Power density (power/engine cubic capacity) of the latest passenger car Diesel and Gasoline engine keeps increasing with a focus to deliver best in class performance along with meeting CAFE and emission norms. This increase in power density increases the thermal load onto the coolant system. Coolant temperature sensor monitoring the coolant temperature, proper radiator sizing, optimum water pump flow capacity and thermostat tuned to the required coolant temperature range are the typical measures taken to ensure safe operation of the engine and avoid any over-heating.
Typical cooling system failures are mostly due to low coolant level, a defective thermostat, non-operative water pump & fan and blockage in the coolant circuit, etc. Most of these failures can be detected with the help of a coolant temperature sensor and pre-emptive measures can be taken to avoid engine loss. However, in the event of complete loss of coolant in the engine, the coolant temperature sensor will become ineffective since there is no coolant in contact with the sensor probe.
This paper presents an experiment that was conducted to see the effect of operating the IC engine without coolant. It is to be noted that the probability of a customer running a vehicle without having coolant at all is very less since he will be able to see overheating alarm in the cluster as soon as the coolant starts leaking. This experiment is conducted to assess the robustness of a system if it is run without coolant. There are several failures expected due to the running of an engine without coolant such as cylinder head gasket failure causing leakage of oil and gas, piston seizure, bearing seizure etc. It was noticed during the test that the coolant temperature sensor fails to detect the engine running in overheated condition and an eventual head gasket failure. The interesting part of this experiment is the consequential effects of this head gasket failure. Root cause analysis was performed to find the nature of the engine failure. Control measure to prevent catastrophic failure was designed and verified experimentally. Finally, a failsafe feature was suggested to prevent engine loss due to such failure.