Will trying to start a PhD late and after a gap of 4 years after my Masters, deteriorate my chances of getting admitted in a PhD program? I am 30 years old now and I graduated with a Masters Degree in Mechanical Engineering when I was 26. I have worked in the industry after I graduated, in 2 companies for one year each and then in 1 company for the remaining 2 years. In the last company I worked mainly in Machine Learning. Now, I am motivated to pursue research in this field.
Will my age and the fact that I have a gap in research after my Masters affect my chances of getting into a PhD program ?
At least in the United States, discriminating based off your age would be illegal, so hopefully that would not affect your chances. I started my PhD program at 25 without a masters after working for a year in an industry that was only tangentially related to my program.
I would also not expect the 4 year gap in education to make an impact. I've known multiple people who have done this after working for a number of years. If anything I would expect most programs to see it as a positive. Many people coming into a PhD program directly after an undergraduate degree would have little to no experience in the area, and as such would have a higher risk of deciding that the field is not for them and not completing the program. Somebody leaving a full time job to pursue research in the field is clearly making a deliberate decision to do so because of their interest in the work. See also responses to this very similar question
Will a 5 year gap between Undergrad and PhD hurt my chances?