Gamo Urban leak from fill valve

[3crows]

Sorry to bother y'all once more. Been a while. I have a brand new Urban. It immediately began leaking upon the first fill from the fill port that leads to the fill poppet. I bled the rifle down and removed the entire valve assembly and replaced the large valve O-ring, 39, and the small O-ring, 29, that is accused per several videos of being the culprit. I put the dang thing back together and of course it still leaks despite new O-rings.

I suspect that the culprit is not an O-ring but the black plastic fill poppet valve Item 35. I inspected the poppet body sealing surface for the plastic poppet and see no defect. The plastic poppet has a round end that is squared off and appears to be the seat.



Any ideas as to how to proceed? I do not want to return the rifle to where I bought it because I bought it while on a trip far away. And I would rather not return it to Gamo for no telling what other damage might occur. This should be simple, I work on scuba gear and am an A&P mechanic, I understand tools, fire and how to fix things generally.

Should I try to polish the black plastic poppet seat sealing edge? Perhaps gently flame polish it in case there is a tiny burr? Or do these things need to break in and form a seal in due course? This is my first PCP, I also have a Umarex G2 on order.

Are there any USA parts sources or reliable parts sources anywhere that ship to the USA?

Thanks in advance,

James

[3crows]

Got it. So, I took it back apart and inspected the plastic poppet. In the sealing edge/face there were tiny shards of brass imbedded in several places. This was evident upon using my 10X loupe. I guess I need new glasses or a brighter light because once I saw them with the loupe I could see them naked eye. I carefully polished them out using 600 and then 1000 wet-dry paper (wet), hit it with a flame and then buffed the face on a smooth steel surface. No leakage now. Holding tight after several cycles. Fingers crossed.

I think I will order a couple of those poppets if I can find a good Gamo parts source.

Thanks,
James

[kbstingwing]

Glad to hear you found the problem and got it fixed.

[rkr]

Got it. So, I took it back apart and inspected the plastic poppet. In the sealing edge/face there were tiny shards of brass imbedded in several places. This was evident upon using my 10X loupe. I guess I need new glasses or a brighter light because once I saw them with the loupe I could see them naked eye. I carefully polished them out using 600 and then 1000 wet-dry paper (wet), hit it with a flame and then buffed the face on a smooth steel surface. No leakage now. Holding tight after several cycles. Fingers crossed.

I think I will order a couple of those poppets if I can find a good Gamo parts source.

Thanks,
James

Here, almost all the BSA/Gamo PCP parts you ever wanted https://www.airgunspares.com/gunspares/airgun-spares/bsa-air-rifle-models/buccaneer.html

[tcarlson777]

Nicely done 3crows! It feels great to fix your own gun. I recently fixed a POI issue with my Umarex Origin and now I enjoy shooting it even more.

[3crows]

I am happy to report that the Urban is a laser beam at 30 yards with the JSB Jumbo .22 18.13 pellets. Off my Stinger they are making a small ragged hole. It also shoots the Crosman HP 14.3 nice! I still have a teeny, tiny leak. Maybe it will settle in. It will leak off about a 1,000 psi over night, sometimes. Other times it holds tight. I ordered two new poppets and the poppet valve body and a few O-rings for spares. I am just going to replace the poppet when I get them. In the meantime it holds air, I can walk my property and dispatch deserving vermin with authority  . And from my sniper roost I have a 30 cf SCUBA tank topping/feeding it.

3C

[3crows]

Not a very good photo but it has been pretty poor to go outside much. I did get the scope sighted in. Pretty much only took two clicks down and left and it was dead on the money at 30 yards. I ran it through the chronograph and got 760 fps for the JSB 18.13 grain pellets and 850 fps with the Crosman Premier HP 14.3 grain.



I do not have time now but I would like to draw up a new front valve body that eliminates the poppet valve and just puts a Foster valve on the front and relocates the pressure gauge to the side and maybe one other optional plug for an over pressure relief. But by 396 has a plastic valve and it works fine and so do many of my SCUBA regulators so maybe just be patient and wait for the new poppets to arrive. I might be able to thread the fill probe holes and install a Foster valve and a plug, hmmmm.

