In mechanical stream, finding the jobs using online sites is too difficult. In private sector, core industries are recruiting through references only. But few companies recruit through consultancies. So maximum with online sites you can apply for government core industries like IOCL,BPCL,ISRO,MECL,SSC-JE,ESE etc.If you want try in online sites,then open the accounts in different job searching sites like firstnaukri.com , naukri.com , linkedin etc and upload your details,then search everyday for core industry jobs.