Coolant temperature gauge sender unit - removal and refitting
1 Should the coolant temperature gauge give incorrect readings (overheating or overcooling indicated, with no apparent accompanying symptoms), then the temperature gauge sender unit may be at fault, and should be renewed as follows.
2 Depressurise the cooling system by removing and refitting the radiator or expansion tank cap, taking precautions against scalding if the engine is still warm.
3 Disconnect the electrical lead, and unscrew the sender unit from the cylinder head.
Coolant temperature gauge sender unit location
A OHV engine B CVH engine
Be prepared for some loss of coolant - this should be negligible.
4 Smear the threads of the new sender unit with sealant, and screw into place. Refit the electrical lead, ensuring that a good metal-tometal contact is obtained.
5 Top-up the coolant level, and run the engine until normal operating temperature is reached (radiator fan cuts in and out). Check for correct gauge operation and also for leaks from the sender unit. No reading may indicate a poor connection at the sender unit - clean the terminals thoroughly.
6 When the engine has cooled down, top-up the coolant level again if necessary.