NISSAN 21741-VC200 Coolant Reservoir Hose

The Nissan 21741-VC200 genuine OEM coolant reservoir hose (HOSE-RESERVE) is an essential component of the vehicle's cooling system. This specialized hose connects the radiator to the expansion tank (coolant reservoir), ensuring bidirectional coolant flow during thermal expansion cycles.

Function and Operating Principle

As the engine operates, the coolant heats up and expands. Due to the resulting pressure, excess coolant flows through this hose into the reservoir tank. When the engine shuts off and cools down, a vacuum is created within the system, drawing the necessary amount of fluid back into the primary cooling circuit through the same hose. This process is critical for maintaining stable cooling system pressure and preventing the formation of harmful air pockets.

Technical Specifications and Material Composition

• Manufacturer: NISSAN (Original Equipment Manufacturer)
• Part Number: 21741-VC200
• Material: Premium-grade, multi-layer EPDM (ethylene propylene diene monomer) rubber with synthetic fiber reinforcement for maximum tensile strength.
• Resistance: Exceptional resistance to high temperatures, cooling system pressure, and glycol-based antifreeze additives.
• Design: Precision pre-formed factory geometry for a tension-free fit and proper clearance around engine bay components.

Signs of Wear and Importance of Replacement

Rubber components degrade over time due to continuous thermal cycling and environmental exposure. The most common symptoms of failure include:

• Visibly identifiable hairline cracks, hardening, or softening of the hose wall.
• Leaks or coolant residue around hose clamp connections.
• A steady drop in coolant level within the reservoir tank.

Replacing a damaged or aged hose is critical, as sudden coolant loss can lead to engine overheating and catastrophic engine block damage.