This research was aimed at investigating effectiveness of CLIL to improve students' English for Mechanical Engineering (EME) competence. EME is designed for mechanical engineering students who learn English as a supporting subject. Two groups of semester two Mechanical Engineering student who had same level of English ability (according to their English lecturer) were involved as research participants. They were divided into two groups, one experiment group and one control group. Both groups were given a six-session English learning each. The experiment group was given CLIL approach and the control group was given English learning with conventional method and materials. The topic of lesson was 'welding'. Evaluation of learning activity was performance test of presentation. Research data obtained were students' performance of presentation and perception. Result of analysis revealed that students were more competent in presenting their work. Their perception on CLIL was positive.