Ok, for anyone who saw my thread on the coolant issues in a 3.0 it's still going on. Everything checked out fine so I broke down and took it to the dealer.

Master/Head whatever Audi mechanic is stumped. They left it on a pressure tester over night and didn't leak a drop. Drove it a mile up the road and it started pouring out - clearly a heat issue, but can't pinpoint it.

They've had it for 5 days and already charged me 300 just in looking. Stopped by today and its torn down to the point they can't even make it run. They want 1,800 dollars to go even deeper and just replace everything it could be because they can't find the problem. 2,100 dollars and no promises it won't leak. What could possibly be that deep in the engine to cause an external link? Especially since its leaking on the REAR.

So far I'v told them if they find any crack in the block to instantly stop work, but also that if they fix this, any leak in the future- labor and parts is 100% on them

 

There is one easy way, find someone with a smokemachine

Empty out the coolant, fill it up with smoke and check if you can find the leak.
(Dont start the car though! )

 

For anyone interested the cause has been found. Anyone endlessly searching and arguing with people that its not the crossover pipe should read.

Apparently, according to the dealer, there is a smaller pipe running underneath the intake manifold connecting to the crossover pipe. That pipe had a hairline crack on the bottom side, so even with the entire manifold removed you'd never see it unless you traced the dye.

2300 dollars later.

 

Just picked it up, not happy at all. Can't even see the crack, they even had the nerve to mark up the price of coolant to 34.56 even though I showed them a receipt from a week earlier, from there own parts department where it was 27.

Coolant cross over pipe and "Metal coolant hose" were the big hitters
06c-121-085-H
06C-121-188-B
06C-121-075-F
034-145-779-D
4B0-121-107-B
N-909-125-01
1.49 "Service history administration fee"

Various other seals and small rubber hoses etc. On the plus side I went out and drove like a madman - not a drop leaked, no overheating nothing.

But I'v cancelled all plans of trading in this B6 commuter car for an A8 W12 primary car.