Hi can anyone please help I have a 2002 Galaxy 1.9TDI which has covered nearly 100,000 miles when I bought the car about a 1.5 years ago I had the timing belt , water pump and thermostat replaced all was well untill about 5 months i noticed that there was water around the expansion cap so I replaced the cap on the bottle but still the poroblem there. The enginge does not overheat the temp gauge sits at 90 all the time. I park the car overnite on the drive and cheak the water when cold and I can see that the water has dropped to the min mark but as i undo the pressure cap the water rises and a load hissing noice occurs. Can Anyone please help with this problem