coolant lose A3 2.0 TDI

Nov 10, 2017
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Hi everyone

i've got a audi A3 2.0l TDI (8pa) 2005 (103 KW/140 HP) BKD engine 6 speed triptronic gearbox.

For the last year I've had a constant coolant lose it goes down slowly and only on journeys 100 miles +no loss at all on small journeys, no overheating and no visible leaks, passes pressure test and sniff test, no smell of coolant inside car,no mayo on dipstick and coolant looks clean. so far I've changed -

Radiator (signs of leaking)
EGR cooler (was advised they can leak internally)
Coolant temp sensor housing (signs of leaking)
Expansion tank cap

i'm going to change the water pump soon is there anything else i could check as i love my A3 any advise would be greatly appreciated.

Have you checked the coolant bottle as they sometimes have a slight crack in it and not very noticeable to the eye , feel around and see if you feel anything out off the ordinary.
Check your cylinder head revision (A, B or C). It is stamped on the head itself. If A, I assume you probably know where I am going with this.
That’s what i didn’t want to hear Rideen lol I know it’s possible for the head to be cracked and if I do end up hv ing to replace the head I’ll make sure it’s a C revision :thumbs up: was just hoping to get some advice on alternate possible causes before the big 1
I totally understand you mate, I went through it all a few years back. Replaced everything that could cause the leak and in the end removed the cylinder head and I had a crack to see. :(
Was there any other signs apart from the coolant loss Rideen ? I’ve had 3 different mechanics all reassure me that it’s not the head

I’ve ordered a new expansion tank going to replace that (still living in hope) lol I’ll update this thread soon as it’s done
I had probably dozen of mechanics tell me it's not the head. Other symptoms would sometimes include a puff of white smoke on cold start and if I'd leave car standing for 2-3 days after a long journey (so the coolant was pressurised completely before turning the car off), I'd have odd startup.

The coolant loss was only noticable on long journeys where it would have enough time to pressurize and leak into the cylinder. Short journeys did not seem to cause any leaks.
I was having odd start up’s now and then, but after a new battery it hasn’t since, I’ll keep an eye for white smoke on cold start your story sounds exsacally the same as mine
Hi everyone
been looking into new cylinder head C revision, and come across a post saying -

"Current cylinder head is 03G 103 308 B which is one of the possible porous/cracked heads.
I've not been able to find the 03G 103 308 C on ETKA myself, only able to find the 03G 103 351 B which is for the BKD. (the rev. E is for the 6 speed manual, rev. B is for the DSG)"

i'm assuming from the above that i already have the rev. B head as mine is - 03G 103 351 B
can anyone confirm this ?
if i need to change the head id like to put the C revision if possible part number would be great thanks :sos: