DavidA

hi! if it hesitates when cold > inspect intake manifold links x2 > they hold the flaps closed when cold// www.gruvenparts.com Atlanta GA has the metal links/parts for $90 for two (two lenghts) the vacuum pod is a Land Rover part for $80 @ LR dealers ??Audi wants $400 for the kit!!!
David

mishar

Intake manifold flaps are always opened if the links are broken. That causes a bit lower power under 4000 rpm. When working properly system closes flaps upon start and keeps them closed up to 4000+ rpm, than opens them for a different intake resonance and more power on high rpm.

domge

I knew if I kept looking I wd find someone with similar problem. I have EXACT same piece found floating around cyl 1 intake valve. I convinced myself the part was possibly dropped into intake by prev mechanic. I bought this 2007 S6 used. I installed same intake but now feel as though I better find a replacement. Thanks for your post and pictures.

MP4.2+6.0

Having dealt with this manifold on my 2000 A6 4.2, it's problematic over the life of the vehicle. I know this is an old thread, but since it has come back a few times I thought I would post to it with some recent experience perhaps relevant to the life of a D3 4.2. Kind of sobering.

I pulled a head for the second time on my 2000 A6 4.2 to deal with an oil burning issue before I sold it to family. As in, 13 years on the road, 147,000 miles. Ultimately I found a damaged cylinder wall very low down in the cylinder at the scraper ring area in the cylinder I always knew had the issue from a plug that would could two or three times a year. I can't explain how that cylinder wall issue happened, but the damage was there and not fixable without a new block or a rebore. Nonetheless, I did manage to tweak some things that seem to have moved oil consumption down meaningfully, even returning to more rational viscosities than I had been nursing it with for the last few years. Not the focus of this post though.

I bolted it all back up cleanly and replaced a lot of wear parts along the way--various hoses, a broken torque mount, wire clips, new timing and serp. belt (since they had to come off anyway to pull head), etc. But at the last major part to go back in--the intake--I found the flaps both frozen and jammed. But neither set of diaphragms had torn, nor were the plastic links broken. Hence why I didn't notice the problems when I pulled it even though it was sitting for a week as I got other parts in hand and did the rest of the work.

When I diagnosed it further I found it frozen at the front seal area on each side. I had also pulled the manifold three years ago for the same oil burning issue at an earlier stage. At that time I found the mechanism stiff but movable. I cleaned and lubricated it as best I could. It was better so I reassembled it into the car during the preceding motor job. This time I was not so lucky. Having poked around the net and having seen the posts off and on for years now on the C5 A6 board about broken front links, I know my issue is not only not unique but perhaps more ominously more along the lines of a fairly likely scenario at higher miles and years.

Ultimately the shaft components were not removable from the intake. The front components are pot metal and you can't reliably put the necessary force on them to extract the front of the shaft assembly and get at where the seal and binding issue is. As in, I view the repeated posts about broken links diaphragm issues and the like as ultimately "symptoms;" the crux of the binding is where the ultimate problem arises and then manifests itself in broken parts at the front of the manifold where the vacuum switching happens. With a broken manifold I searched all of eBay, and then e mailed and followed up with basically every wrecking yard listing them on car-parts.com for my part #. About a dozen all in. In the end, not one had a functional one, let alone at a given decent price. Either they got sold with the motor or loose, were damaged, or had similar issues to mine. Net, basically none available on the used market. That includes searches out to eBay UK and eBay Germany. Yes, only at one spot time in the market, but it is a fully aged car, and higher volume than D3's. It also crossed over to the D2 for the relevant couple of years, but still no dice.

So, my sober conclusions are this part is likely to fail in the 10-12 year, 100-150K mile timeframe. And, lubrication ultimately didn't keep it going, even though I caught it a couple years earlier before anything broke. I am also in sunny California, and while the car got Tahoe winter use, in general it lived in a well above average environment climactically and was garaged probably ⅔'rds of its years.

I ended up having to buy a replacement manifold via a dealer for big bucks, even with a discount. Literally the most expensive service Audi part I have ever bought, putting aside the ZF rebuilt 5 speed tranny for the same car. Only because I had fixed everything else (that was fixable) and was ready to sell to the brother in law did I go through with buying it. Unfortunately this experience, the timing belt service and some other things caused me to come to the conclusion that the motor really is long term obsolete. Nice in its time and I enjoyed the ride and (for its time) power, but like its product use as an N.A. belt driven V8, I watched it fade away as the brother in law drove it off with a smile on his face and 300HP and the full torque curve back under foot. Presumably the blown nature of the 4.0T (or 3.0T) eliminates the whole intake flap contraption, and all the current motors seem to have gotten back to various (complex) chain drives. Audi calls it Art in Engineering. Goldberg has other names.

dvs_dave

The newer turbo motors are way more complex and have much more very expensive stuff to go wrong in comparison to the old NA 4.2.

In a few years time, the cost of replacing sticky inlet flaps will pale into insignificance compared to the ruinous time bomb problems that are inevitable with turbo motors.