Add to ORKGA cooling curve test was done to demonstrate the effect of using different types of coolant in an I.C. Engine. The types of coolant used are: 1.Water 2.Ethylene glycol based coolants 3.Glycerol based coolants. Coolant concentration of 50% in both ethylene glycol and glycerol were examined. The experiment was conducted in a vertical Ruston diesel engine. The main parameters of the experiment were brake thermal efficiency and specific fuel consumption. Coolant outlet temperature was varied, while the engine speed was kept constant. The flow rate required to achieve a particular temperature for ethylene glycol based coolants and glycerol based coolants have been determined and compared with the flow rate of water