Skip to Content

3D Printer Nozzle Leaking: 7 Causes and Fixes

A leaking nozzle can cause your print to come out looking deformed and unappealing, we will explain some causes and fixes.

Written by:
Last updated:

Professionals and hobbyists use 3D printers to make everything from models and prototypes to novelty items and toys. They work by layering molten or melted plastic onto a print bed, gradually building it until the complete model. This technology has improved dramatically in the last decade since it became mainstream around 2007, but it still has its issues, such as leaking nozzles.

3D printer nozzles may start leaking because they have been put together wrong or because the extrusion temperature is set too high. Additionally, a dirty nozzle may cause leaking along with wrong adjustments or broken equipment. Fix by cleaning and refitting the nozzle, or check the settings.

A leaking nozzle can cause your print to come out looking deformed and unappealing. So, the rest of this article will investigate some common causes and solutions to help you can get back to printing. Then, with some adjustments and tinkering, you can get your models to look as intended.  

1. The Nozzle Was Assembled Wrong

One of the most prevalent reasons for a leak is the incorrect assembly of your nozzle. Unfortunately, this problem is common among novice 3D printer hobbyists who may not be as familiar with the setup. 

If you put the machine together without reading any instructions or didn’t check everything if it came pre-built, chances are, the nozzle itself is the culprit behind leaks. 

This problem isn’t just for hobbyists; many 3D print enthusiasts face the same issues.

How To Fix

If you think the problem is with the nozzle itself, you’ll want to take it apart and reassemble it. Just remember to be gentle, as some internal parts are delicate and easy to break. 

Here’s how to remove and refit a 3D printer nozzle:

  1. Disassemble the nozzle by removing the tip and the heat break from the heat block.
  2. Check that everything is in working order, i.e., look for cracks or damage.
  3. Most heat breaks will have a gap along the tube, so place the short end into the heat block. 
  4. Don’t screw the heat break too far into the heat block.
  5. Place your nozzle into the other end of the heat block, leaving a small space between the two.
  6. Continue screwing the heat break into the heat block until it firmly touches the nozzle from the inside. 

Here’s a quick video that details this more clearly:

2. The Extrusion Temperature Is Too High

Another well-known reason your 3D printer may be leaking is due to high extrusion temperatures. 

Different materials heat at different temperatures. So, depending on what kind of filament you’re using, you may need to adjust your settings for the right amount of heat.

High heat can cause a leaky nozzle and stringy models. 

For example, this SUNLU Store PLA 3D Printer Filament from is affordable and comes in a variety of colors. Its recommended extrusion temperature is 215-220°F (419-428°F).

In contrast, this Gizmo Dorks Low Odor ABS 3D Printer Filament, also from, suggests an extrusion temperature range of 225-250°C (437-482°F). It’s just as affordable and also comes in a variety of colors. 

However, if you were to use the Gizmo Dorks brand at a higher heat and not lower the nozzle temperature when you changed to the SUNLU PLA 3D Printer Filament, you’d likely see leaking.

This problem may also occur after replacing a hot end, a cooling fan, or changing the mainboard. 

How To Fix

First, check the suggested nozzle extrusion temperature of your chosen filament and make sure everything matches up. Also, remember to change the temperature when you switch to new material.

Another option is to take a look at the heating graphs in the console of your choice, such as Octoprint or Simplify3D. If the charts are jagged or uneven, you may have a heating problem which would cause leaking and stringy prints. 

Try downloading free software which auto-tunes the heat, such as PID Autotune. It’s an add-on to your 3D printer software and is understandable once you get the hang of it. Try a few small test prints to see if it fixes the problem before attempting a larger model.

Lastly, if using auto-tune doesn’t fix your problem, it may be due to your newly replaced mainboard. In that case, you’ll likely need an additional capacitor.

For a more in-depth understanding of this, check out this video:

3. The Nozzle Is Not Retracting Filament

When using a 3D printer, a common leaking problem called stringing happens fairly regularly. This is when the nozzle extrudes plastic while moving from one print point to the next. No filament should be extruded during this move, and it looks like strings or webs over the print. 

Normally, the nozzle will retract a little bit of the melted plastic as it moves from one point to another to prevent dripping or stringing. If your 3D printer is not set up to retract, you’ll likely see leaking around the nozzle.

Luckily, if stringing is your problem, there are a few ways to fix it. 

You may think that stopping the extruder will help; however, this can sometimes make it worse. So, before continuing your print, you may want to look at your adjustments and settings for your retraction. 

How To Fix

Using no retraction during your print will probably cause stringing. So, using just a small amount of retraction should allow for a smoother and stringless pattern. 

During retraction, melted material doesn’t necessarily go back into the nozzle. Instead, it relieves pressure on your nozzle, so plastic doesn’t ooze while the nozzle readjusts. 

The splicing software should automatically set retraction, so check the file to see what it says. If the box is not selected, that’s likely the cause of the leak. 

Always double-check that retraction is set to ‘yes’ or ‘on.’

