Thermo switch

[chands99]

I have a lancer Station wagon C11V model which was manufactured in 1990. After using 14 years without trouble. The cooling system starts giving trlubles. Then I replaced Trermostat switch in the radiator, and then the problem was OK. But now thermo meter in the dash board gives very high reading though the engine is cooling properly, and radiator fan works properly. Is it a problem of thermometer or Temperature sending unit.

[New Forester]

When you say you replaced the "switch" in the rad, do you mean a thermostatic valve (round brass thing)? Or an electric switch or sensor of some kind? Usually the circulating water temperature is controlled by a thermostatic valve, but the electric fan is controlled separately by a temperature sensor switch. Don't know how your particular car works though. After replacing the bit in the rad, did the temperature gauge read incorrectly straight away? If so, I wonder if the bit you replaced was faulty, or more likely the wrong one? For example, thermostatic valves come in different temperatures (usually written on them). If the temperature gauge is moving up and down steadily as the engine warms and cools, I'd be surprised if it is also reading consistently wrong. You can test the valve by taking it out and heating it in a pan of water, using a sugar thermometer to measure where it opens.