Cat E120B excavator. Today the water temp alarm sounded, the temp gauge went back and forth on the dial gauge, I opened the engine hood and left it open, fan was working, coolant was in the system and the reservoir bottle. After a while the alarm shut off. The temp gauge did not go into the red zone it moved up and down in the green zone. Wondering what is acting up. Water Temp gauge when bad? why would the alarm sound off, engine compartment was hot, oil level was good. Any comments?
Sounds like the temperature sensor is wonky.
Or maybe an air lock in the cooling system.? Depends how rapidly the sensor reacts to temperature changes i guess. The fact that the cooling reservoir bottle has coolant in it is not a 100% nailed on confirmation that the system itself is full. Post a machine Serial Number to help look up technical information.
Machine serial number 6JF00719 Cat E120B
You will need togo digging arouns the engine.There is both a high temperature switch (contacts open at 225F with rising temperature and close at 200F with falling temperature) and a "water temperature unit" which I assume should be a sender of some sort. The temperature switch is #4 in the illustration below. The "water temperature unit" is #9 in the illustration below. It appears to be in a connection right on top of the water temperature regulator (thermostat) housing. Try disconnecting the single wire that goes to it ans observe what the gauge does with the wire disconnected. Then touch the wire terminal to ground on the engine block ad again see what the gauge does. Come back with your findings.
Nice help there, Nige.
Have not needed to operate it yet, will get back to you when its worked.