John Elway

As the title states, is it avoidable through following the proper maintenance schedule? Or is it going to happen and it's just a matter of time?

LarryJa

It will happen in time. However, with timely, good oil maintenance/changes, that time may be at 200k miles. I just heard of a 4.2fsi that went 250k miles on all original chains & tensioners

raj99

Everything that moves can wear out and a timing chain can last a VERY long time, it really does depend on maintenance and a good amount of luck. The chain itself doesn't fail too often, but what will fail is items the chain depends on (i.e. guides).

KevinGary

I was the original owner of a 2005. I changed the oil every 5,000 miles and was meticulous with having it serviced at the dealer. Despite this care, the tensioners and the guides failed around 135k miles. These parts are made out of plastic and have a limited life expectancy. By the way, at 135k miles the chain had zero stretch.

jujuC6

Same here, my guides went 3yrs ago and chain was fine at the time ~130k. I have put around 45k miles after top guides were replaced with no signs of problems so far.

A6Gary

Even though the chain guides are a thermoplastic, they should last as long as the piston rings, valve guides, camshaft bearings, and main bearings, IMHO. If a primary engine part fails prematurely such as these guides, then I would maintain the part and/or the lubrication system is not designed properly to have the same design life as the other main engine parts. It would also appear that the majority of the failed guides discussed on the forums are the upper chain guides, which would indicated some other contributing condition leading to failure.

LarryJa

While the upper timing chain guides are a weak point on these engines, they seem to fail sooner if the relayed tensioners start losing oil "draining down" while the car sits, typically overnight. That's when we'll get the startup "clatter".
Once the startup clatter begins occurring, the upper chain guides get beat up & fail.
The tensioner leak down is caused by poor oil maintenance & subsequent tensioner wear.
Therefore, particularly attentive oil maintenance will support longer tensioner & guide life.
My '06 3.2 C6 (w/162k miles) has a steady 7.5 degrees of deviation on it's driver's side cam bank & half that on the passenger side. I've been motitoring it for the last 12k miles that I've owned the car. I have no startup clatter, at all.
I will also admit that I've already bought all the tools specifically needed to do an upper tensioner replacement. Someday, I will need to use them.
I just took a 1200 mile vacation trip with the car & had prepared to replace that bank 2 upper tensioner in a couple of weeks. However, since my vcds readings continue to be steady, I've postponed that repair for now. (Instead, I will be removing & having the intermittently faulting abs controller repaired)
So, in conclusion, I've seen that especially vigilant oil maintenance does prolong the life of these engines' upper timing chain tensioners & guides. That has been the collective wisdom on this forum for quite some time.
Their failure is fairly common, & because the 4.2's require engine removal for their replacement, I avoided buying a 4.2, which is what I originally lusted for. :-(

jujuC6

Good to know, thanks. What's the process with VAG to monitor the tensioners? Got 40k on my C7 and when it sits for more than 3 to 4 days it clatters very briefly at start up (⊙.☉) should I worry? On my C6 oil changes at around every 5k but it still happened to me like most of us here. I lean towards poor design as main cause.

beep-beep

Maybe it just my feeling, but I think the tentioners start loosing oil sooner if people drive off in the car right after starting up. Without giving engine a second to pump oil though the tentioners.

Otherwise it sounds like very reliably and simple way to deal with it: the chatter started - change tentioners. You do not have to warry about it the rest of the time.

LarryJa

Actually, I'm leaning toward it being a poor material choice for guides. Apparently, the plastic chosen for the guides is not durable enough for it's job.

In Ross Tech vcds,the engine module measuring block #93 provides the deviation, from ideal, for each of the four cams. You sum the readings of both cams in each bank. The readings are in degrees & the acceptable service limit is 8 degrees for each bank.

That should get you a start. :-)