Coolant Expansion Tank / Overflow Bottle 603-027 For VW Jetta MK4, Audi TT, Seat Leon (1999-2006)

About This Product

Is the plastic coolant overflow tank in your VW or Audi cracked, leaking, or looking yellow and brittle? This is a direct replacement tank, part number 603-027 (also replaces OEM numbers like 1J0121407F). It fits a range of popular VW Group cars from around 1999 to 2006, including the Volkswagen Golf/Jetta MK4 (1.8T, VR6), Audi TT (8N), and the first-generation Seat Leon. The plastic on these tanks is known to get weak with age and heat cycles, leading to coolant loss and overheating. Swapping it out is a pretty straightforward DIY job – usually just a couple of hoses and a mounting screw or two. This one is brand new from Founders Advanced Products and comes with a 1-year warranty. Getting a new tank is cheap insurance against being stranded with an overheated engine. Make sure to use the correct coolant mix when you refill the system. A very common and sensible repair for these cars.