RustyBucket

The chinese have documented the exact reason for the tensioner failure: http://club.autohome.com.cn/bbs/thread-c-772-22276482-1.html (if you're using google chrome browser, right click anywhere on the site and select translate to english): So what we see here is that the ratchet locking piece of metal has been worn down and so it fails to lock with the ratchets Drawn in red is the supposed shape the piece of metal is when new. (my artistic interpretation) The speculation is that when the engine starts to rattle, it is because of those few missing milimeters that put a bit of slack to the chain at the start of the engine, before the oil pressure puts tension on the piston. When this bit of metal finally fails completely, the whole piston is retracted which is too much slack on the chain and it jumps teeth. So its only speculation, that by the time 4 teeth are visible on the tensioner, this piece of metal has been eaten away to a certain degree when it's becoming unreliable. My assumption is that the degree of wear of that little piece of metal is more due to how many times the engine was started/stopped, or if it was left in gear parked on a hill, more than the amount of mileage. Hypothetically, if you drove 50k miles in one single drive, the chain would have stretched the same amount as if you would drive those 50k spread out in 1000 separate trips, with a 1000 loads on the ratcheting parts. The tensioner would have the same number of teeth visible, but the first one would have the ratcheting mechanism brand new, the other would be worn down. So the teeth visible can't be a sure indicator of how much the ratcheting parts are worn down... but it is an indicator if increased risk, and you can check it without removing the timing chain cover. I think this has been posted already, how you can see the number of teeth on the tensioner by removing the front passenger wheel, removing the wheel arch plastic cover, and removing the small plug as encircled on the photo below when you open it this is what you see If you want to DIY check it you have to lie under the lifted car to see this, so make sure it's jacked up safely and secured on stands etc. Even better have the mechanic check it when the car is already lifted when they change the oil. But again, the number of teeth can't be a sure indicator. In my opinion, when you start to hear a rattle, especially if it gets louder or longer lasting each time you start the engine, it's time to think about replacing the tensioner. Personally, if you have a lot of miles on the car (don't know, let's say more than 70-80k?) I'd replace the chain and guides as well.

Did you measure when the engine is warm? I measured after a drive and kept the engine running while i measured and it showed -2.60, i have a 35k 1.8tsi... The correlation is not direct, but the tensioner is supposed to be more at risk of failing after 4 teeth are exposed on its piston, which means the chain has stretched somewhat - how much can be seen with this vcds measurement. So you don't need to take apart the front right wheel arch and look through the hole in the cover (the plug on the hole is to be replaced with a new one once you remove it, supposedly) to see the tensioner directly. If vcds shows 0,00 then the tensioner shouldn't possibly have 4 teeth visible. From what I have gathered, if you only replace the tensioner, the chain will keep stretching (because it also isnt constructed so well which is why there is a newer revision available) which means that the engine has to compensate (thats what the block 93-3 measures) the difference to run optimally. So with a revised tensioner you make sure the chain will not skip and destroy the engine(which is what this topic is about), but the engine doesnt run as good(citation needed exactly how, and how relevant is this) with values less than lets say -3 and below as it does on 0,00, which is after you replace the tensioner as well as the chain (and guides). This is my understanding of things from various information, I am not a mechanic so take this with a grain of salt...

Do you mean it would slide back inside, even though the chain guide isn't pressing on it because the sleeve takes the pressure (I don't think the piston could retract into the housing by itself without the chain guide pushing on it), or that that the tension from the guide to the sleeve would cause the sleeve to jump out from around the piston (so the question would be what kind of sleeve would stay in place) I know this is something macgyver would pull out of his sleeve, but just maybe it could function at least as a temporary solution before commiting to invest in an expensive repair for a car that really hasn't got the miles for such expenses so soon... Btw, I found this russian forum with some good info on the subject, with help from google translate I think theres some useful bits which I don't think were mentioned here already... http://www.drive2.ru/l/3098586/ For instance, you can see how much the chain has stretched not only by physically inspecting the tensioner for how many teeth there are visible on the piston, but also by looking with VCDS, in the coding menu 01 Engine - Advanced meas. values - block 93 ... apparently, values -0 - -2 are okay, -2 - -4 conditionally ok, below -4 supposedly demand replacement. Also some extensive info on this russian autobild article, google translate makes it surprisingly readable http://autobild.by/index.php?id=3607

What do you guys think of this Macgyver-like solution of using the hole in the cover: http://www.golfmk6.com/forums/attachment.php?attachmentid=41169&d=1402505634 to put a spacer around the tensioner like this: http://www.golfmk6.com/forums/attachment.php?attachmentid=41171&d=1402505634 It would basically do (somewhat simplified) what the revised tensioner does; keep the piston from retracting back when the engine isn't running...