It's a known issue with Zetecs that on (very) cold starts
the timing belt might slap against that black plastic cover.
It should quiet as the engine warms up.
As a temporary fix, you can put some thick washers under
the cover mounting bolts.
Otherwise, do as Kremi said: have a look at the belt (or if
it's the factory belt at 90k, replace it soon regardless
of condition).
It's no fun getting stranded in the winter with a cold dead
engine...
T.
