Warning to ATL / TDI90 Owners - Please read.

dj_efk

A2OC Donor
United-Kingdom
Please read this post in my blog thread, and also this one below it - I’ve uncovered a design flaw in the design of the alloy lower boost pipe bracket / clip, in that thanks to engine vibrations / movement it gradually wears a hole into the alloy pipe - which is unique to the ATL and now obsolete from Audi and very scarce secondhand - the only source of a new one I found available at the time of writing is paying £150+ to someone in Europe, and heaven knows what you then have to pay in shipping and import duty etc.

I’ve cured mine of this issue by luckily finding a good used pipe (albeit one that showed the beginnings of the same issue developing) and by deleting the bracket / clip altogether. I would strongly recommend you do the same the next time you have your under-tray off as a preventative measure.

@Special edition Dave you mentioned a conversation you had with WOM about this, could you kindly chip in with what they said? Also how do we make this post easily found going forward? I fear as our cars rack up the miles and the part gets even scarcer, this issue is going to become more and more of a problem.
 
Last edited:
I spoke to Rob last week who said that 90% + of Tdi 90,s suffer from this bracket being broken. I think Marcus simply adjusts the position of the pipe to avoid wear. My car is currently in for some TLC at WOM and I will be asking them to consider removing this bracket in the morning. Thankyou for the heads up on this...you may have saved me some expense on the intercooler pipe. ?
 
Last edited:
@Erlingtheyounger just now raised the question of whether the removal of the bracket could allow extra stress through vibration to then be transferred to the intercooler, which as we know also has inherent weaknesses / design flaws. Personally when I checked with the engine running I think as there is now effectively the complete run of pipe available all the way up to the turbo to take up the engine’s vibrations, I doubt an otherwise-healthy intercooler would be compromised in this way.

EDIT: Thinking about it some more, this mod may even REDUCE stress on the IC and hence prolong its working life, because as standard you only have one medium length rubber pipe to absorb the vibration from the engine from where it is rigidly fixed to the sump via the clip in question. Hence the clip-delete may make even more sense as a mod to consider for all the diesels, due to the full run of pipe now being available to act as a dampener as above.

In Audrey’s case one of the @timmus all-alloy intercoolers are fitted so it would anyway not be an issue, but I’m going to do the same mod the Akoya which as far as I know has an OE intercooler (@PaulA2 can you confirm?) and I’m not worried in this regard.
 
Last edited:
Yes I agree the first aluminium boost pipe after the turbo does eventually get worn through by the plastic bracket. I think the reason is (as has been mentioned) the plastic bracket tends to break in some manner and ends up rubbing on the pipe in a manner it was not intended to. A couple of solutions I have employed with my TDI90's:

Careful application of some sort of chemical metal / epoxy filler works to fill any hole. If the inside of the pipe is stuffed to stop the filler encroaching into the pipe then the outside of the pipe can be built up quite thick. This then protects the aluminium from further erosion. Indeed, anyone worried about this could add a layer of epoxy to the wear area thus preventing (slowing down) the problem.

I have utilised the two original screws that hold the plastic bracket to the sump in a different manner. I have fastened a bar of aluminium to the side of the sump with a space behind and used a couple of wide zip ties to secure the pipe in its correct position. To avoid the zip ties wearing through the pipe I covered it in a bit of old rubber inner tube. The rubber also helps the zip ties grip the pipe thereby reducing movement and erosion.

Hope that helps somebody.

Trevor
 
@Erlingtheyounger just now raised the question of whether the removal of the bracket could allow extra stress through vibration then being transferred to the intercooler, which as we know also has inherent weaknesses through design flaws. Personally when I checked with the engine running I think as there is now effectively the complete run of pipe available all the way up to the turbo to take up the engine’s vibrations, I doubt an otherwise-healthy intercooler would be compromised in this way.

In Audrey’s case one of the @timmus all-alloy intercoolers are fitted so it would anyway not be an issue, but I’m going to do the same mod the Akoya which as far as I know has an OE intercooler (@PaulA2 can you confirm?) and I’m not worried in this regard.
I discussed the very issue of all alloy intercoolers with @Paul a2 when I purchased Tonka from him so would be 99.99% it has the standard intercooler sir.
 
