Number: 21712-50M01
• Part Type: Coolant Reservoir Cap (non-pressurized)
• Material: High heat- and chemical-resistant plastic composite capable of withstanding extreme engine bay temperature cycles and the chemical components of coolant.
• Design: Threaded or snap-on closure with an ergonomic shape for effortless opening and closing.

Signs of Wear and Failure

Plastic components can lose their flexibility over time as a result of continuous thermal stress and natural aging. Replacement of the cap is recommended upon observing any of the following symptoms:

• Visible cracks, deformation, or fractures on the plastic body.
• Wear on the threads or latching mechanism, preventing the cap from seating securely.
• Increased coolant evaporation or signs of leakage around the reservoir neck.
• Ingress of foreign contaminants (dust, soot) inside the expansion tank due to inadequate sealing.