This is a 2.0 dti from a 52 plate vectra y20dth 160k, recently purchased but does have service history stamps with oil changes but was over due a change. Last service was 134k 14/02/08 with oil filter and fuel filter change.

http://www.youtube.com/watch?v=GasVIdMt3Pg
http://www.youtube.com/watch?v=JM5S5UTUqHc&NR=1

Basically the noise is very metallic sounding and only happens when revving the engine and under load, when idling the engine seems fine. I've replaced the oil filter and oil, there was about 5 litres removed. Also removed the alternator belt and the same noise was heard.

My mechanic friend thinks it may be the bottom end, but before i try and replace the whole engine i would appreciate either confirmation or any other suggestions as to what the problem could be and how i would go about fixing it.

If i do need a replacement engine how much am i looking at to buy one? and does it have to be a like for like replacement ie y20dth or would another engine also work?

Thank you, any help is much appreciated
Andy