My '89 is running cool by the temp gauge on dash. It never gets beyond 9 AM. Then the temp needle sometimes bounces below the cool mark. I replaced the thermostat and gasket with Honda. I got a 190 degree therm and the one removed was a 180. Didn't make any difference. Filled back up with Honda Coolant, ran with heater on and bled the bleeder valve. Drove it more and bled it again. Same issue. Needle never gets beyond 9 am and it keeps going back below cool mark.

I see two sensors immediately to the right of the bleeder valve. I wiggled those wires. No change.

What are my next options?

 

Honda's usually run about a third of the way up the needle.

 

Understood, but why does it keep slowly going to the cold mark and then back up to 0 o'clock position?

 

Coolant temp sending unit is more than likely going out. The resistance when cold should be 142 ohms and 49-32 ohms with the engine at operating temp (both fans on and t-stat open).

Those specs are for a 4g btw but I highly doubt that the sensor acts any differently in your model, it's just a simple thermosistor.

 

+1

 

you could always install a seperate aftermarket temp to see if the car is running properly