'03 Passat Diesel sounds like a tractor

guy, not main dealer, changed the idler, was loose it seems, making a banging sound.

But ...still sounds like a tractor. Must bring it back but any idea's? It seems to sound a good bit worse than it used to - I've had it since nearly new. Maybe its just what happens to older VW diesels - I recall a Vento my dad had, was tractor-esque from day 1.

Serviced recently? What oil was used? Whats the miles? Could be an engine mounting become loose?

Could be anything Just turn the radio up a bit more

Changed the oil the other day (got the filter cover off, been about 2 years trying to do it, on the 3rd tool before it worked) and in the process discovered something about the tractor sound:

It doesnt sound too bad when started initially, but after about 2 minutes the engine level seems to drop and the tractor sound kicks in. So I think theres some form of automatic choke going on, and when that stops the engine is running at too low a rev and/or the level it runs at is causing resonance among a few parts of the engine.

I'll ask my mechanic about it at some stage, but does the above sound feasible?

Are you sure it was just the idler and not the tensioner was changed? I'd be inclined to have it looked at again. The 1.9 PD engine is not the quitest diesel in the world, but it was an inprovement on the one used in the Vento.