overheating problems

in the event that your car is erratically or inconsistently registering  in one point an overheat condition then suddenly it goes back to normal temperature then maybe the following are the causes:


1.  the thermostat of your car does not operate normally.  This thermostat is supposed to open at the point where the temperature of your coolant or water reached a certain temperature where this thermostat should open up. example , if this thermostat is designed to open at 50 degrees centigrade , and the coolant or water coming from the lower radiator hose reached the 50 degrees centigrade temperature , then supposed to be this thermostat should open up. there is a possibility that this thermostat is somewhat erratically malfunctioning.  that is why , there is a point when this thermostat remains closed despite the over 50 degrees water temperature triggering the reading of your temperature gauge in your dashboard deflects to the top. then all of a sudden , this gauge goes back to normal level, that means your thermostat open up. IF YOU ARE LIVING IN A COUNTRY WHERE  THE AVERAGE TEMPERATURE IS ABOUT  25 TO 30 DEGRESS CENTIGRADE, ( no winter time ) BETTER STILL REMOVE THIS THERMOSTAT, unless it has some serious side effect on engine performance.

2.  maybe the temperature sending switch is similarly malfunctioning erratically.  this switch is also suppose to react to the water temperature coming from the lower radiator hose . the same with that of the thermostat. when it sensed the needed water temperature passing thru it,  this switch will trigger a signal to the radiator fan to operate.  This is just like the thermostat , it may have reached the right temperature , but it did not reacted , that is why your radiator fan did not operate HENCE, the overheating...  But since your temperature gauge suddenly goes back to normal , it would seem that your temperature sending switch once again functions normally. WHAT TO DO. if you have replaced or have changed your thermostat OR you have removed the thermostat  and still the problem persist, TRY  removing the socket terminal of your temperature sending switch  ( located at end of the lower radiator hose or at the bottom of the radiator) put a jumper wire on the two terminal in it, run  or use the car , if the symptom did not persist then this sending switch is defective . take note that your fan will be operating continually until you shut off the engine. if the symptom does manifest still then maybe , the gauge, the sending unit, is the one defective.

3.  it may have been that your RADIATOR FAN  is similarly not functioning normally.  Even if  your temperature sending switch is perfectly good but your fan is not functioning normally then even if it is already its time to operate , it will not.  The possible reason is that , its shaft bushing is about to worn out.   

4. maybe the temperature sending unit is also erratically malfunctioning . this is sensor screwed at the cylinder head where the water temperature passes thru it and send a signal to the temperature gauge in your dashboard.  a single wire is normally attached to it that goes to the temperature gauge.