I have a MK8 extruder, that has a fan mounted on it, if i extrude with the fan off, the filament gets warm and soft and collapses next to the gear and wont go into the little teflon tube. however if i turn the fan on, the extruder temp drops to 170C regardless of the settings in the slic3r (first layer 210C, other layers 205C)

has anyone ever dealt with this?

The fan isn't supposed to blow on the heater block. Maybe you have mounted it incorrectly.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Correct, fan should blow on cooling fins of the hot end, not the heater block.

Images of a MK8 show a fan on heat sink, are the fins up and down or left and right, Should be left and right.

Thanks, in my case its vertical. the problem is that it only has screw holes to be mounted this way. but yeah I believe the amount of airflow bouncing form the heatsink is enough to bring it down to 170C. I'll try fixing it