Help!!....engine Problem!! Knocking!!

[Jigs]

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Guys, Iam seriously confused..and helpless here. Really need this issue sorting out!...

I was driving along..and I hear a tapetty noise from the engine, It seemed rather strange, the noise, not a normal diesel thing you see.. I was told to stop driving, dont want the engine seizing up, just in case, and so I am without my baby!..not too keen on expensive repairs either!..Ok, Iam gonna bullet point the symptons..
- Loud tapetty noise, both at idle, and revving (tapetty noise increasing with revving), regardless of being in gear..seems to be coming from back part, near the oil cap.. I dont think there is a loss in power, but I didnt really wanna push it too much!..
- No engine management light, nor a oil light, thinking the oil is not getting up there, (perhaps a oil pump issue)..by the way I have checked oil level!.. I am still told by a few that it could be the oil pump, but I do not wanna go into changing oil pump, its like doing the whole timing belt again, isnt it??!.. well, my water pumps hasnt been changed!..lol..
- Turbo and power is still there..Idles normally too..

Its a 2000 Tdi PD 115..only 82K on clock..and cambelt done at bout 60K, like it deserves!..

Your thoughts will be much appreciated on this, thanks...