Issue with exporting sound,annoying clip that wont go away.

Everytime i cut out that fade in part from the sound and try to export it and reopen the edited sound in audacity it is still there, I want to make the sound a loop for a engine sound im using for a game.
Any idea how to solve this issue ?

Im using 2.1.0 for windows 8.

Thank you all in advance for your support and keep up the good work.

Don’t use MP3 format. This is a limitation of the MP3 format (and some other compressed formats).

WAV, AIFF, FLAC and OGG do not have this problem.