I really like this little rifle and it feels like quality, considering the price especially. And it is very accurate, it is just shooting dime size groups over and over and it is quiet too. Pounding out right at 24 FPE, give or take, not bad. Enough to pulverize starlings and vaporize HOSPs and take the odd squirrel or rabbit.

3C

[rkr]

Those BSA barrels are usually rather good ones. You can check the mods for free floating the barrel and using a longer grub screw for trigger adjustment, rather popular things to do for those guns.

[CraigH]

The Urban is a fine rifle.   About the last air gun (not to 100 in house yet) I would sell if requirements involve moving to a "home".

[3crows]

Those BSA barrels are usually rather good ones. You can check the mods for free floating the barrel and using a longer grub screw for trigger adjustment, rather popular things to do for those guns.

Thanks. While I had the front valve body out I thought to remove the barrel band. It seems unneeded. So I checked to see if it was putting a preload on the barrel and this one is not so I left it be for now.

I put a left over BSA 2X7 (meant for a Ruger 1022) Sweet 22 scope on it. The little scope is very small and light. Probably not what most would use but I had it left over. Also, I ordered the CDT trigger (GRT4) and I hope it works in the rifle. I have one in my old Stoeger X20 and it really helps with a good trigger pull.

James

[3crows]

The Urban is a fine rifle.   About the last air gun (not to 100 in house yet) I would sell if requirements involve moving to a "home".

Geeeez man, a hundred air rifles! I think I have eight. I guess I need more . Unfortunately I am afflicted with the innate need to acquire those types of weapons we cannot talk about here and with Marlin coming back online I am likely to be very poor. However, I want a Marauder .25, that is my next air rifle.

I guess the thing that drew me to the Gamo Urban is that the rifle is proportionate and is like a .22 (PB) rifle in hand. It is short and light and feels natural in my arms. And it shoots good. It may be the first air rifle I have shot that can go head to head with a good .22LR rifle for accuracy. It is right in there. Dime size 10 shot groups at 30 yards, I will take that. Here is one:



James

[rkr]

Some pellet testing, better scope and trigger fix should improve those groups. Most BSA barrels can do 1/2" or smaller groups at 50 yards. My .25 shoots 1/4" groups at that range and sub 1" at 100M. Try JSB Exacts, Exact Express and Exact Heavies - they have been best in 4 out of 5 of the .22 BSA barrels I've had.  The odd one is loose and likes 5.55mm H&N FTTs. A good PCP can beat .22lrs in good conditions as the fps spread is smaller giving less vertical spread.

[3crows]

Got it. So, I took it back apart and inspected the plastic poppet. In the sealing edge/face there were tiny shards of brass imbedded in several places. This was evident upon using my 10X loupe. I guess I need new glasses or a brighter light because once I saw them with the loupe I could see them naked eye. I carefully polished them out using 600 and then 1000 wet-dry paper (wet), hit it with a flame and then buffed the face on a smooth steel surface. No leakage now. Holding tight after several cycles. Fingers crossed.

I think I will order a couple of those poppets if I can find a good Gamo parts source.

Thanks,
James

Here, almost all the BSA/Gamo PCP parts you ever wanted https://www.airgunspares.com/gunspares/airgun-spares/bsa-air-rifle-models/buccaneer.html

I did purchase some items from this source and they show shipped, great! However the next day I got a fraudulent charge to my bank card for a large amount of money. The parts purchase from the suggested place is the only recent charge I have made on the card. So beware that somebody is stealing/selling/harvesting credit card data and using the card numbers (via their PayPal).

So, again, is there any place in the United States that can provide air gun parts, specifically Gamo parts?

3C

[rkr]

Knibbs is the official spare parts place for BSA and I've used them many times in the past. Of course it could be man in the middle attack or they've been hacked. You might want to let them know about it.

