1.6 TDI Coolant loss

Hello guys,

I've been having a problem with my A3. It's 2014 with a 1.6TDI engine. I've noticed coolant loss(about half an inch in the coolant reservoir) every 4-5 days. I took it to the Audi dealer and they can't find the problem.
First, they tested it for external leaks and couldn't find any. Then they checked the EGR cooler and no luck. Now they took of the engine head of and the head gasket and tested it, but the head is fine.
They saw residue of coolant in the engine oil.
What could be the source of the problem? Any help is appreciated.

Thank you.

if its not the head, head gasket? you can usually tell when you remove it, it could be block. the oil cooler is an easy suspect, oil will usually get out into coolant as well, at least its supposed to, so they say..

Oh lord. It's probably head lift. A simple inspection. For air bubbles and some arp head studs swap would probably have fixed it. Your in deep when you could have possibly been in the shallow end. Only solution now is to make sure the head and block are square and flat to the crank journals and put it back togeather and pray

I agree with the above mentioned oil cooler leak.