Is engine a write Off - distribution pump?

[rugbyfan]

Hi All,
new to the forum as had an X5 for 3 months only but already a disaster :
Going along at around 60mph and my engine starts to rattle (ignition sound) and lots of white smoke out the back, switched off and engine ran on for about 5-10 seconds before stopping - it is an auto so I couldn't stall it. Thought it was turbo but sump has filled with diesel - bmw techie reckons the distribution pump went, the only cause that diesel in sump would be. Anyone know whether engine will be a write off or heard of this before?
Thanks
regards
worried