sihingwa wrote:@ Digitali
This was what happened, sorry if it is a long story;
1 I noticed coolant boiling out of its recovery reservoir. I took it to a mechanic and after several checks, blamed the water temp sending sensor. I replaced it @KES 5000
2. The new sensor 'worked' then 1 week later same problem.
I removed the sensor and tested its resistance using boiling water. I bought another sensor since the replacement one had constant resistance both when cold and when hot (in boiled water)
3 I tested the third sensor as above and it behaves (only when testing resistance)When put into the engine block, the car was still overheating...so I removed the wires so that the radiator fans are always on.
1. The boiling of the coolant out of its recovery reservoir was a correct indicator of overheating.
2.You tested the resistance what was the resistance at 100 degrees celcius?
3. The third sensor only only works out of the engine block- this is a clear indicator that there could be a short in the sensor circuit which could even be causing the sensor failure.
Another item to check is the fan relay which could be bad.
Again there are several ways to know if the coolant temperature sensor is malfunctioning, if the sensor is bad it will trigger a trouble code and the check engine light in the dashboard will come on, you can retrieve the engine code and see if it is related to the coolant temperature sensor, even if the engine control computer doesn't store a trouble code, there is another way to suspect a bad coolant temperature sensor : If your vehicle starts using more fuel than usual, starts having trouble starting when the engine reaches normal operating temperature or you notice black smoke coming out from the exhaust tail pipe, it is very likely that these symptoms are related to a bad coolant temperature sensor.