APRIL 2019 91The M20 has a
belt-driven cam,
and the belt and
tensioner roller
should be replaced
every 30,000 miles.
Replace the water
pump as well,
because you’ll need
to take most of it
apart again to fit a
new pump when
it invariably starts
leaking a few weeks
after the belt change!
The 1990 518i – with
the M40 engine –
also has a belt but,
with an inexpensive
locking tool set, they
are really easy.
The V8s are good engines, but they all had Nikasil bore coating. For those that
don’t know, this was a nickel/silicon coating that was sprayed onto the bores at
the factory. Unfortunately, the aggressive, cold-start fuelling, coupled with too
many cold starts, would damage this bore coating, while the excess sulphur in UK
fuels would attack and lift it. Most were replaced years ago with the Alusil blocks –
a block made from alloy with silicon particles, rather than a coating.4
3