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Quick Oil change method for pneumatic spearguns

popgun pete

Well-Known Member
Jul 30, 2008
3,443
778
153
Australia
The usual procedure for changing the oil in pneumatic spearguns is to let all the air out, unscrew the muzzle and then pull the piston out of the inner barrel. After that you can tip the gun upside down and pour the oil out of the inner barrel. Guns with a power regulator block tend to trap oil in the front tank, so to remove everything you can twist the nosecone off and then pour the oil out of the front tank at the same time as you empty out the inner barrel.

This alternative method uses the air pressure in the gun to blow all the oil out of the rear inlet valve and to do that without making a big mess you need a gadget like that shown in the diagram below. This device was developed for the "Taimen" which has a thick plastic valve stem, so you don't want to push that stem with anything sharp, instead use just a smooth ended rod that fits neatly in the inlet valve port. The gun is held with the muzzle pointed upwards and vertical and then pushed firmly onto the vertical rod which cracks open the rear inlet valve and the oil sitting in an accumulation in the rear of the gun is all blown out by the air pressure acting above it. In a big gush of air escaping all the oil is blown into a receptacle such as an old ice-cream container for your subsequent inspection to see if there is any water or foreign materials contaminating the oil that would necessitate gun dismantling to investigate the source of any problems.
gun cleaning oil removal R.jpg

If the oil looks good then you discard it, put fresh oil in a glass bottle or jar and suck it up with the hand pump and attach the gun to the pump, the gun still being held muzzle up and then invert the assembly and with a slow firm push press down on the pump handle and send the oil in the pump into the gun. Repeat as necessary to ensure the correct amount of oil is replaced in the gun and that is all there is to it. Make sure that the gun is set to full power when you do this as compressed air pressure can act on all the oil sitting in the rear end of the gun.

Note that a slow push is required as you don’t want the oil being forced in too rapidly which may blow the inlet valve “O” ring out of position, an unlikely outcome, but better to be safe than sorry.

Periodically the piston needs to come out to check for any wear and scratches on the piston and its seals, but this is unlikely unless you dive in very dirty and gritty water or spear in the shore break where schools of fish often run through feeding on material being churned up off the sandy bottom. I have bumped off quite large flathead doing this when I saw them zipping around my fins while standing on the bottom, so swam out and then turned back to open fire on the fish which are very hard to hit, so more ass than class in hitting one.
 
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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,443
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Australia
It occurs to me that the gadget shown in grey is something that could be 3D printed, or turned up out of wood with a metal rod for the probe that pushes on the valve stem or metal ball as the case may be.
 
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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,443
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Australia
This gadget is basically a stand with a rod than can be changed over for different speargun models, however most using ball inlet valves are exactly the same size, so in most cases the one rod would be universal. Guns like the "Taimen" using a valve stem are the few exceptions today, in fact ball inlet valves have been around for decades and go back to the early seventies. The "Taimen" is unusual as it has no valve spring, the valve stem being a sort of jiggle pin, the reason being that the compact design has no room for a biasing spring. The valve stem was originally metal, but is now plastic to prevent galvanic reaction with the alloy rear housing. This is because the tail cap always floods and water can reach the valve stem, the tail cap being a plastic bung which just pushes in and is held in place by an upper transverse screw in the rear of the clamshell plastic handle. Being plastic the valve stem is fatter than usual and needs a broader flat ended pin that will not bust the valve stem, hence pointy metal objects are forbidden if you need to let the air out of the "Taimen" gun.

This method will work for every pneumatic speargun that has a rear inlet valve, the only exception would be guns that don't have a hand pump connection and use the inner barrel as a hand pump, such as Zekinka guns. However even some Zelinksy system guns today have a rear inlet valve, such as the Pelengas "Z-linka" shown here.
Pelengas Z-linka 50 cm in case.jpg

Zelinsky system guns, often referred to as "Zelinkas", are uncommon in the West, but are highly sought after in Russia, Ukraine and the former Soviet Republics.
500 3.jpg

This one is constructed almost entirely from titanium with a stainless steel inner barrel and is a very long lived underwater weapon in terms of its service life. Note the interesting pointed white colored tip on the head, almost looks like some type of ceramic. Bring on the monsters and blow them away when using these high power guns!
 
