T-belt Tensioner only
 

Hi There,

Here is a situation I have found myself in that may have come up before..
Recenlty purchased an '04 1.8T with 84miles ~ 135km. Was under the impression the Tbelt service had been recently done at 75mi ~ 125km under previous owner's Audi extended warranty. However upon further looking into it - I discov'd this 'Audi warranty' only covers the belt service/replacement. And does NOT include tensioner and waterpump. Looks like for whatever reason this previous owner opted out of the added tensioner & waterpump service as there are no records of this at the shop. Leaving me with a fresh Tbelt job and a ticking time bomb for the rest of the system. Questions: How often do these elements fail? And what are the characteristics of the fail? Particularly with the tensioner? Does it always result in the same catastrophic valve damage as when the belt goes? Or are there any warning signs of a gradual deterioration? Assume I would immediately notice a water-pump failure on the temperature gauge, but could this also cause the engine to jump time? Is it worth getting the full job again merely 10,000km after the belt has been done? ?
Thx!