Coolant leak v6 3.0 tdi

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greenberry

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Hello!

I'm up against some real mechanical sorcery here.
I'm having coolant leak issues in the valley of my v6 tdi 3.0 (CDUC motorcode)

I've changed to new gaskets on the base plate of the oil cooler, both sides. I've also bought a new coolant flange with new gaskets and installed it.
Now to the real issue, I keep getting leaks when refilling coolant, same place.

I'm thinking it might be 059121737AM (Cooling System Bypass Line Adapter) housing. But reading on other people having the same issue, that's usually a very small leak. (new gasket is installed on the adapter, but not changed the adapter itself yet) When I refill the coolant it seems to fill the valley to a certain point kind of fast, but seems to stop after that.

Any ideas on how to continue from here?
 
Solved it. Seems theres a crack in the vent cover which leaks. Had to clean it all up and check carefully
 
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Ah okay, I'm back once again.
Backstory:
One day when leaving home in my A7, v6 tdi (cduc motor) I got an error message that coolant was low. Sure thing I thought, walked out and checked my expansion tank. It looked empty, put also very dirty with some sludge. Okay, I refilled it. Stuck my finger in there and pulled it out. Bang, we had an oily finger which immedietly gave me some bad vibes.

After that we had some weeks of changing parts, see below:


I've replaced almost everything in the valley and front of the engine.
Both top and bottom oil cooler gaskets.
Coolant Flange 059121506E (haven't done the Coolant Valve 059121737AM)
Replaced Water Pump
Replaced Oil Filter housing (thermostat is part of this)
Replaced front cover seal (https://www.ebay.co.uk/itm/393137643071?epid=249552177&hash=item5b88d45e3f:g:g9UAAOSwmbpgq6y5)
Replaced Cover in the valley of the engine 059103525F
Replaced Crank shaft seal (https://www.ebay.co.uk/itm/393273758192?epid=249068432&hash=item5b90f151f0:g:HSIAAOSwUNNgh~LJ)

PS. It's still building water in the valley of the engine, I've ordered the 059121737AM which might solve this issue.

But the annoying part of which I can't seem to find a reason is that I get oil in the coolant.(visible in the expansion tank, which was taken apart and washed while we changed the engine fluids)
But there's NO coolant escaping into the oil. Oil looks pristine and changed very recently (when changing the oil filter housing)


Could the actual Oil Cooler block be broken somehow? I need ideas here, anything appriciated.
Edit: Could it have been that we were sloppy with the cleaning of the coolant system when we first had the issue? Also, for the last 5k kms that i've owned it, it's never overheated
 
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