RACINGLINE - Billet Header Tank Cap - MQB - 1.8 - 2.0 - EA888.3 - GOLF - VII - S3 - 8 - VWR19G703

The RacingLine Billet Coolant Expansion Tank Cap is a critical functional upgrade for your cooling system. While factory plastic caps can lose their ability to hold pressure over time, this meticulously engineered billet replacement ensures your high-performance engine maintains the exact pressure required for maximum cooling efficiency.

Key Performance Features

• Full Replacement: This is a complete engineered replacement for the OEM plastic cap, not a cheap stick-on cover.
• Pressure Management: Features a sophisticated internal springing and bleed-off mechanism to maintain perfect system pressure.
• CNC-Machined: Meticulously crafted from a solid billet of 6061 aerospace-grade aluminum using 5-axis technology.
• Signature Finish: Hand-polished and gloss-anodized in Midnight Black for a deep, long-lasting aesthetic.
• High-Temperature Durability: Designed to withstand extreme heat soak without warping or losing its seal.

Why Upgrade Your Cap?

A worn factory cap can lead to pressure loss, lowering the boiling point of your coolant and potentially causing overheating. The RacingLine cap ensures absolute tightness and safety, providing peace of mind for both daily and track use.

MQB / A5 Platforms

A direct replacement for almost all modern VW Group vehicles with the 5Q0121321 part number.

High Performance Tuning

Essential for modified engines where increased thermal demands put more stress on the cooling system.

Additional Enhancements

• Installation Service: Have your cooling system parts fitted by experts at MGM Leeds.
• Complementary Upgrades: This cap is part of the full billet engine bay range, including the RacingLine Billet Oil Cap and Washer Fluid Cap.

Compatibility & Applications

Compatible with a vast range of Audi, VW, SEAT, and Skoda models across the MQB and A5 platforms.