Product: Expansion Tank Cap (Water Bottle Radiator Cap) Key benefits Restores and maintains correct coolant system pressure to reduce overheating and coolant loss. Creates a secure, leakresistant seal for the radiator coolant overflow recovery tank. Durable plastic construction in black for a neat, OEMstyle appearance and long service life. What it does Seals the vehicle's coolant overflow recovery tank (water bottle radiator) to maintain system pressure and prevent coolant leakage. Acts as a directfit replacement part to restore proper cooling system performance after cap failure, loss, or damage. Important attributes Function: Expansion tank / radiator coolant overflow recovery cap — seals and regulates pressure in the overflow reservoir. Placement: Designed specifically for the vehicle water bottle radiator (coolant overflow recovery tank). Material: Plastic for corrosion resistance and reliable sealing. Color: Black, blends with the engine bay and original equipment. Compatibility: Direct replacement for OEM part numbers 1640153010, 1640175120, 1647528120, and 16475. Why customers need it A faulty or loose expansion tank cap allows coolant to escape or causes improper pressure, which can lead to overheating, reduced heater performance, and potential engine damage. Replacing the cap restores correct pressure control and prevents coolant loss. Performance and fit Engineered to match OEM fit and function for the listed part numbers, providing a precise, secure seal with minimal installation effort. Typical use scenarios Routine maintenance: an old or worn expansion tank cap during scheduled coolant system service to maintain pressure and prevent future leaks. Post replacement: Install a cap after repairing or replacing the coolant overflow tank or hoses to ensure a proper seal. Emergency replacement: Swap in this cap if the original cap is lost, cracked, or failing to stop visible leaks or overheating warnings. Installation notes Simple, tool replacement on most vehicles that use the specified OEM part numbers. Inspect the tank neck and seal area for damage and clean before installing for results. Reference part numbers OEM fit for: 1640153010, 1640175120, 1647528120, and 16475. Compatibility and safety Confirm compatibility with your vehicle by matching OEM part numbers listed above before . when signs of wear, cracking, or pressure loss are observed.