Timing Belt Tensioner Problems After Replacement

Hello everyone,
I have a problem, or rather, I'm confused. I replaced the timing belt, tensioner, and related components at a mileage of 271,000 km. When tightening the belt, I adjusted the tensioner so that the indicator was directly above the mark and securely fastened. I've now driven over 1500 km, and today I checked the belt. Unfortunately, I noticed that the indicator on the tensioner is no longer exactly above the mark; it's about 2 mm off. What does this mean? Is this normal, or do I need to readjust the tensioner? How can the tensioner have loosened? I tightened the screw properly to 20 Nm.

Thank you and best regards.
Reuselkopp.

I don't think the screw came loose. Rather, after making the adjustments, you should have turned the motor 2-3 times and then possibly adjusted the tension.
However, it is also possible for a new timing belt to become properly seated after a short break-in period.
For safety's sake, I would now double-check the valve timing and, if necessary, readjust or tighten it.

Hello RedR32,

After tightening the belt, I had run the engine twice, and everything seemed fine then. I can also imagine that the belt might have settled a bit, as it was quite stiff to begin with. To be clear from the start, this was a Conti kit, not some cheap knock-off.
The valve timing is actually still correct, but I'm going to tighten the belt again just to be sure.

Regards,
Reuselkopp.

Was the engine completely cold during the change?

Hello,
The car had been standing overnight, so it was cold. However, the check yesterday was performed with a warm engine. Could that be the reason?

Regards,
Reuselkopp.

Check it when it's cold.

Hello,
The tension of the belt, or the reading on the pulley, is naturally temperature-dependent. The engine expands more when heated than the belt does. Part of the load on the timing belt is compensated for by the (semi-)automatic tensioner pulley, and the spring inside it is subjected to greater stress as the engine temperature increases. This is noticeable as a slight shift in the indicator mark.
I have also observed this effect myself. Since Audi doesn't provide information about the engine temperature during the adjustment process for my model (B4 1Z), I assume a manufacturing hall temperature of 20°C to 25°C and set the adjustment accordingly.
Minor corrections after a period of use are also normal.
hg
Herbert.