Yes I agree the first aluminium boost pipe after the turbo does eventually get worn through by the plastic bracket. I think the reason is (as has been mentioned) the plastic bracket tends to break in some manner and ends up rubbing on the pipe in a manner it was not intended to. A couple of solutions I have employed with my TDI90's:

Careful application of some sort of chemical metal / epoxy filler works to fill any hole. If the inside of the pipe is stuffed to stop the filler encroaching into the pipe then the outside of the pipe can be built up quite thick. This then protects the aluminium from further erosion. Indeed, anyone worried about this could add a layer of epoxy to the wear area thus preventing (slowing down) the problem.

I have utilised the two original screws that hold the plastic bracket to the sump in a different manner. I have fastened a bar of aluminium to the side of the sump with a space behind and used a couple of wide zip ties to secure the pipe in its correct position. To avoid the zip ties wearing through the pipe I covered it in a bit of old rubber inner tube. The rubber also helps the zip ties grip the pipe thereby reducing movement and erosion.

Hope that helps somebody.

Trevor
Thanks Trevor, what’s interesting is if you read my blog post the clip was actually found to be fully intact and as it should be, so I don’t think the wear on the pipe is caused by clip breakage.

Your mod with cable ties and a rubber tube sounds to be to be the way to go if you want to correct the design flaw but not delete the clamp altogether.
 
Yes I agree. Even with an unbroken clip this pipe wear is common. I think it is because the original (design flawed) clip doesn't grip the pipe tight enough thus allowing movement under vibration and subsequent wear. A bit of inner tube between pipe and original clip could prevent this.

Trevor
 
As a Tdi 75 owner, the question I have is why the 90 has an alloy pipe in this position - can the equivalent from the 75 not be used in its place to eliminate this issue? Is it a different diameter, or is there another good reason for this?
 
As a Tdi 75 owner, the question I have is why the 90 has an alloy pipe in this position - can the equivalent from the 75 not be used in its place to eliminate this issue? Is it a different diameter, or is there another good reason for this?
Two good questions, as far as I know nobody has tried, but I think it was @timmus who mentioned it should theoretically be possible to swap in a rubber TDi75 item at least as a temporary measure.

If this is the case then I have no idea why the alloy pipe was specified on TDi90s, I assume there is a reason however.
 
Good question. I don't have a 75 so can't answer that. I do know (from experience) that the plastic inlet pipe from the air mass meter to the turbo is not interchangeable between 75's and 90's. Maybe the boost outlet is also in a slightly different position......not sure.

Trevor
 
Please read this post in my blog thread, and also this one below it - I’ve uncovered a design flaw in the design of the alloy lower boost pipe bracket / clip, in that thanks to engine vibrations / movement it gradually wears a hole into the alloy pipe - which is unique to the ATL and now obsolete from Audi and very scarce secondhand - the only source of a new one I found available at the time of writing is paying £150+ to someone in Europe, and heaven knows what you then have to pay in shipping and import duty etc.

I’ve cured mine of this issue by luckily finding a good used pipe (albeit one that showed the beginnings of the same issue developing) and by deleting the bracket / clip altogether. I would strongly recommend you do the same the next time you have your under-tray off as a preventative measure.

@Special edition Dave you mentioned a conversation you had with WOM about this, could you kindly chip in with what they said? Also how do we make this post easily found going forward? I fear as our cars rack up the miles and the part gets even scarcer, this issue is going to become more and more of a problem.
If you send it to me I’ll look at a fix for us
 
If anyone wants they pipe welded. I'm happy to help
Terry if you have the facility to do this then I would like to take you up on that offer please so as to ensure I don’t need to throw my old pipe away. Chemical metal would be an alternative option but would never be as good.

Let me know the details by reply to my PM. Thank you!
 
Hi George - do you mean the pipe? Let me investigate Terry’s offer first. I sure this must (will) be an issue for others so all opinions on a fix would be useful for the purposes of arriving at a generally-accepted fix!
No problem, I would cut out the affected section and sleeve it with Silicone hose
 
Two good questions, as far as I know nobody has tried, but I think it was @timmus who mentioned it should theoretically be possible to swap in a rubber TDi75 item at least as a temporary measure.

If this is the case then I have no idea why the alloy pipe was specified on TDi90s, I assume there is a reason however.
I have had the TDI75 plastic pipe (it is actually aluminium with a plastic casing on it IIRC) on my remapped TDI90 for some years and 50k plus miles. No adverse effects, leaks or bursts.
 
Back
Top