Coolant loss through the water pump bearing seal is commonly caused by a faulty cooling system pressure cap. With certain designs of the plastic pressure cap, if the cooling system overheats distortion of the pressure relief valve in the cap can cause the valve to stick and result in excessive pressure in the cooling system. It is recommended that the coolant pressure cap is always checked for correct operation, prior to the fitment of a new water pump. Thermostat Testing In order to confirm if the thermostat is operating as required, the correct testing procedure should be adopted.
Equipment required : 1) A container of undiluted anti-freeze mixture, to allow the temperature of the liquid to be raised above boiling point. (DO NOT use plain water). 2) A suitable heating element to raise the temperature of the liquid. 3) An accurately calibrated thermometer, with a range suitable for the thermostat to be tested. Testing Lower the thermostat into the container of anti-freeze, along with the thermometer, and heat the liquid slowly to the temperature marked on the thermostat, e.g 88 degrees, whilst agitating the thermostat. Let the temperature remain stable for one minute, then check for initial opening of the thermostat valve, Note: The valve will only just crack open at this temperature. Increase the temperature of the liquid to at least 14 degrees above the initial opening temperature, e.g.102 degrees, again allow one minute, then check the valve is fully opened. Allow the liquid to cool to below the initial opening temperature, then check that the valve is fully closed. Opening and fully open temperatures should be within plus or minus 2 degrees of those stated A build up of sediment coating on the thermostat can adversely effect the performance of the thermostat. download
