Abstract： Abnormal high temperature trouble happened in one cylinder of the diesel engine MAK 12V32 on a certain subsea platform in the South China Sea during the commissioning phase. Through the troubleshooting analysis of the data of crude oil engine operation, it is found that the Cyl7 exhaust temperature is too high. Then analysis of the reasons for the high temperature trouble of the exhaust gas by the comparison of pressure curve of each cylinder by using the electronic explosion pressure gauge has found that the pressure in the cylinder Cyl7 rises too slowly and the ignition is delayed. Further inspection shows that ablation phenomenon does exist in the exhaust valve itself, which can explain why the pressure curve is abnormal. Based on the above analysis, suggestions are given to avoid the ablation of exhaust valve caused by using high sulfur fuel.