I have an Escort 1.8TD with 55k on the clock, had a cambelt done at 48k (previous owner). Last week the cambelt tensioner decided to spit it's bearing out without warning at idle (engine started clattering really badly). Had a new one fitted, but the clattering, particularly at higher revs, is still there and pretty horrendous. I thought it was perhaps the timing, maybe the belt had jumped, as the clattering sounds out-of-sync with the rest of the engine noise. Timing was checked, no problem, spot on, any ideas what else it could be? There's no real loss in performance (if you can call it that), not misfiring, no smoke, turbo kicks in a treat, but this has got me stumped. If a valve had hit the piston then it would either not run at all or run badly, which it's not, apart from the noise. It's just strange that it should happen after the tensioner went, making me think there's mechanical damage somewhere.
That does sound a bit odd, have you checked inside the timing belt cover for any debris or foreign objects left behind when the tensioner split? Sounds like it may be a bit of tensioner or somthing being kicked up by the timing belt and getting thrown around inside the timing belt cover.