Coolant thermostat failures

• thermostat valves open and close irregularly;
• depressurization of the system;
• incomplete valves opening;
• thermostat valves open at the wrong time;
• thermosensitive element is worn-out or broken;
• component operates with faults;
• compressor is worn-out or broken.

Signs of thermostat failures

• engine warms-up poorly or is overheated;
• fuel consumption exceeds the norms;
• engine power output is lower than usual;
• “Check Engine” indicator is activated.

Causes of thermostat failures

• strong vibration loads;
• unstable work of engine;
• loose fastenings;
• level of cooling fluid is lower than it is required;
• presence of motor oil in the Coolant thermostat ;
• cooling fan breakages;
• high pressure level in the system;
• strong clogging of the system.

Diagnostics

To check the thermostat proper functioning, performing of few simple actions is required. At first it is necessary to warm up the engine, then  measure the  temperature of the hose connecting the radiator to the Coolant thermostat . If the hose is cold, system works properly.

Coolant thermostat opening temperature shouldn't exceed 84–90°C. As well as the working temperature of the thermostat lower connection pipe. But we don’t recommend you to perform this operation without assistance of service station specialists.

Usually thermostat service life is 100 000 operational kilometers. However one should check  the existence of possible failures at least once a year. The thermostat operation analysis must be done when scheduled inspection of a car is carried out.

Replacement of thermostat

The damaged Coolant thermostat can't be repaired, it is to be replaced if faults were found. The operation is done by the standard tools. The installation of the part and measurement of opening temperature may only be difficult.  

Before replacement of the part it is necessary to drain a cooling fluid, to reduce a tension of clamps of heat exchanger inlet and outlet hoses. And only then the hose between the thermostat and outlet connection pipe can be disconnected. Coolant thermostat replacement is not very expensive. Therefore, it is desirable to change this part at the initial signs of breakage.