hi

i bought an audi a3, 2004, 2.0 tdi 6 months ago

the coolant level has always been going down slowly, id say i have to refill it every 3 weeks or so depending on how many miles i have done.

there is no visible leaks, either on radiator or on the floor.
it has been pressure tested and there is no sign that it is the head gasket as no oil or water is mixing.

my garage said it will be the EGR cooler, so i have replaced this at the cost of £450 and suprise surprise the coolant seems to be dropping again

at a loss as to what it could be??
when starting sometimes it starts up perfectly but on other occasions it can take me a couple of goes or stutters to start

anybody know what the next step could be to check???!!

thanks