Thankyou all for your advice.

I think that as the garage has said that the chain has snapped, the garage must be fairly certain about this fact. I've spoken to a few mechanics and they have all done a sharp intake of air when I've mentioned it.

I was looking at old 540i and 740i cars with the 4.4i engine and thinking about buying the car and doing an engine transplant. These cars are only going for about $5000.

I hadn't thought about ebay for a used engine, let alone a rebuilt one. I think that price is fairly good considering...... I think that'll be the route to go.

I'll keep you updated.