The blow-by tests were carried out on a 6-cylinder turbocharged and intercooled diesel engine under the operating conditions of different engine speeds, torques, oil temperatures and maximum combustion pressures. The test results showed that engine speed and torque were the main influencing factors and oil temperature and maximum combustion pressure had little influence on blow-by. The blow-by generally showed a linear increase trend with the increase of engine speed under the same torque condition. The blow-by increased approximately 12% with every 10% increase of speed. The blow-by also showed a linear increase trend with the increase of engine torque under the same speed condition. The blow-by increased approximately 5% with every 10% increase of torque. The condition of largest blow-by did not agree that of peak gas leakage rate. The relatively high leakage rate occurred at the intersection of medium speed and medium torque.
