I have an 87 944 and my temp gauge goes all the way up when I start the car and stays there but when i tap on the glass it comes down. Whats the problem and can it be fixed ?

 

on the glass or the gas?

 

I have a similar issue. Assuming that you don't actually have a problem with your cooling system (unlikely if your gauge is jumping into the red when the car is stone cold), this is likely caused by bad grounds in the dashboard. Do a search on "dash grounds" and you will see many suggestions for dealing with this. If you have problems with other gauges too (e.g., gas tank reads 3/4 when it's full), this is a likely culprit.