Originally Posted by JohnLZ7W

I was getting alot of oil build up below the intake manifold and some prodding around uncovered two boost leaks as well. The car has 107k miles on it so I figured I should probably rebuild the entire PCV path instead of just replacing the torn hoses.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2301.jpg">

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2306.jpg">

Parts that I used are listed below. There are a couple other hoses and valves that can be replaced. I inspected mine and decided they were ok so I left them for now.
Also, and more importantly, these are AMU specific. If you don't have an AMU engine or aren't sure check with your dealer first! And of course, Audi did change things along the way so what I found on my car (early build MY2001 with ESP) might not be the same on yours.
I sourced all of these through my local dealer, Sunset Audi in Portland. I had sworn off giving them anymore money after a couple of issues I had but they were great to work with this time.

06A-103-213-F
N-904-673-01
06A-103-247
035-103-245-A
058-133-753-B
06A-133-783-AS
06A-133-783-AT
06A-133-783-BA
06A-133-789
058-129-717-D
06A-103-663B-SJ - dipstick tube
assorted small hose clamps
alot of brake clean

I started out bench assembling everything, making sure I had all the parts and of course hose clamps for everything.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2251_small.jpg">

Not seen in this picture are N-904-673-01 which is an o-ring, and 035-103-245-A which is the actual valve and is located inside the T-housing.

You can see that the assembly attaches to the car at five spots, the big 90^ fitting, the other side of the T-fitting that holds the PCV valve, the U bend at the left of the intake manifold and the small 90^ that goes into the bottom of the intake manifold.

Total time to do the swap was about 4hrs. Brad (GoKart3) assisted and it's always helpful to have a second set of hands while doing anything like this. Also, I wanted to do this without removing the intake manifold. I thought it would be possible, and it was, but I think if I had the factory rubber hoses for the small vacuum lines and not the uprated silicone hoses it would have been harder. YMMV, it might just be easier for you to pull the intake manifold, if you go that route make sure you have the necessary manifold gasket(s).

Start by removing the front engine covers and the trim piece in front of the intake manifold. Oh, you'll also want to have the car in the air and the belly tray removed, you will drop stuff

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2257.jpg">

Next remove the mounting plate that supports the dipstick tube. This is held in by two 5mm allen bolts. Alot of this teardown will look familiar if you've done an engine speed sensor swap

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2258.jpg">

I should note here that you will want to have a spare dipstick tube on hand. We weren't very far into this when mine snapped at the base. This is pretty common when working on high mileage cars so be ready for it ahead of time. It's cheap insurance.

Getting the plate out of the way clears room to get to everything else that has to be removed. Here you can see the red silicone lines that I've used in place of the factory rubber plumbing.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2259.jpg">

There's an electronic controlled valve on the bottom of the plate that needs to be removed so the plate can be swung completely out of the way.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2260.jpg">

Once under the manifold you'll see three plugs on a metal mounting bracket. That mounting bracket needs to go in order to get the assortment of hoses in and out. Unplug the cables first, note where each one plugs in so you can get them all back where they belong. We needed to do some gentle prying on the catches to get them to pop free. That's the suction jet directly over the plugs.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2291.jpg">

The plugs will slide up out of the mounting bracket and now you're ready for one of the suckier parts of the install. The mounting bracket for those plugs is held in by a 6mm allen bolt and a regular 10mm bolt. The 6mm bolt is in a crappy location and I couldn't get to it from above so I had to use a regular 6-mm L-shaped allen key to slowly remove it. Oh yeah, right at the left edge of this picture you can see a rubber glove covering the remnants of the dipstick tube. It's easier to have the tube out of the way through all of this anyway.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2286.jpg">

On the left side of the bracket there's the 10mm bolt. If you wiggle the bracket with the 6mm bolt out you'll feel where it pivots, it's hard to see it though. Here it is highlighted. To the right you can see the 6mm allen half out.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2290.jpg">

With all of that out of the way there's lots of room to work. See how nasty it's gotten in there? I think that's a couple quarts of oil cooked down.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2265.jpg">

We used I think four cans of brake clean spraying everything down. Try to get it as clean as possible before removing the old parts. Easier to work and less chance of dropping some nasty crud down an important orifice. I highly recommend this stuff

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2270.jpg">

Ok so now that it's cleaned up and there's room to work you can disconnect the fittings to get the old parts out. As I noted above there are five attach points. Undo the hose clamps on the underside and left side of the manifold. Slide the clip out of the large 90^ fitting seen in the picture below.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2272.jpg">

The remaining fitting on the right side of the T-housing has a one-time crimp clamp that you can't easily get to. Fortunately it is attached to a pipe that hooks into the bottom of the black pancake valve attached to the valve cover. You can remove it at that end and slide it out with everything else. This makes reassembly easier anyway. Here you can see where the clamp is removed. Make sure you have a replacement.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2266.jpg">

In fact, to get everything reassembled it's easier to have the pancake valve loose too so go ahead and release the spring clamp that holds that too.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2271.jpg">

There's a 5mm allen bolt holding the metal pipe to the side of the engine. If you trace down the pipe a bit from where it attaches at the pancake valve you'll see it. With a long extension it's easy to get to.

That should be it. Slide the old assembly out from under the intake manifold. It will want to get caught on everything, especially the bracket that supports the right side of the intake manifold. Take note of how the pipe that runs up to the black pancake valve is routed, it needs to go back thru there.

When you take the old parts out make sure to get the old o-ring out of where that large 90^ pipe attaches.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2278.jpg">

Here's the old parts with the new shiny. You can see the extra metal pipe here on the right side of the old parts. The tab where the 5mm allen goes thru is also visible. Pop that off, clean it out thoroughly and put it on the new T-housing. This is a good time to get everything mostly lined up on the new parts to match the angles of the old parts. They do make this a bit easier because the fittings on the T-housing will pivot even after the hose clamps are tightened. Get everything tight here since you won't be able to get to most of it once it's installed.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2275.jpg">

Also put the new o-ring on the 90^ fitting prior to inserting it.

<img src="http://lz7w.com/albums/pcvcircuit/IMG_2280.jpg">

Reassembly is basically just the reverse. Be patient and get the new assembly back into place. Feed the metal pipe up the side of the block and get the tab attached to the engine, keep it loose for now just so it holds it in place. Slide the large 90^ fitting back into place taking care to keep the o-ring on. It'll take a bit of force to seat it. Make sure it makes it all the way in and that the clip makes it over top of the ridge on the outside of the fitting. It's easy to think you've got it right when you don't. In this pic it's not quite there.
<img src="http://lz7w.com/albums/pcvcircuit/IMG_2284.jpg">

Attach the hose clamps to the three remaining hoses, two on the left side of the manifold and the one under the manifold. Get the cable bracket back in place, put the 6mm allen and 10mm bolt back in and tight. You can also tighten that 5mm on the hard pipe to the pancake valve now. get the plugs back into the bracket and plugged back in. Once we had all of that taken care of we fixed the dipstick tube. There are other writeups for that so I won't cover it here. It sucks.
Reattach the electronic valve and vacuum lines under the metal plate at the front of the manifold and bold the plate back in place and you should be all set. Make sure everything is tightened back up put it on the ground and you should be set to fire it up and check or leaks and do a test drive.