This is a easy enough sensor to change on a NB which picks up the water temp and tells the ECU which then uses it for a few other items on your roadster, one being for the cooling fan to kick in and off to stop overheating, it can become intermittent or just fail, stopping the fan from working...

The hinge bolt on the MK1 NA 1.8 alternator and on all models and versions of NB/NBFL Mk2/2.5 there after is a pain at service time...basically the bolt is fed from the back to the front and the outside leg of the alternator is threaded, which is open to the elements, the alloy of the alternator...