Overflowing Expansion Tank Cars affected: Evo 4-6.5 (possibly earlier Evo's and the Evo 7) Symptom: Coolant leaks out around the Expansion tank filler cap. Problem and cure: This is a very common problem and really is a quirk rather than a fault. It will occur after a period of hard driving after the coolant has been topped up or changed. The cap does not seal very effectively and coolant can leak out around it rather than go down the drain pipe. The correct coolant level, when cold, is approximately 10mm-20mm above the 'Min' level. If the coolant continually drops below the minimum point and doesn't settle at a specific level then it could indicate a coolant leak somewhere in the system and will require further checks. Approximate cost of repair: N/A Back to question page