Noisy high mileage engine - possible areas to check?
I have a 1999 1.9TDi AHF with high mileage (205k) which has recently had a fair bit of work, including an exchange gearbox, new clutch & flywheel, as well as some work to re-engineer the head after a glowplug thread stripped and sheared in the head. I also had the alternator pulley replaced which reduced a lot of rattling in the engine. So i'm reluctant to bin the car after spending so much on it.
Since that was done about 6 weeks ago, the engine is starting to sound really rough internally, especially when cold and has an audible knocking noise which is evident when cold until the engine starts to warm up.
Clearly the engine may need some work, top end rebuild maybe? Would appreciate some advice on what work might be required to overhaul an engine with this kind of mileage. It does appear to drink a bit more fuel than usual now too, so i'm thinking maybe pistons/bearings/oil seals etc? Or am I barking up the wrong tree?
I wouldn't be doing this myself, so a guide on what I might expect to pay would also really help.