Claiming on insurance for engine damage?

[sixspeed]

Quick question...

Is it possible to put a claim in on your car insurance for damage caused to an engine by a freak accident (sheared bolt which damaged the cambelt and caused engine/valve/camshaft damage)?

My thoughts are no, because you weren't involved in a road traffic accident as such. But then I saw a thread on here elsewhere about filling a diesel with petrol, and one poster said insurance companies will cover to replace the fuel system if required in this case... which got me thinking.

Any ideas?