Bill,
Once you have the correct size belt, you ought to be able to take the
pulley off (two halves) and there ought to be a set of shims between the
two halves.  Take shims out to make the belt tighter and add some
between the two halves to make it looser.  It will likely take a time or
two to get the right tension but just tighten the three bolts while
holding the pulley halves together with the belt on.  Turn the pulley as
you tighten to avoid pinching the belt.  I'd stow the extra shims on the
outside of the pulley under the three bolts or leave them off and stow
them where you'll have them for the next belt change.

Hope this is helpful.
-Dana-

> Bill Johnson wrote:
>
> I am unsure if the water pump to crank V belt is adjustable on the 1.6
> diesel.  Page 19.4 of Bentley's shows shims on the water pump pulley.
> I am don't know how this works to loosen or tighten a belt.  Can
> anyone help?
>
> Bill