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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,443
778
153
Australia
Note that upside down positioning of the gun is vital to using the air pressure as a driver to force all the oil sitting below it to be ejected, the oil comes out first followed by the compressed air. As with muzzle removal to do the same job it is best to stand the gun with muzzle up and butt down in a room corner for say 20 minutes to allow the oil to accumulate in the rear end of the gun with the power regulator set to full power.
 
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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,443
778
153
Australia
One thing that I forget to mention is that with power regulated pneumatic guns you need to set them to "full power" and have the gun slightly tilted so that the oil runs down through the now open transfer port before you press on the inlet valve. The tilting places the transfer port to act as a drain hole for the front tank by being the lowest point, otherwise oil sitting inside there will not be blown out. That gun positioning then allows all the oil in the gun to run down into the rear end of the inner barrel which you are intending the air pressure release to blow all the oil out of via the back end of the gun.
 
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floatingbeatle

Well-Known Member
Nov 12, 2013
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East Ballina
One thing that I forget to mention is that with power regulated pneumatic guns you need to set them to "full power" and have the gun slightly tilted so that the oil runs down through the now open transfer port before you press on the inlet valve. The tilting places the transfer port to act as a drain hole for the front tank by being the lowest point, otherwise oil sitting inside there will not be blown out. That gun positioning then allows all the oil in the gun to run down into the rear end of the inner barrel which you are intending the air pressure release to blow all the oil out of via the back end of the gun.
Very interesting method Pete. How much pressure is likely to be dispelled from the gun when performing this manoeuvre? I imagine it would not be too much, and for those of us without a manometer, do you think it would affect a guns aim?, or would that be negligent unless a lot of pressure was lost?
 
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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,443
778
153
Australia
Very interesting method Pete. How much pressure is likely to be dispelled from the gun when performing this manoeuvre? I imagine it would not be too much, and for those of us without a manometer, do you think it would affect a guns aim?, or would that be negligent unless a lot of pressure was lost?
The intention is to let all the air out as this is being carried out to change the oil in the gun. You add the oil to the hand pump and pump it in using a slow push of the pump handle, ideally after say a dozen pump strokes to put some air pressure in the gun first. Then you re-pressurize the gun as usual. If the oil removed looks contaminated then it would be best to open the gun up and check for a cause and any corrosion inside the gun.
 

Diving Gecko

shooter & shooter
Jun 24, 2008
1,430
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Shanghai
Very interesting method Pete. How much pressure is likely to be dispelled from the gun when performing this manoeuvre? I imagine it would not be too much, and for those of us without a manometer, do you think it would affect a guns aim?, or would that be negligent unless a lot of pressure was lost?
You can measure/approximate the pressure in your gun using a regular bathroom scale. This method should definitely suffice if you just need a before and after measurement - say, before and after servicing your gun. I've gone out once or twice with a gun, which I had over loaded and it pretty much ruined that day's spearing.

 
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floatingbeatle

Well-Known Member
Nov 12, 2013
39
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East Ballina
You can measure/approximate the pressure in your gun using a regular bathroom scale. This method should definitely suffice if you just need a before and after measurement - say, before and after servicing your gun. I've gone out once or twice with a gun, which I had over loaded and it pretty much ruined that day's spearing.

Yes. I have read the post by Tromic using the bathroom scales and it worked for me on my old scales, but I now have stupid digital scales and they’re hopeless. I’ll need to get myself some good old fashioned scales again. I just wondered if there was a great loss of pressure in changing the oil as per Petes’ method. Would be useful if you don’t need to pull the gun down completely.
 

