Intake Manifold - Broken Links

[Sir WIll]

Ladies & Gents,

A lot of threads and wisdom on this matter has been covered in this forum and other internet locations. I even hijacked a thread myself about this fault as I have had this exact problem with the car recently.

Therefore I wanted to start a brand new thread on the fault, assumptions and repair route I went to resolve. I am not suggesting this is the way everyone should repair their own car but only my approach for resolution.

This is how I resolved the problem and I have used some information found from the wise people on the A8 Parts Forum as part of this post.

Fault: Engine Light ON

Result: VAGCOM Scan showed a P0174 OBD-II Trouble Code "Bank too Lean" (Could also be 171 for the other bank), secondly I had a hesitation on the throttle around 4000 rpm when driving and finally MPG was a little down

Assumption: Air leak in the system, crank case vent valve broken, Air intake manifold bellows link broken

Inspection Result: Checked all the pipes for damage or leaks and all were in good condition and intact, I did replace the Crank case vent valve as a matter of due course but it was not the fault (077103245B). Looking at the two intake manifold bellows and their links, one was broken as shown below. They are made of plastic and the heat over time I assume makes them brittle. Though you must ensure the sprung loaded arm that is moved by the bellow and link is functional and can move freely. If its jammed, sticky or gets stuck there is likely to be another problem and the link broke due to this. Therefore move with your hand to check that it operates OK.



Repair Action: The replacement from Audi comes as a complete kit including the bellows and links for £150 to £200. Its way over the top and so long as the bellows are OK you do not need to replace them. The part is also similar to one on a Land Rover and a Lamborghini (VAG family V10). But even so its way to much money.

Now GruvenParts.com do some very high quality replacements that look bomb proof and beautiful. But they are $89 plus $35 postage which again is too high for a 1" link (There is also a 2" version for other VAG engines so check the ones you have first before doing anything!).

I used eBay to source new ball joints and threaded bar so could make my own version at home for a little over £10 a link.

M5x0.8 RIGHT HAND THREAD GREY NYLON LINKAGE BALL JOINT
http://www.ebay.co.uk/itm/1312634601...%3AMEBIDX%3AIT

M5 12mm GRUB SCREW
http://www.ebay.co.uk/itm/2212477688...%3AMEBIDX%3AIT

Now I could not find any linkages that were short enough out the packet so you need to be prepared to cut them down and do a little work for the result.

The ball joints have an 8mm cup size and a M5 Thread on them. Out the packet below they are 33mm in length which is too long for the replacement.



Remember to order Left hand or Right hand so they will thread Ok on the M5 grub screw.



I used a vice and a hacksaw and cut them down to 19mm. Its a little fiddly to do but was OK in the end. If you can find short ball links then this may be a better option. These are also nylon but seem stronger that the OEM versions but again you may want to go with metal if you so choose.

I then screwed approx. 6mm of the 12mm M4 bar into each, applied a little thread lock and put some electrical tape round them to tidy things up.

An there you have it a replacement link for much cheaper than other options.



It will not win any beauty contests but it should prove functional.

To replace on the car take some pliers to unclip the old broken parts and then clip on the replacement part.

Clear the codes and drive away. Though of course after a couple of hundred miles double check everything is OK and still good with the links.