I have a 90 crx si and the car never fully warms up , the heat dont really get that hot and the fan never comes on , i replaced the thermostat today with a 180 degree unit and refilled the system and bled it and still the same problem , i noticed though that the top radiator hose gets nice and hot but the lower part of the radiator remains cold and the lower hose is actually real cold to the touch , what does this mean ? I felt the heater core lines and they are hot just like the upper rad hose but the lower hose is just really cold , could sometyhing be clogged or the water pump be bad , any help would be awesome thanks

 

if the pump was bad or something was clogged up you would more than likely be overheating not staying too cool.

 

Honestly, I think your cooling system is fine.

 

The only time my 91 Si gave me any overheating trouble was after it blew off a heater hose, empying the entire cooling system. I had overcooling trouble on mine as well, it's probably a common problem. The 4th gen Civic/CRX Si has a full width radiator, which is more than adequate for a beater 1.6/1.5L sohc. Ever notice that the newer civic's have a 1/2 length, but same width radiator(excluding b16 equipped).

 

Did you buy a cheap parts store thermostat? I wouldn't trust those for anything. Put in an OEM Honda thermostat.

If your car is not overheating though, the only thing I can even think of would be a stuck open thermostat. If not, your car is probably fine. How cold is in in PA right now?