05 D4D Verso Noisy

[05YarisVersoLover]

My D4D Yaris Verso 53000 miles, runs and pulls very well, no lights on etc, regularly serviced etc but is very noisy - like the old flywheel type engines. Seems to be when idling and engine warm eg at the lights etc.

Had a D4D Yaris 05 from new (until an idiot slammed into it and wrote it off - wonderful car, loved it so have replaced it with same but Verso model) so not new to diesel sound - this sounds very different!

My garage says it may be the water pump ?could that be, no expert at all but can't see the connection myself, would really appreciate any advice - not sure whether to let them go ahead or not. Would it be better to take it to Toyota or will that just cost a bomb and be no further forward? Not sure what to do for the best.

Thanks in advance