If retraction is on and you’re still experiencing leaking or stringing, check to see how much filament the nozzle is retracting. 

For example, if it’s set to retract 3 mm and leaks between moves, change the setting to 4 mm or 5 mm. In general, 5 mm is an excellent place to start. From there, change just 1 mm at a time until you get the results you need. 

Some filaments may even need 7 mm of retraction, so test your materials to be sure. 

Check out this video to hear more about retraction: 

4. The Nozzle Needs To Be Preheated

You may notice that your model has an unusual amount of leakage at the beginning of your print, but otherwise, it prints correctly after your model gets going. That can happen from excess extrusion clogged inside of the nozzle. 

That may not be a problem for newer models due to technology development and updates; however, with some older 3D printers, you may need to prime or preheat your machine. 

It’s common for nozzles to have a small amount of excess plastic. But if you notice that your print is getting leaky before your design even begins, chances are you need to prime the nozzle.

How To Fix

By preheating or priming your nozzle before you begin printing, you’ll reduce the amount of leakage. You may want to check your datasheet and model of the 3D printer before deciding on what temperature you should prime your printer to and for how long. 

Always check your guidelines before tinkering with temperatures and ensure that you aren’t overheating your nozzle or heat box. 

Alternatively, just print a wider bed or skirt around your design to use up any leftover filament. This gets snapped off when the print is finished and cooled. 

5. The Nozzle is Dirty 

Having a clean and regularly maintained 3D printer nozzle can ensure that your prints stay sharp and smooth. 

You’ll probably encounter many problems from a dirty nozzle, including leakage or clogging. In addition, you might see missing layers or the nozzle not picking up materials. 

It can cause too much material to leak out or not enough and may make your prints look inconsistent or rough. 

Of course, if your models are for PPE medical usage, having a smooth pattern is essential. But even hobbyists want their prints to look good.

If you don’t remove your nozzle and clean it, you may run into these problems and even damage your machine. 

How To Fix

A clogged 3D printer nozzle can lead to leaking. The good news is that there are a few ways to clean your nozzle, such as:

  • Remove the clog by manually pushing a piece of filament through your extruder. 
  • Clear the clog with a small needle. 
  • Try a cold pull with a new filament.

To perform a cold pull:

  1. Remove the Bowden tube from the extruder if you have one.
  2. Heat the nozzle either as hot as the machine will go or at least high enough to melt the two filaments (the one that’s clogged and the one you’re using to force it out).
  3. Use a strip of nylon or another filament and push one end into the heated nozzle.
  4. Push until you see filament leaking out, and then reduce the temperature to zero.
  5. Keep pushing until the material stops dripping.
  6. Leave the nozzle and filament to cool.
  7. Reheat the nozzle and remove the nylon or filament, which should have any leftover clogged material attached.
  8. Repeat as necessary.

Here’s a helpful video that explores these methods further: 

6. The Coaster Adjustment is Wrong 

3D printers are somewhat complicated. These machines are high-tech and create some exciting and valuable models. However, if you are using one of these printers, you may have some adjustments in your settings that are causing some leakage.

You should always check your user manual to ensure that your temperatures and retraction are adjusted to the proper settings before disassembling your machine. That can save time and effort if it’s just a quick setting fix. 

One of these settings is called the coaster adjustment. You can use it to correct errors such as stringing or leaking. It can also give the model a smoother surface. 

How To Fix

The first step is to understand the use of the function. Then, to avoid mistakes, you may want to use a test print to ensure your settings are correct. 

Set the coaster at 0.064 and make a few test prints to experiment with these settings before deciding what to put your volume on.

Remember that the minimum coasting level should remain at 0.08. The best part about 3D printing fixes is that you can decide what works best for you and your setup. 

7. The Equipment is Broken 

If you’ve tried every previous step and your nozzle is still leaking, you may need to replace your entire nozzle. That can happen when nozzles get overused or become clogged to the point of no return. 

You may have accidentally broken something inside your nozzle that is essential to a properly working 3D printer. It’s not uncommon for hot ends to become worn out. Like anything else, over usage can cause damage. 

How To Fix

If this is the case, then your best bet would be to pick up a spare nozzle. Make sure to research what size and shape hot end you need for your machine. 

Be sure to use the necessary precautions to prevent burns or other injuries while replacing your hot end. 

Check out this video to see how to change a 3D printer nozzle:


3D printers are an excellent way to create prints and models, and many companies are now even using them to make PPE for medical use. 

This technology is advancing at an astounding rate, and more people are becoming interested in 3D printing for anything from toy designs to board game models. 

However, with development comes problems and bugs—one of the most common being leaking filament.

Written by:
Last updated:

About Ben

I started 3D printing since 2013 and have learned a lot since then. Because of this I want to share my knowledge of what I have learned in the past years with the community. Currently I own 2 Bambulab X1 Carbon, Prusa SL1S and a Prusa MK3S+. Hope you learn something from my blog after my years of experience in 3D printing.