Unable to remove temperature sensor from nozzle

[pollysaid 0]

Hi. I’m trying to remove the temperature sensor to install an Ollson Block on my Ultimaker 2 and it won’t come out of the nozzle. Any tips? If needed I still have the spare that came with the printer. 
Thanks!

[gr5 2,005]

Don't give up!  I've done several and I got tips from someone who has done about 100 of these.

 

I like to heat it up.  Before that I also spray WD40 in there.  If you do heat it up DO NOT let the heater come out while hot.  If it comes out it will very rapidly heat up to 600C and turn bright orange (red hot to white hot).  Because the temp sensor keeps saying it's not heating up.  Anyway I like to heat to 200C.  But this is not the most important trick.

 

The most important trick is to find a steel needle - a sewing needle or sewing pin.  Stick that down into the tiny crack between the block and the temp sensor and then push the needle over prying the sensor up (you will destroy the sewing needle by the way).  Repeat this over and over.  Remember that brass is much softer than steel and you may be denting it around the rim/edge but this is not a problem.  Keep doing this over and over and within a minute or two you may notice that the sensor is a few mm out of the hole.  At that point you can use needle nose pliers but be very careful not to grab the sensor by the wires.  Try rotating the sensor within it's tunnel first before pulling.

[pollysaid 0]

So heat it up and then turn off the printer?

[pollysaid 0]

Well, I accidentally started the heat up process with the cartridge removed. It got to mid 70’s turned orange, and once I noticed this I shut off the printer immediately. Here’s a photo. 

[gr5 2,005]

You did exactly what I said not to do.

 

The printer only has the temp sensor.  If the heater gets hot and it isn't close to or connected in some way to the temp sensor (e.g. through the block) then the printer thinks the block is cooling.  Because it is.  so it cranks up the heat.  I warned you it would get over 600C (it starts to glow around 600C).

 

Hopefully you didn't ruin the heater.

 

Look heating it is not the most important step.  But I usually work on it while it is hot.  With power on. Maybe I'm just a sucker for finger burns.  But it should work fine without heating. 

 

The key technique is using that steel sewing needle.  And prying forcefully steel needle slipping between the steel heater shell and the brass block.

 

 

[pollysaid 0]

OH. Okay, now I understand. How do I know if I’ve ruined it?
 

I appreciate your help, thank you. Had this printer for five years and this is first time I’ve had to do something in this realm. 

[gr5 2,005]

It's probably fine but once it's back together heat it to 220C and if it goes up to 220C without getting "heater error" then it's fine.  If it's broken the most likely failure mode is it won't heat up above room temp.  No heat at all.