92 325ic overheating
 

Hello everyone, I am new to the forum from Dallas Texas.
I recently purchased a 92 325i convertible. Car runs strong but noticed the car's temperature keeps bouncing around to Hot and back and forth. I replaced the thermostat hoping it would fix the problem.
Any suggestions? Any help would be greatly appreciated.
Thanks,

When it bounces, is it the difference between moving and sitting stationary (slow sweep?) or is bouncing erratically (quick sweeps?). In the first case I'd look at the electric fan, relay, and sensor. In the second case I'd suspect the SI board is crapping out in the instrument cluster.

^^ or the nut on the back of the cluster is loose and creating a bad ground. Tighten it and see if that fixes the issue.

or maybe the water pump does not work right?

Big Evil is on the money.
Miggy have you followed up???
Good luck.
I have a problem also that my temp gauge rises when the engine is stopped, after driving over 30 mts. or so. Mine is a 1987 325e Cabriolet.