Front Left Motor Issue

[Bad Raven]

Simple Question:  Why would a front left motor (and ESC) run at much higher temps than the other three?

On one of my 150 Quads the front left motor started juddering sometimes, might run OK briefly, typical motor lost one winding symptoms.  I replaced it with matching make/spec along with matching make/spec ESC (though old ESC still worked).  It then worked OK but was still getting very hot. Too hot.

Motor is mechanically as free as the others.  Props match (diagonal prop swap and still the front left overheating)

The other three motors and ESCs are fine and run with just the chill off motors and ESCs after a minute hovering stationary.

Motor settings in Betaflight are normal, nothing different for this overheating motor than the others. Correct motor control (Oneshot125, old school!)

It's not the components as motor and ESC swapped around.  I even put a bigger motor on that corner (purely as a test!!), giving the motor less load with the same prop, and it STILL got very much hotter. Visual revs are the same, the sound is the same, the quad balances in hover perfectly, so FC working well.

Now completely stumped!!    

What next, swap the PDB????   

[ched]

That's weird. Only 2 things I can think of is high resistance in power wires/solder to esc at pdb end causing low voltage so motor/esc working harder?
Alternatively reflash FC, OK so it's clutching at straws but you seem to have tried everything else.

[Flyinegypt]

Just a thought but have you checked the static balance of the air frame? Could be heavier on that corner and having to work harder?

[Bad Raven]

To close this out, after trying several other things, resoldering ESCs (again, checking voltage at PDB outputs, reloading firmware, etc, I replaced the Flight Controller.

Today ran three back to back 850mAh 3S on it and equal temps on all arm mounted ESCs and all motors.

Go figure!