2.2jts blown after timing chain change
Not the happiest occasion for a first post, but the story goes like this:
Bought a Brera 2.2jts last year with 46000 km on the odometer and symptoms of timing chain stretch. Started losing significant power earlier this year and had a workshop replace it using the Alfa Workshop kit. The car was absolutely fabulous when I got it back - throttle response and power was amazing compared to what it had been. That lasted for 13 days and maybe 200 km.
While driving, a noise which resembled the familiar valve ticking on my old Fiero suddenly appeared. I limped back home as carefully as possible, the engine ticking interemittently, but still running ok, no engine light and no apparent power loss. Left the car parked for two months as I was away during summer and didn't have time to look into the problem, before I finally took it for a test drive. No ticking when I left the garage. After approximately 200 meters of driving it reappeared and turned into a noisy rattle in a matter of seconds. Pushed the clutch and the engine died immediately. Starter engine didn't even want to engage and had the car towed back to the workshop.
Told the workshop what happened, that I suspected the engine was blown and that it was related to the timing chain. After two weeks they tell me I'm right, one cylinder is torn to bits and the engine need to be replaced. They can't tell me how it has happened, but insist it has nothing to do with the timing chain replacement, which I have trouble accepting.
Hence, my question is: Is there any way to explain this scenario which doesn't include a) Misaligned timing chain or b) Poorly adjusted timing chain tensioner?