Ratchet and/or spring clip are made of the correct material (hardness, chemistry, etc.) Ratchet and/or spring clip are made to the correct dimensions (ratchet too thin? spring clip the correct diameter? etc.) Compare to other failed tensioners (same tooth break? same tooth wear? etc.) Compare brand new tensioners from supplier (identify part to part variation) Identify Manufacturing trends (FOR EXAMPLE, all tensioners that failed were made between November 2009 and February 2010)

Hello MK6 forum.Long time lurker, and first time poster, but I think everyone here will find this interesting.I hopped in my car January 5, 2016 to head out to dinner, and my car would not start. 112,000 miles on the odometer, bone stock, and only other issue I've had is a cracked intake manifold (I'm on my 4th). Lo and behold after some diagnosis my timing chain tensioner had failed. Now some good references to this issue areand also. But what I'm going to cover here is the analysis of the actual failed part.A quick background for me: I'm an engineer at a competitor OEM and I work in Quality and focus exclusively on warranty parts. Every day I look at failed warranty parts, analyze them, and fix the root cause so it doesn't happen again. I wanted to get into this as I have yet to see any definitive breakdown of what is actually happening to this tensioner, and what the risk is to everyone else that owns a 2.0 TSI that has not yet had this issue (hint: prognosis is NOT GOOD)So here is the timing chain tensioner from my 2011 GTI (Part# 06H 109 467)If we rotate it 180° to look from the top:And slide this spring off:We find this little piece of metal in the hole. Look a ratchet!Now the problem I see here, is that there seems to be a tooth missing?? lets take a closer look (like, with a microscope):Yeah this does not look good. I can tell you that when this was still in my car, I could compress the tensioner and this "ratchet" was definitely not holding. Reference(note, this is not my video, but it is much clearer than the one I took of my engine)Lets look some more at the wear on these pieces. There is obviously some wear going on on the teeth of this little ratchet insert. You can see the root and the crest of the teeth are no longer parallel, and the leading tooth is broken:Top down same idea:And from the side you can see the differences in the angle of the tooth face. Anything less than 90° is not very good for holding tension:Now here is the wear on the back of the ratchet insert:And the wear on the inside of the spring clip:And finally the wear on the teeth of the tensioner piston:What seems to be happening is the wear is allowing the ratchet insert to slip vertically, gradually losing contact with the teeth. Ideally you have this instance where the teeth are all vertical and interface correctly (expert engineering drawings here):However, in this case with the wear, the teeth are allowed to slip and the ratchet piece now has more vertical playNow this is where I will have to make some educated guesses. I do not work for VW so I do not have access to drawings. I do not have an unused tensioner to compare this to. And most importantly, I do not have contact with the supplier for the chain tensioner. My next steps if I were actually solving this as one of my projects would be to verify the following;Now I do not have access to the specific failure data from VW, and some of the questions above will remain unanswered. However, all the questions above are directed towards manufacturing variability of the part. What we DO have is a wide array of anecdotal evidence around the interwebs that indicate this has been a problem endemic to Tiguans, Jettas, Passats, Beetles, and our beloved GTIs. We also know that VW has released a technical service bulletin (1512-01) that applies to ALL models built from 2008 to 2013. In my experience, an OEM would not apply a TSB if they did not suspect failure from a range of VINs, so we can safely deduce that this could happen to any 2.0 TSI engine built from 2008-2013. With this wide of a VIN range and the fact that VW is on theirrevision of the tensioner, we can safely assume towards a design flaw. Here is the application range for TSB 1512-01:So we have to decide between manufacturing variability, whereor a design flaw, which. I believe with the scope of the TSB and the quantity of design revisions VW has gone through, that this is a design flaw and this design cannot hold up for the life of the engine.I doubt that 5,000mi oil changes would reduce this wear (I changed oil every 10,000mi). The only thing I can see that would prevent this is to reduce the forces on the part and the quantity of duty cycles. What would constitute a duty cycle? Well anything that would put rotational force on your crankshaft without engine oil pressure; IE leaving your car in gear without using the parking brake, or starting the engine (Only one of these things you really have control over).Based on all the information I have available, namely my experience and my failed tensioner; this is not anfailure, its a. I would STRONGLY suggest that everyone with this iteration of the tensioner gets it replaced. The DIY I linked at the beginning of the post is very handy. Its a "quick" fix now or an expensive one later (I had piston/valve contact and am now looking to remove the head and replace valves).I know some people have gotten this replaced under warranty, but most people with these model year vehicles are now slipping out of the warranty period. Now all of these failures will be the responsibility of the vehicle owners. Its getting close to prime-time for a class-action lawsuit of some kind if all of my assumptions are correct (kinda wish I was a lawyer now...)Anyways, here's a final look at the part than can ruin your day and your engine!