possibly an exhaust gasket blown or a hole somewhere near the zaust manifold?

By short engine I meant bottom end. There's no obvious vibration, and no noise when idling, just mainly between 1500 and 200o revs it makes what i can only describe as a hollow gurgley sound!

Short engine eh?

is there any vibration with the noise, does it do it when warm.
why dont you stick your head under the bonnet and see where its comming from?
mite be a timing gear problem, cracked roller or something?

70k. Had the short engine replaced though last year. It might just be a 'car getting old' sound?

could be the bottom end rattling. How many miles has the car done?

1999 Corsa 1.6i Sport.

My engine has very gradually started to make an odd sound. This only happens at low revs. Its not particularly loud, just a slight 'diesel engine' type sound at low revs between 1000 and 2500 revs. If I accelerate hard it sounds just fine.
I don't know how better to describe it really. I'm keeping her topped up with oil so don't think its that (and I don't get any kind of tappety sound on start up). Also had it serviced last week, no comments were made, other than 'slight oil leak from bottom part of engine, nothing to worry about though'
If anyone has any ideas, I'd be grateful.