uxcell Radiator Filler Neck for Toyota Sienna & Lexus RX350 2007-2010 — Sealed Metal Cap, Mounting Bracket

The uxcell upper radiator filler neck is a direct-fit replacement radiator coolant inlet with a fully sealed metal cap designed to restore proper coolant flow and pressure for compatible Toyota Sienna (2007–2010) and Lexus RX350 (2007–2009) models.

If your vehicle is exhibiting overheating symptoms, steam near the radiator neck, or coolant loss, a worn or cracked filler neck and an ineffective cap are common causes. This uxcell assembly pairs a durable plastic neck with a reliable metal-sealed cap and bracket so you can replace the worn component with a single, ready-to-install kit. It is manufactured to match OE numbers 16431-31490 and 16401-62100, so fitment must be confirmed against your vehicle’s part reference before purchase.

How does this filler neck restore correct cooling system performance?

Replacing a degraded filler neck and cap re-establishes the coolant pathway and the system’s pressure seal. That helps the cooling system maintain the intended boiling point and prevents air ingestion that can cause hotspots. The kit arrives complete with the neck, a matching metal cap, and the mounting bracket for a straightforward swap.

• Replaces OE numbers 16431-31490 / 16401-62100 for correct fit.
• Sealed metal cap maintains proper system pressure.
• Plastic neck body resists typical road-heat and coolant exposure.
• Includes bracket for secure mounting and alignment.

Will this part fit my Toyota Sienna or Lexus RX350?

This component fits specific model-year and engine combinations listed by the manufacturer. It is intended for Toyota Sienna CE/LE/XLE 3.5L V6 (2007–2010) and Lexus RX350 Base 3.5L V6 (2007–2009). It does not fit certain sport or non-standard configurations—always verify year, trim, and OE number before ordering.

• Compatible: Toyota Sienna 2007–2010 with 3.5L V6 (CE/LE/XLE where specified).
• Compatible: Lexus RX350 Base 2007–2009 with 3.5L V6.
• Not compatible: some RX350 sport or other non-base trims and specific Sienna LE variants—check part numbers.
• Confirm vehicle VIN/part reference for exact match.

What materials and design features improve durability?

The neck uses automotive-grade plastic engineered to withstand coolant chemistry and engine-bay temperatures, while the cap uses metal with the correct spring pressure rating. Together they reduce the risk of cracking, warping, and cap failure that can cause pressure loss and overheating.

• Plastic neck body resists heat and coolant exposure for long service life.
• Metal cap provides consistent sealing pressure and corrosion resistance.
• Factory-style mating surface ensures a tight seal to the radiator/reservoir.
• Included bracket secures the assembly and preserves alignment under vibration.

How easy is installation and what comes in the package?

The kit is designed for a typical DIY replacement or professional install with basic hand tools. You’ll get the neck, metal filler cap, and the mounting bracket so you won’t need to source additional parts for the swap. Follow torque specs and cooling-system bleeding procedures recommended by the vehicle maker.

• Package includes 1x coolant thermostat housing water pipe / filler neck.
• Includes 1x matching engine radiator filler neck metal cap.
• Includes 1x mounting bracket for secure installation.
• Recommended: replace coolant and bleed system after install per manufacturer guidance.

Who is this for: This uxcell radiator filler neck assembly is intended for owners, DIY mechanics, and repair shops working on Toyota Sienna (2007–2010) and Lexus RX350 (2007–2009) vehicles who need an OE-referenced replacement part to address coolant loss, overheating symptoms, or a damaged filler neck. It’s especially useful when you want a complete neck-and-cap kit with a bracket for straightforward installation—just confirm your vehicle’s model, trim, year, and OE number before purchasing.