Black silicone surround melting on hexagon hotend?

[dustmann]

I've been printing PLA for about ten prints now, and in the last three I have noticed some darker splotches in the layers. I have noticed there is a bit of PLA that looks like it has been melted and pushed up around the black plastic towards the hot end cooling fins. This doesn't seem to bother anything, but I have noticed more and more black silicone "smell" and black/brown goo oozing down the hotend and blending in with the extruded PLA.

Does anyone have any ideas? I will pull apart the extruder this week to see if I can clean out the gunk, but would appreciate tips on how to prevent this from happening again. I have been printing between 200-225, with the best results being in the 200-205C range. Bed temps are 70C. My hotend cooling fan runs constantly when the printer is plugged in.

[Starlord]

You may have PLA leaking around either where the nozzle or threaded tube screws into the heater block. I had the same issue. I got some pipe tape sealed them both. It is nylon and can handle to heat doing PLA or ABS. Might even work if you print in nylon. Haven't tried that yet. I have not had any problems since.

[TopJimmyCooks]

Leakage. The jacket itself does fine on long 250 degree runs. Make sure to heat the hexagon up to printing temps and then tighten everything down firmly.

[lakester]

I have the .4mm hex (3mm filament) w/ the stock MF fan shroud (though not for long methinks).

The silicon bootie has two little tabs on top, presumably to act as spacers between the bottom of the shroud and the top of the bootie.

My installation is such that only one of those tabs is in contact with the shroud..., and it's right there that the shroud is experiencing some melting and discoloration.

My printer is still low-time, but I have done a couple of 3-4 hour runs w/ ABS w/ HE temp at 250C.

The bootie itself seems fine.

[dustmann]

Thanks guys I will disassemble and try to re-tighten everything when up to temperature.