First, get a service manual. You need a chain wrench to hold the crank pulley
to loosen the crank pulley bolt. Buy a timing belt kit,Gates or AC Delco are good
The 2.2 is a clearance engine ,meaning if the belt fails the pistons won't hit the
valves. I use . autopartsgeek.com, bmaautoparts.com, Rockauto.com Etc.
I would replace the cam and crank seals ,water pump ,timing belt kit.
The tensioner should be ok for 300k. use torque wrench on everything(In Lb),
(Ft Lb). Don't touch the oil pump unless it is leaking. If you work on BMW this
is a piece of cake. JM