Tuning How can I fix a bad valve?

[Savagefox]

I got a bad valve on mi PP800, send back to repair, turned back the same...

All seems ok, but if I shoot, the weapon starts loosing air and get empty in about 2/3 hours, I dismout it 3 times, the first I see a ton of debris and dirt inside the cilinder so I wash it carefully, it hold a little better the air, but same result.

Second Time I oil slightly the insides with silicone (I know is not advisable), same result.. the 3rd time I wash and dry it all, but didn't work. I supose that the debris caused little irregularities on the valve or something and is just F**** up.

The spares are out of stock right now and are pretty exprensive for what it is.

This is the valve disasembled, I wonder if I can try to roll a tiny cape of teflon tape, or maybe melt some plastic or wathever that creates a cape.

I also got a 3d printer, the plastics are not prepared to hold high pressures and are porous on microscopic level, but they can be heat/solvent treated to solidify better... Is there any common solution?

 

[Enkey]

Hi

It is difficult if you have small irregularities, try with 1800 sandpaper if it is broken you have nothing to lose, you will have to look at the valve and the seat

Regards 

Enkey 

 

[Odoyle]

Go to the hardware store and bring that spring and match a same diameter but a little weaker springiness and longer is better cut it a little longer than the factory spring heat that cut end on the stove or torch flame till red then press down on a smooth flat surface like a countertop.

You need to use divers silicone grease it has the consistency like Vaseline.

 

[Savagefox]

So.. you think the problem is in the spring? why?

 

[Odoyle]

Maybe not allow the valve to be all the way sealed causing your leak.

 

[Savagefox]

Well, the second time I play a little with the spring to augment the lengt to do more pressure, cause sometimes it holds well the pressure untill you make a shot.

Also, today a dissasemble it again and I notify a little circle of tiny rust like dirt, pass a cutip and its definitelly dirt in there, but very little. I clean up the cilinder 3 frikin times, even pour boiling water the 3rd.

I also checked my filling pump, a cheap chinesse one, but the filter is perfectly clean.



Is that very tiny layer of rusty-like debris on the operation margin? can this be the cause of the leak? so I must apply a tratment to the cilinder or something?



Hipotesis 1- Tiny particles of poop appeared from somewhere got stuck on the valve and cause the leak, thats why before cleaned usually didn't leak untill the first shot.

Hipotesis 2- The valve seats incorrectly due to small deformations or... spring? (can it really do that?)



Sometimes I shot and it corrects the leak... so it may be taht the valve is seated correctly, or that the debris causing the leak goes out untill it acumulates again.



I got tempted this morning to trow the damn thing towards the wall.

 

[Raden1942]

Did you tear apart the regulator and everything? That debris is coming from somewhere. I suspect debris is getting in between the top hat where it seats. Hard to say for sure but I've had guns where a part broke and it wasn't obvious what was wrong but debris was everywhere. I recommend a full tear down clean and reassembly. Sorry I couldn't be more helpful without looking at it myself it's a mystery. 

 

[Vetmx]

You’re going to have to try to burnish it. That’s the last hope to save a poppet unless you have a lathe. 

 

[biohazardman]

If you clean the surfaces that seal on the poppet and valve body then you can apply some type of polishing compound or polishing toothpaste to the sealing surfaces of the valve and poppet. Assemble it and carefully put the valve stem in a drill chuck. Spin it at a low speed for a 10-15 seconds. Not to long or too fast as you can melt the seal. That will mate the surfaces and take out imperfections at the same time. It may take a little longer if there is much surface damage or your polishing compound is too fine.

I have done this many times and it always werqs very well.

 

[Odoyle]

If you augment the spring won't it cant during operation thus causing the leak? 

 

[Savagefox]

Wow, thanks for all the answers.

You’re going to have to try to burnish it. That’s the last hope to save a poppet unless you have a lathe.

I will apply some heat, but for the moment I won't make anything that I could regret.

Did you tear apart the regulator and everything? That debris is coming from somewhere. I suspect debris is getting in between the top hat where it seats. Hard to say for sure but I've had guns where a part broke and it wasn't obvious what was wrong but debris was everywhere. I recommend a full tear down clean and reassembly. Sorry I couldn't be more helpful without looking at it myself it's a mystery.

There is no regulator on the PP800, is a cheap gun and there is very little that can break unnoticed, if thats the problem my bet would go for a inner tube corrosion or something, but that doesn't look like either.

If you clean the surfaces that seal on the poppet and valve body then you can apply some type of polishing compound or polishing toothpaste to the sealing surfaces of the valve and poppet. Assemble it and carefully put the valve stem in a drill chuck. Spin it at a low speed for a 10-15 seconds. Not to long or too fast as you can melt the seal. That will mate the surfaces and take out imperfections at the same time. It may take a little longer if there is much surface damage or your polishing compound is too fine.

I have done this many times and it always werqs very well.

I got a mini-dremel that I used to tune the ports (its not what it caused it, the gun has already leaking from the start) I could try to attack the pin to it and make it rotate against de the seal, thats a great idea.

If you augment the spring won't it cant during operation thus causing the leak?

From the start the gun has this problem, everything ok until I shot it.





I'm gonna rotate the pin against the seal with a low power mini-dremel from the other side, could I use a ceramic based oil or better nothing? (is recomended to metal against metal and for the barrel of firearms)

Y will also apply some heat to the plastic part, I think sandpaper is something that I could regret, better not for the moment.

