Toyota 3L Timing Belt.

Timing belts must not be creased since this will cause
the glass-fiber tension members to break inside the
belt. The belt's load-carrying capacity is then no
longer assured and it can tear.

Consequence: Engine failure.

Replacement interval:

Belt drive components are subject to aging and wear.
They therefore have to be regularly checked and
replaced. The checking and replacement intervals
are always specified by the vehicle manufacturer and
must be complied with.