Well, as I’ve now completed a full timing chain component rebuild using the identical part to JHM’s “Full Plus OEM Kit”
- I live in England so purchased all of the parts listed in JHM’s “Full Plus Kit - OEM” locally from Audi, the only reason I did this was due to the high import duty I would have had to pay the UK tax man when importing JHM’s kit - But for anyone else not in the UK I would purchase from JHM as their kit is great value and contains all the parts you need to ensure you end up with a rattle free engine).
I decided to look at each part of the timing components to try and identify which were the problem components, purely from a physical wear point of view. I will start by showing the parts that appear to be the most problematic and add a few each day. All off these components where remove from my 89k (Miles) late 2005 B6 S4 that has a FULL Audi Service History and had been on Long Life Servicing for it’s first three years.
The most problematic appears to be :
1. The Left Lower Guide Rail - Audi Part Number 079109469AA - Located between the left idle gear and crankshaft on the main timing chain.
- This is the guide that we see cracked in many of the rebuild threads and also JHM state that many timing chain overhauls they have done, they have found this guide to have failed (cracked) allowing a slackness of the chain… So was mine.
http://i18.photobucket.com/albums/b118/jimgreen72/IMG_22891_zps0d9be2c5.jpg
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The depth of the groove that the timing chain had worn into the guide, was 1.5mm (I am not sure how deep the groove is on a new item though, so unable to establish if this is near to the maximum or has work as expected.
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I can only guess the reason that these items fail (Crack) is probably something to do with design or materiel failure.
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I believe the part number for this item has remained the same - Suggesting that maybe this part has not been revised, but will wait one of the experts to confirm this or not.
PART 2 TO FOLLOW SOON.