Audi A6 2.4 petrol coolant problems

[mike_1985]

I got a small/big problem with my audi . Bassicly what happens afetr I drive the car for longer than 10 miles the coolant starts to boil . It doesnt show any messages or faults on the dash at all and the engine temperature stays at a normal 90c .

Any ideas what this could be ? Someone said to remove the thermostat and take it for a drive and dismiss that .

Any ideas ?

The car is a 2003 audi a6 avant 2.4 v6 auto petrol with 44k miles on the clock .