Coolant loss

[Harri]

Any ideas on cause of coolant loss - expansion tank and cap been replaced; pressure test no leaks; no spill under car: heater works (but not great) : not overheating and no other obvious problem - 2 garages now stumped as to what it could be. 

One suggestion was intercooler but 2nd garage said unlikely and at 1000£ replacement, I'd just like to know for sure the right thing gets fixed! 2014 A3 tdi 2litre. Having cam belt and water pump replaced in next few weeks also. 

[Stevey Y]

3 hours ago, Harri said:

Any ideas on cause of coolant loss - expansion tank and cap been replaced; pressure test no leaks; no spill under car: heater works (but not great) : not overheating and no other obvious problem - 2 garages now stumped as to what it could be. 

One suggestion was intercooler but 2nd garage said unlikely and at 1000£ replacement, I'd just like to know for sure the right thing gets fixed! 2014 A3 tdi 2litre. Having cam belt and water pump replaced in next few weeks also. 

Hi it could be part of the heater matrix has collapsed so it might be leaking inside the car so you won't see it, check for moisture under carpets where they run along front bulkhead and above pedal box, if it was the oil cooler you would see water in the oil or oil in the header tank which manifests itself as little black dots in the coolant.

 

Steve.