Temperature gauge reading has been steadily increasing over a period of time. Particularly when the engine is under high load.
Temperature gauge reading has been steadily increasing over a period of time. Even under normal load.
Temperature gauge reading drops slightly, then suddenly hits the red mark.
Temperature gauge reading suddenly hits the red mark.
Dave Bright, 25 Sep 2003.
This would indicate that the cooling system is loosing the ability to effectively dissipate the heat generated by the engine.
This may be due to old coolant, or a system that is silting up.
The solution is to renew the coolant with a drain, flush, and de-scale.
If this problem is not resolved, it will get progressively worse, even under normal engine loads.
This would indicate that problem above is getting worse and the cooling system is now almost incapable of dissipating any heat generated by the engine.
The solution is as above. Renew the coolant with a drain, flush, and de-scale.
If this problem is not resolved, it will cause expensive damage to the engine.
This is an indication that there has been a loss of pressure within the cooling system.
With the correct mix of antifreeze in a pressurised system, the boiling point of the coolant will be somewhere around 120°C.
The temperature sensor is designed to sense the temperature of water, not steam. Although steam is much hotter than water, as a gas, it has less heat transfer properties. If steam, or a superheated airlock has found its way to the top of the engine, as it passes the temperature sensor, the heat does not register, hence the drop on the gauge. As the steam, or airlock, passes out of the system, the reduction in pressure reduces the potential boiling point of the coolant. If the potential boiling point of the coolant is less than the actual temperature of the coolant, then it will boil instantly, causing the temperature to leap off the scale.
If some coolant has escaped the system, then again the pressure will drop, if this reduces the boiling point of the coolant to less than the actual temperature of the coolant, then it will boil instantly, causing the temperature to leap off the scale.