Ok, i have the boss DD-3 Delay pedal and i think there is something wrong with it. If there is only the guitar going into it and then into the amp (so delay before distortion) it sounds great, but that way it doesn't work with the distortion because the delays give less input and then aren't the same.

But, when i have it after distortion, like in the loop of after a pedal, it doesnt sound right at all. it does give repeats but the repeats sound really horrible, they sound like a huge digital mess.

Does anyone know what the problem is or should i take it back for another one?

I will record it later to show exactly what i mean.
Normally delay goes into your amp's effects loops. Have you tried adjusting levels and volumes of your pedal? I have only demo'd a DD-3 once and it seemed like your decent basic digital delay - so you should be able to get it to sound good. Perhaps try minimal feedback and levels ... almost like slapback delay and see if that works.

What kind of amp are you using? Oh, and if your pedal is new and you can't get it to work correctly take it back!
^Yeah, i played with all the settings but there is just something wrong with it. It works with a clean guitr going into it but not distorted, so somethings off.

I'm taking it back tomorrow and hopefully get a new one or a refund.