Ive just changed my thermostat and rad fan temp switch as they been on car for ages.
The gauge used to always read high but would always drop to zero after engine switched off, but now it doesn't drop down all the way, it sticks at 1/4 of the way up, any ideas what causes this?

 

The temperature gauge gets its reading from the sensor in the cylinder head. So I don't see a relation to the parts you've changed.

When you say after the engine switched off, do you mean after turning the key to completely off? Because the gauge should only get 12V when the key is at position II. When it doesn't get 12V the gauge should drop down completely.

 

Hi Marc
Yes, when the car is turned off it still sits at 1/4 way up,
I disconnect the battery when not in use so it has now settled at the bottom

 

Sounds like the gauge may be faulty, have you tried gently tapping the cluster to see if it drops?

The rad switch has no bearing on the temperature gauge at all, so this is an independent issue.

Martin