Hi,

I'm losing my hair quickly with this problem.

My 51plate TDi 130 (AWX) has started to lose water, but there's no leaks.

Took it to a garage who pressure tested and, no surprise, they diagnosed a leaking water pump. Got them to change that & cambelt, but problem still not fixed. Took it back to them where they did another pressure test on 100% G12, but still no leaks. They test drove the car and said coolant was being blown out of the expansion tank.

They then did a block test which showed the head gasket was fine, so recommended that the thermostat be changed. I did this, but the problem is as bad as ever. I lost 5 litres of coolant yesterday in about 30 miles, so its definitely going somewhere.

The cooling system is pressurising, and when I undo the expansion cap to top it up, the pressure releases and some coolant makes it back into the tank.

There's no obvious sign of a head gasket leak - oil is good, no oil in coolant and no steam out of the exhaust. I'm at a real loss on this one, but I've already spent the best part of £500 on the problem, and I'm no further forward.

Help!?!?!?