Hello Vasanth

As you have mentioned , you have completed diploma in civil engineering and wish to do b tech in mechanical engineering.

Yes you will be eligible for pursuing any kind of engineering course after diploma . You will get direct admission to the second year of engineering so you will have advantage to save your one year.

You haven't mentioned , are you working  now? If you have a job or first you want to get a job then you want to pursue b tech in mechanical engineering  as part time .

If you work along with your further studies , it will make you financially independent too.

You can go for it.

To get more information you may refer the following link.

https://www.careers360.com/courses/mechanical-engineering-course