So I got a leak the other day that started making a whistle from the engine compartment when the car gets into boost. I had made a pvc fitting to go in the turbo inlet pipe and hooked it up to the compressor at 10psi. I can hear air escaping from the back of the motor somewhere of which I first thought was the 3 way breather hose (06B 103 221)so I took that off and the rubber was so soft on the back downside that I put a hole in it instantly. Got a new part and installed, but that wasn't my main culprit as I can still hear air escaping from somewhere around the bottom or below this hose. I am having a hard time feeling it and locating it. Is there another common fail point back there or maybe trick I can use to be able to see where it is leaking?

 

Yes, under the intake there is a breather tube.
http://www.ecstuning.com/Audi-B5_A4-...ssions/ES5942/

It's a common fail part and if the symptoms are as you described, then it's almost certain that this part is the culprit. With age it crumbles very easy. To replace the T hose that you replaced, you have to disconnect that hose from this breather tube. In doing so you may have cracked it. Not your fault, it happened to me as well. It just crumbled when I touched it, it could have happened to you. My cylinder head was off when it happened to me so I was able to see it crumble, you may not have if your intake was on.

It's as simple as pulling the clip off and pulling it out.

 

The back downward fitting of the breather I replaced looks like it fits over and clamped to a hardpipe that continues to go further down below the intake. Does the hard pipe go bad or are you saying there is another rubber piece below the hardpipe that fails? I couldn't see very much down there maybe i'll have to take off the intake manifold to inspect some more.

 

It isn't easy to see, but you can get the tube off without pulling the intake manifold. There is also the hose you mentioned (the 3rd hose we haven't mentioned that would go into the T hose you replace), but that, I think, is a far less likely culprit.

The breather tube goes bad and just cracks everywhere. Once you have it out, you'll see why. It's too pieces put together and "plastic welded" leaving a bunch of room for splitting. There is also a seal where it goes into the engine that could have shredded.

You will want to pull the 3 screws out that hold down the coolant tank and move that out of the way. Once you do you should be able to finnagle your way down there and loosen that T hose clamp holding the tube, and also easily remove the clip that holds it down.

 

This is slightly different from my 98 but it's the same process and part, it just has a different design.

This guy put together a good video

 

Mine was very similar to the youtube video and must be a little different than the part you led me to on ECS website. I was able to get to it all by propping the coolant reservoir out of the way. Starting at the bottom of the hardpipe piece that comes down from the breather hose (06B 103 221) that I originally mentioned in the first post, there is a T fitting (058 103 247). Another side of the T goes to the L shaped hardpipe (06A 103 213) that connects into the crankcase with spring clip and has O ring on it. The 3rd side of the T goes to a slightly S shaped piece of tubing (058 103 221) that goes up to the cluster of vacuum lines/components on top of the intake manifold. I found that the S shaped piece of tubing had a 1" slit in it and was looking very soft and worn out in general. I removed it as one with the T and L shaped hardpipe, which also broke where it goes into the engine. The only thing that I question is that I didn't think I heard the boost leak coming from where I found the tear, but I am going to get all three of these parts from Audi today and hope it clears my problem. One thing I would mention to be careful with is to check if your hardpipe breaks off because the pieces that broke off mine ended up falling down into the engine and took me some time rigging up vacuum sections to get them out.

Thank you for pointing me in this direction and hopefully this may help someone else. Just to mention my car is a 2001 AWM engine code.

 

UPDATE: This did not fix all of my problem as after completing this I still had a very noticeable whine when in boost that sounded like a dentist drill and I believed was my turbo going bad. Yesterday I ordered a K04 center cartridge from G-Pop Shop and today when I took out the airbox I hooked up the air to the turbo inlet pipe and noticed that there was still a leak at the back of the motor. From what I can tell there is some sort of sensor below the three way crankcase breather hose right behind the valve cover. This sensor piece looks to be bolted in and there is also an aluminum piece that has 3 torx bolts going down vertical into it. After spraying some soapy water and feeling around more, it appears there is quite a leak right below or at the bottom of this sensor area.

Any help on what this is and what might be leaking here?

 

I took off the sensor (C271300702) and there is a half circle shaped cutout in the engine housing that my thumb just fits into. I believe this is where air is leaking. Does anyone know what this is and how to attack it? I'm assuming the valve cover has to come off and there is something inside. I didn't look that closely yet but i'm also guessing the head gasket is down lower than this..

 

Looks like the problem is a cam chain tensioner gasket. There is a half moon rubber seal and a metal gasket roughly 5" long. I'm hoping this is causing the dentist drill whine and that my turbo is actually fine.