How much does an Asst. Professor - Mechanical Engineering make in Maine? The average Asst. Professor - Mechanical Engineering salary in Maine is $82,706 as of November 25, 2019, but the range typically falls between $69,310 and $98,151. Salary ranges can vary widely depending on the city and many other important factors, including education, certifications, additional skills, the number of years you have spent in your profession.