A-Premium Engine Coolant Overflow Recovery Reservoir Tank for BMW E46/E83/E53 2.2–3.0L — With Sensor & 30 PSI Cap

The A-Premium Engine Coolant Overflow Recovery Reservoir Tank is a direct-fit replacement reservoir with sensor and pressure cap engineered to restore proper coolant expansion and monitoring for compatible BMW models.

This replacement coolant overflow tank is molded from heat-resistant PA plastic and comes complete with a spring-loaded twist cap, pressure rating to 30 PSI, mounting hardware and an integrated sensor. It matches factory dimensions for many E46, X3 and X5 engines (2.2–3.0L DOHC 6-cylinder variants) and carries multiple reference numbers for easy cross-reference. The unit is packaged to simplify installation and backed by a one-year unlimited-mileage warranty for buyer confidence.

Will this reservoir fit my BMW E46, X3 or X5?

Compatibility covers a range of late-1990s to mid-2000s BMW 6-cylinder models. Verify your model year and engine size against the listed fitment to ensure a match. The part replaces several OEM reference numbers, easing lookup for spare parts catalogs.

• Fits E46 320i, 323Ci/323i, 325Ci/325i/325xi, 328Ci/328i, 330Ci/330i/330xi (1999–2006, 2.2–3.0L)
• Fits E83 X3 (2004–2010) 2.5L/3.0L and E53 X5 (2001–2006) 3.0L
• Cross-references: 17137787039, 17111436413, 17117573781, 17132247553, 603-535

How does this tank handle heat and pressure under normal driving?

The reservoir is built from durable PA plastic chosen for thermal resistance and vibration tolerance, and the supplied cap is spring-loaded with a maximum pressure rating of 30 PSI. That combination helps the cooling system maintain correct pressure and allows safe expansion and recovery of coolant during engine temperature changes.

• Material: heat-resistant PA plastic for long-term durability
• Cap: spring-loaded twist design, rated to 30 PSI
• Pressurized design supports coolant expansion and return cycles

What comes in the box and what are the physical dimensions?

This kit ships with the reservoir tank, a compatible sensor, a radiator cap, and a clamp for secure hose connection — ready for direct installation. The package dimensions reflect factory equivalence to ensure proper fit in the original mounting location.

• Included: 1 tank, 1 sensor, 1 cap, 1 clamp
• Mounting holes: 1; Height 359.7 mm, Length 121.3 mm, Width 133.4 mm
• Constructed to OEM-style mounting points and hose fittings

Will replacing the reservoir affect engine performance or emissions?

Replacing a cracked, leaking or non-sealing reservoir restores the closed cooling system’s ability to maintain correct coolant levels and pressure. While it doesn’t change engine tuning, a sound reservoir helps prevent coolant loss and overheating events that can indirectly affect efficiency and emissions over time.

• Restores correct coolant recovery and reduces risk of fluid loss
• Helps maintain system pressure for consistent engine temperature control
• Supports sensor function for accurate coolant-level monitoring

Who is this for: the A-Premium reservoir kit is aimed at BMW owners, independent mechanics and restoration specialists working on E46 series sedans/coupes and early X3/X5 SUVs with 6-cylinder engines who need a reliable, OE-style replacement. It's ideal for vehicles showing coolant leaks, cracked tanks, faulty sensor readings or missing/broken caps, and for anyone restoring the cooling system to proper working order without modifying factory mounting or plumbing.