How to Fix a Clogged GreatStuff Pro14 Foam Dispensing Gun

Post image for How to Fix a Clogged GreatStuff Pro14 Foam Dispensing Gun

by Tim Fulton on September 2, 2013

A little while back I was using my Great Stuff Pro14 foam dispensing gun to do a bit of exterior sealing on the house. While using it I noticed that it slowly started to clog up to the point where the foam was barely coming out of the gun. I didn’t think too much of it since I was getting close to an empty can. However, it just wouldn’t quite stop coming out while the trigger was pulled. This led me to think that the gun was getting clogged internally. I quickly decided to tear the gun apart to see if I could get it cleaned out before it was completely clogged up.

Before we get started, I’ll mention I took all these pictures upon reassembly of the foam gun. I’ll be covering both disassembly and reassembly in the same pictures since there are a lot of pictures. Also, it helps to have a tub of acetone to put parts into during disassembly to stop any uncured foam from curing inside the gun. So, lets get started.

foam gun

First, remove the foam can from the gun if necessary. Next, remove the screw from the adjustment knob on the back of the gun.

foam gun

Under the adjustment knob is a plate that is held in with two screws. Remove the screws and the plate.

foam gun

Unscrew the brass adjustment screw. There will be a steel ball and spring (which is under pressure) behind it.

foam gun

Behind the spring is another brass part. Notice that it fits into a slot on the trigger for reassembly.

foam gun

Remove the brass part and the rod. The rod may be stuck in there pretty good. A pliers on the shaft may help to free it, but be careful not to mar the surface of the rod. It must seal against o-rings in front of the trigger when you reassemble things.

With the rod removed, clean it up as well as you can. Make sure not to mar it up and pay special attention to the tip that seals the gun.

foam gun

Next, remove the foam can mounting piece. It has a hex base so you can use a wrench to remove it.

foam gun

foam gun

On the bottom of the mounting piece, there is a brass piece with a slot in it. Use a flat bladed screw driver to remove this piece. Behind it is a spring and a white plastic ball. You might need to remove foam to get to it. I just used a small flat bladed screw driver to scrape it out. Some acetone may help too. Try not to poke too far into the gun. The white piece is a plastic ball that seals things. If it gets scratched up it may not seal.

After things are disassembled, clean the foam off of everything you can. Just be careful not to mar up the sealing surfaces where the plastic ball seats.

foam gun

Next, remove the tip from the gun. It has a hex section to get a wrench on it to unscrew it. Once it is removed, scrape the foam out of the inside of it. The rod’s tip seals around the hole in the end, so try not to mar that surface.

When you go to reassemble things, I used some teflon tape to help seal things up. I used three wraps and I think a few more would have been a bit better, but mine did not leak.

foam gun

The tube is the next piece to remove. Again it has a hex section for a wrench. However, I couldn’t remove it with just that. I had to use a channel locks or vise grip type tool to get a good grip on it.

foam gun

Once it is removed, scrape the foam out of the inside of the tube. You probably aren’t going to be able to clean it perfectly. This is what mine looked like when I reassembled it.

foam gun

Now, remove the trigger. It has an e-clip on one side. Remove that and the pin slides right out and the trigger can be removed.

foam gun

Remove the brass piece in front of the trigger. It has two o-rings in front of it, so make sure to remove those as well. If they are damaged at all be sure to replace them.

When reassembling this piece, first just screw it in a little bit. Once the rod is reinstalled, you can tighten it down so it seals properly.

foam gun

Next up is to clean the handle section of the gun. Its a bit more tricky, but you can work at it from both ends. Clean it out as best you can.

Once everything is cleaned up to your satisfaction, you can reassemble the gun in the reverse sequence.

After this fix, my gun has been working very well ever since. Good luck with your own.


1 Darrel Koozer January 9, 2014 at 6:30 pm

I would like to purchase some parts for my pro 14 gun,do you sell them?

2 Tim Fulton January 10, 2014 at 8:40 am

Sorry Darrel, we do not sell parts for the pro 14.

3 Foamed up 333 February 18, 2016 at 6:04 pm

Has anyone been able to find parts for this gun??

4 oman February 8, 2014 at 10:56 pm

Great walk through and nice images.

I actually tried to apply this to my Great Stuff Pro Series 13 and found the construction quite a lot different. The only think i was able to do was take the barrel off by using a 9 mm wrench on the brass tip. This un-threaded the rod from the plastic body.

I was then able to inspect the rod’s insides as being very clean. It looks like the reason my gun had low pressure was due to the build up of solid foam around the gun’s tip. I scrapped this off with a razor being careful not to scratch the face of the tip. I believe this will do the job. I then used 3 revolutions of teflon tape on the rod’s thread before re-threading it. This may have been too much as the tape bunched up.

Looks like i should be using those plastic tips which came with the gun to go on the gun’s tip to stop this build up being a problem.


5 John Steever October 21, 2014 at 9:51 am

Thank you SIR!

I’ve been doing custom construction & remodeling over 45 years and love the control of this tool. I have had the problem with the gun clogging TWICE now.
I blamed me the first time and the gun this time – but- I just noticed the “screw the control knob shut when not being used”. My BAD!

Your information here is going to be a Life Saver! I didn’t know what to expect when I start taking it apart and now I’m not worried. 🙂

6 Mark February 5, 2015 at 11:18 pm

Thanks very much for this excellent breakdown of the very popular pro14 gun. If only there was a chemical that could dissolve cured poly, our troubles would be over. What a great gun this is despite the inevitable clogging, one must always leave the cartridge on the gun at all times and never let air into the gun to cure the foam, this is the best prevention.

7 ant March 21, 2016 at 1:37 am

Thanks! I had to use a punch to remove the white plastic ball in the top canister interface even after cleaning out the dried crystal looking foam. It worked! They should sell replacement parts.

8 Matthew August 24, 2016 at 2:03 am

U can buy cans of cleaning solution that screw on like foam.
If u spray a bit through the gun after every application it works wonders

9 Susan Greig September 1, 2016 at 8:00 am

THANK YOU for the step-by-step guidance and pictures! I thought I was going to have to shell out more money to buy a new gun since mine got clogged. Your post reminded me to shut the control knob and keep a can attached (didn’t do either) BUT you’ve also shown me how to recover from my mistakes. I feel confident I will be able to follow your instructions and fix the gun. I really appreciate the post.

Comments on this entry are closed.