Hello all...new to this forum...I have a mechanics garage in Concord Ca and the shop next to me is having a heck of a time with a 2.7 A6. They have replaced the timing belt and the tensioner (4th) and if they drive it for 6-10 miles the tensioner comes loose (lost tension) and it jumps a tooth sometimes even. Sounds like a diesel when it comes back in. They have pulled it apart many many times and reset the belt/tensioner everytime and end up with the same results. thye do have the cam alignment tools and the crank tool as well.
This is just something we have never seen and neither has the local Audi dealership. We are looking for suggestions or help from anyone that has come across a similar issue.

Thanks!

Ted's Automotive
Concord, Ca

 

It may be as simple as replacing the bolt, since I would believe they torque the one in to the right specs.
I don't think they're torque-to-yield, since the manual is mute about it (nothing along the "always replace" lines), but with bolts you never know. Maybe it was stripped when they removed the old tensioner. And since they used the same bolt over and over again several times, probably it doesn't hold the torque anymore.
Other than that, I don't see any other reason for it to lose its tension (unless it is a spring-loaded model and the spring is defective).

Of course, they can use thread lock high strength and let it cure good, but the bolts are cheap.

 

I had the same problem. It turned out that the tensioner that came with my
TB kit was a cheap no-name knock off. It did'nt have enough pressure to keep the
belt tight. I believe that I replaced it with an NTN and everything was perfect after that. Luckily my belt did'nt jump and the valves were fine.

Hope this helps,

Ron

 

new tensioner is direct from Audi, however i think that the belt may have stretched a bit from slapping the w/p housing.

Any more ideas? if we find anything else in the meantime I will let you know.

thanks for the replies thus far.

 

Did they pretension the tensioner? Should be 15 Nm pretensioned with the cam gears loose.

 

Is there any adjustment on a 2.7 tensioner? My 2000 2.7 was a sealed damper/tensioner. Once it's installed you pull the factory pin and the tension is applied.
Is is possible that the Audi tensioner is defective? Can the plunger rod be pushed back in
very easily... that's what mine did. The belt would lose tension after a short drive and
I could hear the engine rattle each time. I went through 2 new tensioners and bought a
different brand tensioner for my 3rd teardown on the TB assembly. Good Luck.

Ron

 

So you guys actually talk about the "shock type" damper tensioner.

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And I only had in mind all this time the tensioner roller.

Probably my "bolt" suggestion raised a few eyebrows, as in "WTF is he talking about? He hasn't a clue"
Is there a chance that this one got installed in an "untensioned" position?

 

You are supposed to pretension it to 15Nm with a torque wrench, once the belt is on, cam gears loosened and the pin pulled. That perhaps was the reason that you had all the issues?

 

Thanks for the info on the pretensioning hxgaser. Are those specs found in a service manual such as Bentley.. just curious for next time around.

Thanks,
Ron

 

Yes the manual shows the spec.