X reg Astra 1.6 SOHC thermostat replacement

With somewhat colder air temperatures, my 2000 Astra 1.6 petrol (X16SZR
engine type) is now showing all the signs of a thermostat failed in the open
position.
Has anyone managed to replace this without removing the timing belt and rear
timing belt cover? (as indicated by Haynes as being necessary)

As changing the timing belt isn't due for some time, I'm trying to balance
whether to get the belt done now (at 24,000 miles) along with the thermostat
replacement, or just leave it. Annual mileage is around 15,000.

Many thanks

 

Amazing how thermostats seem to fail - I haven't replaced one on any car
since the 70's, and I keep my cars for a long time - stats have always
worked reliably ..

Until my current car which has just had its stat replaced - it's < 3 years
old.

And guess what car it is? - An astra (previous cars have included 2
cavaliers)

Are they simply producing shoddy stats these days?