Yesterday I wanted to print another repair part for my screen door (

Yesterday I wanted to print another repair part for my screen door ( but suddenly my J-head hotend started to leak . Any idea what can cause such a leak ? A broken PTFE tube ?

Bad seal between the brass tube and the heater block. A little Teflon tape should fix it

If the nozzle is to close to the bed the pressure can become to high in the nozzle and leak…

Yep, pressure is probably the culprit here. Also could be caused by trying to print too fast for a too small nozzle/speed or simply a nozzle clog. You could also try wrapping some regular teflon tape around the parts where the hotend combines.

@Brook_Drumm , I could have sworn that J-heads were sealed via the pressure exerted on the top of the PTFE tubing on the inside of the J-head.

@Mathias_Dietz , pull the filament out of the hot end, pull the hot end off of the extruder, there’s a hollow nut at the top of the J-head. Tighten that about 1/16th of a turn. Clean the end after applying heat, and see if you continue to get leaks. PTFE over time tends to get loose, and it’s likely it’s just a little loose.

If the PTFE tube heats up enough and has enough room, it can lift up off the bezel inside the heater core and allow melted filament to ooze up. It will run down around the threads like this. I had a similar blowout on a cracked J-head (my fault).

Looks like pressure problem. Maybe your nozzle is clogged? Sometimes there are bearing balls, stones, or metal pieces in the fillament. They can clog up the nozzle.

Thanks for all the comments . I will try to repair it on the weekend.

MAthias did you find the problem?