Diving Gecko

shooter & shooter
Jun 24, 2008
1,430
347
138
Shanghai
Yes. I have read the post by Tromic using the bathroom scales and it worked for me on my old scales, but I now have stupid digital scales and they’re hopeless. I’ll need to get myself some good old fashioned scales again. I just wondered if there was a great loss of pressure in changing the oil as per Petes’ method. Would be useful if you don’t need to pull the gun down completely.
I'd say you can loose quite a bit of air very fast when playing with the valve. That actually happened to me very recently. I don't have my One Air gauge with me and needed to take out just a little air to make the gun easier to deal with. I have since put in more than 200 pump strokes and the gun is still easy to load so that little became quite a lot.
But if your intention is to just change the oil with minimal fuss, I think you may be on to something. I guess, if you have the gun sit upright long enough, so most of the oil is sitting on top of the valve, then when the valve is depressed, the majority the oil should come out right away. And if you can modulate it to go slow enough and stop right as your hear air swooshing out, you might only loose a few bar.
And then, as Pete says, if the oil looks clean enough, just load up a new dose in the pump and inject.
 
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ECK

Well-Known Member
Jan 4, 2014
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When I took apart my Airbalete, I found that there was no liquid lubricant. Everything was smeared with some sort of white substance. We defined it as a silicone grease with PTFE. It is not washed off by water and terribly slippery. And now I use only her. And there is no dirt to disassemble the gun.
 

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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,443
778
153
Australia
The early production "Airbalete" used grease, but in order to keep corrosion at bay inside the gun they switched back to using oil as unlike grease it continually moves around inside the gun.
 

floatingbeatle

Well-Known Member
Nov 12, 2013
39
6
48
60
East Ballina
When I took apart my Airbalete, I found that there was no liquid lubricant. Everything was smeared with some sort of white substance. We defined it as a silicone grease with PTFE. It is not washed off by water and terribly slippery. And now I use only her. And there is no dirt to disassemble the gun.
Very interesting. I use MAXILUBE 2000 which is a Silicone Lubricant sealant, but only ever use it on all the O-rings. I still use 5W Fork oil in conjunction with it.
 

floatingbeatle

Well-Known Member
Nov 12, 2013
39
6
48
60
East Ballina
I recently acquired an old Sten 84cm which needed a lot of rebuilding. Through one thing and another, I had to assemble and disassemble the gun several times. Each time I would put in the recommended 30cc of oil that was clearish, but when I had to empty the gun, the oil was a very grey looking colour. Would this be from the O-rings? The gun was thoroughly washed with detergent and rinsed and dried on first dismantle.
 

ECK

Well-Known Member
Jan 4, 2014
61
17
48
63
The early production "Airbalete" used grease, but in order to keep corrosion at bay inside the gun they switched back to using oil as unlike grease it continually moves around inside the gun.
Not yet sorted his Airbalete after last season. It will be necessary to see. Honestly, Airbalete is not good friends with seawater. When I bought it, I had to do some stainless steel parts again. And after each hunt, I bathe him in fresh water.
 

ECK

Well-Known Member
Jan 4, 2014
61
17
48
63
I recently acquired an old Sten 84cm which needed a lot of rebuilding. Through one thing and another, I had to assemble and disassemble the gun several times. Each time I would put in the recommended 30cc of oil that was clearish, but when I had to empty the gun, the oil was a very grey looking colour. Would this be from the O-rings? The gun was thoroughly washed with detergent and rinsed and dried on first dismantle.
When changing the oil you need to be very careful if you do not know the old oil. In a new type of oil you need to put a ring (O-ring) and hold it for a day. Then watch how everything looks. If the ring has not changed its size, does not get your fingers dirty, then you can use this oil.
 
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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,443
778
153
Australia
Water in the oil will make it go milky, particulates from wear and corrosion will make it go grey, particularly aluminium oxide. When rebuilding a gun it is necessary to pull a rag through the inner barrel and tank tubes to get everything out. All the plastic parts should be washed in warm soapy water and then thoroughly rinsed and left to dry. Ditto for all the metal parts. Motorcycle fork oil gives no problems and can be purchased in any auto spares shop.
 
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