ya, I'm using the rcm heatsink, but I had it underneath with a fan blowing up, I'm doing this because If I put the fan on top, and I flip the truck, I would crush the fan. Maybe this is not good!

i think you would want the heatsink on top of the motor since heat rises. something has to be wrong for the motor to be 250*. what model are you running and what is your motor/esc, gearing, and batts? 250* is super bad for motor!

Here is my setup:

9xl with rcm heatsink
51/16 (strobe)
5S 8000 MaxAmps

I have the e-maxx but put on RPM arms, pro-line shocks (only 4), rpm axle carriers, mip axles, alum diff case, etc.

I did a roll test, I push it and it seems to roll fine. My spider gear did end up going, but woudl that cause enough friction?

Should I check my bearings? We do run in the sand and they do get gritty at times. I haven't changed them in months.

your setup seems fine to me. i would check the drivetrain for binding, like you mentioned. also, what controller are you using?

I'm using the MGM 16018-3, that is the one I have in it now. I also have the Querk 125B, which I plan to put in my rustler.

i don't really know how to get a definitive answer as to whether or not the motor is ok, as that could be the problem after 250*. i'm sure someone else will chime in to help out!

at this point, I have to throw out the motor, it doesn't work. I do have another in it now, that works fine. I put the heatsink on top, and have a masive fan, and will consider new bearings all around.

I have not opened up the motor, but when I spin the shaft, it will spin freely as if nothing is inside.

good, at least that weeds out the temp issue!