[3crows]

Knibbs is the official spare parts place for BSA and I've used them many times in the past. Of course it could be man in the middle attack or they've been hacked. You might want to let them know about it.

It was not the business fault I am sure, these fraud people mine data and may have a harvesting programs on innocent websites, that mines the card data from unsuspecting website or business. The person or business is just as much a victim as the consumer (me) that had a very large charge pop up out of no where on my bank statement and from PayPal where I do not even have an account. However, PayPal to their credit within three hours of contacting them refunded my bank account and my bank closed the bank card this morning. I had not used the card in months and then a fraudulent charge so somewhere my data was mined and then used to buy something expensive. Yes, I will inform the website owner of the concern. I understand it is not their fault and hope they are not harmed.

Now that my panic attack is over from the above, I still have a small leak in the Urban. I do not see bubbles from the fill port so not sure where to look next. The rifle is useable, it is a slow leak, overnight. But, still, I need to fix it. Have parts on the way and when they get here I will tear the rifle down and dunk the air tube if needed. There really are not that many places for it to leak. I am suspicious now of the knock off valve and I have one on order.

3C

[kbstingwing]

on the leak, it may be an O-ring or the poppet, to test for the poppet remove the shroud and put a balloon or a plastic bag on the end of the barrel, seal tightly with a rubber band and make sure the breech id closed, if the balloon or bag fills with air, it is the poppet, I found you can burnish the poppet to make a proper seal with a micro fiber cloth and some light oil, put the shaft of the poppet in a cordless or corded drill, place small amount of oil on the cloth and at high speed spin the poppet, apply the cloth with good amount of pressure against the poppet sealing surface, ( make sure to have plenty of cloth between your fingers and the poppet, it will get hot), do this for about 90 seconds or until it gets very hot, then let cool, done, this should remove any micro scratches and burrs from the poppet, re-install., I had a small leak in my Brocock Bantam, and this cured the leak, it works great and been holding air for over a month now.

good luck

[3crows]

So as per my earlier posts, I did fix the copious leak from the fill valve poppet molding. But my rifle still leaked down, just more slowly. So, this morning I tore it down and found that both the front a rear main seal O-rings are totally the culprit.





It does not appear, that despite my suspicions otherwise, that the knock off valve leaks, the knock off valve appears solid and tight. The leaks are coming only from the main seals. I had replaced the front main seal with a generic O-ring from a kit because the original O-ring had a half moon divot in it. But the new O-ring is also leaking and clearly the (original part untouched) aft O-ring is as well.

I did order parts from the fine sources in the UK and I also did call Gamo Tech Support USA and they sold me some additional parts and were super nice and friendly to me and inexpensive. But she wrote down one main seal instead of two on my order, darn that . The generic O-ring seemed an excellent fit, why does it leak, thoughts please?

Well, at least now I know where it is leaking as I await my M-Rod .25 caliber that I just ordered, please do not tell my wife !

An excellent link, for the Coyote, same rifle, that was helpful to me to tear my rifle down.

https://www.airgunforum.co.uk/community/index.php?threads/a-look-inside-the-gamo-coyote.318191/

3C

[3crows]

For posterity in case somebody else has the same issues. The #57 O-ring at Ace Hardware was a perfect fit for the main seals on both ends. One odd thing, the aft valve housing has a double step and is very wide. This allowed the O-ring to be caught in the more forward (muzzle end) step and was pinched. I used a much smaller cross section O-ring to act as a pusher to keep the sealing O-ring positioned as I pushed the valve body into place. This extra O-ring just will remain inside now serving no real purpose as pressure in the cylinder should keep the sealing O-ring positioned henceforth. I also polished the inside of the cylinder in the sealing areas with 600 paper and Ballistol and then cleaned up afterwards. A bubble check revealed no bubbles, looks tight now everywhere. Fingers crossed this time for real, I think I got it . I hope so because I sure like this little Gamo Urban.

3C