For treating the inner tube, I only have a regular black spray of acrylic/butilic paint, can that be any good to restore the insides of the cilinder, or even to cover the pin and the hat with a layer of something?

 

[biohazardman]

savagefox

If you augment the spring won't it cant during operation thus causing the leak?

It seems to werq on Crosman valves without spring damage and I did it often when building my valves as Crosman kept sending me junk parts that would not seal. So I took up this practice and it took care of the imperfections on the valve body and the poppet seal for the most part. I left some play by not tightening the valve cap on all the way so as to let the poppet spin on the spring as freely as I could. Guess I should have said that earlier but now is good too.

 

[Parrotculler]

I had the exact same issue with the PP800 and feel your pain. It started when I put a regulator into the gun. As a consequence the pressure closing the valve became 120 bar instead of 200. The slight imperfection on the poppet or on the valve seat became a problem because the valve was not pressed shut as strongly anymore.

5 suggestions:

- make sure the valve is not dry but is lubed with silicon spray. The oil film helps the seal.

- apply Odoyle's stronger valve spring or, easier, shim your spring with a pvc washer or two. This increases the preload and the seal. No cant because the valve seat and poppet are conical.

- polish the seat with a cotton dremel bit with some 0.5 grain polishing compound.

- look at the poppet under a strong magnifying glass. If you see a streak, polish it out with very fine steel wool covered in .5 polishing compound or at least silione oil. Do not apply heat, you will destroy it.

- worst case, get the cheapest artemis cp1 or cp2 co2 gun (60 bucks) and scavenge the valve housing + valve stem. (And other parts, e.g. cocking lever -- but not the barrel because it is too short.,) They are the same except for the inlet cap -- re- use your existing one-- it fits. This is what I ended up doing. Never looked back.Gun holds its air for months.

The good news: with the Lane regulator and some polishing this is an incredibly accurate gun even at 50m with the JSB Jumbos 5.51. I hunt pigeons with it. Good luck.

 

[Odoyle]

I would try a little weaker but a little longer length spring.

 

[Vetmx]

When I said burnish it, I was talking about what biohazardman later described. I just didn’t have time to explain because I was headed out to eat. Don’t heat it or “burn” it.

 

[Savagefox]

I had the exact same issue with the PP800 and feel your pain. It started when I put a regulator into the gun. As a consequence the pressure closing the valve became 120 bar instead of 200. The slight imperfection on the poppet or on the valve seat became a problem because the valve was not pressed shut as strongly anymore.

5 suggestions:

- make sure the valve is not dry but is lubed with silicon spray. The oil film helps the seal.

- apply Odoyle's stronger valve spring or, easier, shim your spring with a pvc washer or two. This increases the preload and the seal. No cant because the valve seat and poppet are conical.

- polish the seat with a cotton dremel bit with some 0.5 grain polishing compound.

- look at the poppet under a strong magnifying glass. If you see a streak, polish it out with very fine steel wool covered in .5 polishing compound or at least silione oil. Do not apply heat, you will destroy it.

- worst case, get the cheapest artemis cp1 or cp2 co2 gun (60 bucks) and scavenge the valve housing + valve stem. (And other parts, e.g. cocking lever -- but not the barrel because it is too short.,) They are the same except for the inlet cap -- re- use your existing one-- it fits. This is what I ended up doing. Never looked back.Gun holds its air for months.

The good news: with the Lane regulator and some polishing this is an incredibly accurate gun even at 50m with the JSB Jumbos 5.51. I hunt pigeons with it. Good luck.

I do have this mini-dremel to open carefully the ports, don't even know what the white things are for before, but thanks, I'm gonna try to polish with them before rotate the pin against the valve.

I will try to 3d print a internal spring-guide wich also moves slightly forward the spring for more pressure and steadiness.

I also considered buying a SMK1 or a chaser and canibalize it, but that's much money.

When I said burnish it, I was talking about what biohazardman later described. I just didn’t have time to explain because I was headed out to eat. Don’t heat it or “burn” it.

English isn't my main language, burnish sounds like burn it to me and I make a correlation.

I'm from Spain, the only good about air-weapons here is that at least we got the maximum power legally allowed in Europe (24,2 Joules/17,8 fpe) without thousand permits, periodic obligatory weapon revisions, periodic obligatory revisions on you, wich all cost money.. etc... the ''big brother'' likes to keep an eye on his armed citizens and difficult as much as possible that their acces to arms.



So I go for a PP800 on .177 and want to bring it as close as possible to 17 fpe just for the sake of it, and for rabbit/hare hunting on an eventual apocalipse, or more likely if things keeps geeting worse around here.

I try to ask on spanish forums, but it seems here's the only place with good advises.



I only have the doubt if I can black paint (acrylic/butilic based spray) the internals of the cilinder to protect it from rust, or by any chance that could go allahu akbar on me on high pressures... I don't think so... but its obvous that I'm not a very proficient weaponsmith.

 

[Parrotculler]

I would leave the internals of the cylinder alone. It is made of titanium. The paint is unlikely to hold and if that gets into your valve it will be a world of pain. Just spray some silicone grease into it. (By the way, SPAirguns carries the cp1 for 60Eur.)

 

[Savagefox]

https://es.aliexpress.com/item/1005001785091411.html?spm=a2g0n.order_detail.order_detail_item.3.302e39d3QWliJ0&gatewayAdapt=glo2esp

The 10 pom pin set really saved me a lot of problems, I usee both on the pp800 and the 2240 pcp ebay kit.
Almost always the problem is on the pin.