Hi,
so I’ve replaced 2 of my motors and as i was testing them out, they are running very hot even after 30secs of running. Is this a case of me having to break them in and they will run as cold as the rest of my motors, or should I be worried about something? These are brand new out of the box.
You could try ,
Shorter motor bolts , or washers under the bolt heads .
My opinion would be that , no , they won’t run in and become cooler by themselves.
Am presuming that it’s just the two new motors getting hot - are they defo exactly the same motor ??
(Motors without props will run hot , but youlld think it would be even )
Lowering the d term can help with hot motors but can’t see that that’s relevant here.
I suppose also , if in a self level flight mode , on a propless bench test , then some motors might be running more / hotter on one aspect , but I’m grasping at straws here. Have you tried a short flight test ?
Depends what you mean by hot
On a bench, propless, a warmness to the touch is normal, but if they are uncomfortable to touch then you certainly have a problem
Check current drawn by the ESC on the hot running and cold ones if hot are drawing much more, check on previous posters suggestion to ensure fixing screws are not too long and touch the motor winding wires
Cheers
Steve 
Yeh shorter bolts and a drop of oil helps very much so.