Mercedes Sprinter Coolant Expansion Tank Cap – Hudson | Screw-On Type | #0005018215 (NCV3 & VS30)

DESCRIPTION:

A leaking or failed coolant expansion tank cap is one of the most overlooked causes of coolant loss on a Sprinter — and one of the cheapest fixes. The cap maintains system pressure, allows coolant to expand safely as temperatures rise, and seals the reservoir between service intervals. When it fails to hold pressure, the cooling system operates below spec, coolant boils at a lower temperature, and you lose fluid without an obvious leak anywhere in the system. This Hudson replacement screw-on expansion tank cap restores proper pressure regulation across NCV3 and VS30 Sprinter models.

What This Part Does

The coolant expansion tank cap contains a two-way pressure valve — a pressure relief valve that opens when system pressure exceeds the rated threshold (typically 1.4 bar on these applications), and a vacuum valve that allows coolant to return to the reservoir as the engine cools. Together they maintain a stable, pressurized cooling circuit that raises the boiling point of the coolant and ensures consistent coolant level over time. A cap that no longer holds pressure causes the system to vent coolant prematurely, leading to gradual coolant loss and elevated operating temperatures.

Screw-On Type — Verify Your Cap Style

This is the threaded screw-on type cap. Some Mercedes-Benz applications use a twist-tab cap with a different sealing mechanism. Always verify your existing cap style before ordering — the two types are not interchangeable.

When to Replace

Replace if your Sprinter is losing coolant with no visible external leak, if the cap seal is cracked or deformed, or as part of any cooling system service or expansion tank replacement. This is a low-cost preventive item worth replacing any time the cooling system is being serviced.

Fitment

• 2010–2018 Mercedes-Benz Sprinter 2500/3500 – All Engines (NCV3)
• 2019–2024 Mercedes-Benz Sprinter 2500/3500 – All Engines (VS30)
• 2007–2009 Dodge Sprinter 2500/3500 – All Engines

Always verify your cap style and VIN before ordering. Contact us and we'll confirm fitment before you buy.

Part Numbers

• Mercedes OEM: 0005018215 / A0005018215 / 000-501-82-15
• Hudson: 66100
• Cross Reference: 2105010715, 2105010615, 2105010515, 2105010315
• SKU: 0005018215H