A4 1.8t Coolant leak
 

I have seen some discussions on a fitting at the rear of the engine leaking on 1.8t's. I have a leak on the rear of the engine and am wondering if a new fitting is required or an o-ring or does it just need to be tightened? Tough to see exactly where and what is leaking and thought I would ask before ripping into it.

its such a pain in the ass you might as well replace everything. if the coolant flange isnt leaking yet it will. took me 7 hours to do my coolant flange and now there is a needle nose pliers wedged somewhere on the side of my engine that i cant get to without removing a million parts.

coolant leak
 

I guess I will start taking stuff apart and replace parts as I go. That is how I usually end up doing it. I'll let you know if I find any secrets on the way.

I am doing the same right now. You may want to look over these two threads that have helped me out so far...
DIY Flange
Coolant leak @ Flange

I have an 04' 1.8t and I could not believe the many write-ups out there that are so different to my application. Sucks to look over the wrong one that makes it seem so easy, when this is honestly one of the most frustrating auto jobs I have ever done!!!

Agreed. I had the same problem with my AEB engine, and it was a real PITA. Honestly, just order the whole flange if you find out that the problem. The flange I got from ECS tuning came with the right size O-ring embedded in the flange. The real bitch is getting the two screws tightened just right so as to not leak after installation.

Definitely take a look at the DIY threads first. They'll give at least the direction needed.
If you are going for the coolant flange, take out all "vacuum stuff" on top. I skinned many knuckles trying to work around them, and in the end had to remove the canisters to reinstall the flange.
And in the end the plastic coupling feeding the heater core had also corroded/broke off..
But fixing it yourself does give a real sense of ownership and pride...

Yeah, this is something that most of the DIY's do not tell you! Most of them make it sound like an easy job and do not pass along the info of taking all these vac lines out of the way. Much like yours MTS, I broke the breather tube and then had to find a DIY on how to fix that (after much searching just to find out what tube it was). Bottom line is after this job and past work on this PITA Audi, I now have an 04 Audi 1.8t Quattro for sale!!!! lol

No REALLY, I am selling it and the flange replace DID have a little to do with it.

A4 1.8t Coolant leak
 

Definitely not prepared for this. Went in from the passenger side and didn't see what I needed so I went in from the driver side and still can't see what I need. I am going to button it up, add some coolant:),get some parts ordered and try it again once I am prepared to spend the time doing it right.

And if your REALLY lucky the coil pack wiring harness will short out after you finish the flange! It does give a little more room to disconnect the harness and pull it up and out of the way. Only if the sheathing covering the wires are corroded and crack, the bare copper will touch and short. Causing fuse 29 to blow!. I've read a thread of this happening...and it did for me too..
I got a thread going about this experience in the general tech area (b6 cranking only).
Best of luck to ya!

My started leaking massively earlier this week. After reading all of the horror stories of what a PITA it is, and given my limited amount of time due to stuff going on at work, I decided to have it done. $30 part. $600 labor. Ouch, but, done.

-Chris