GTA
Support Equipment For PCP/HPA/CO2 and springers ,rams => Support Equipment For PCP/HPA/CO2 => Topic started by: kcatx on August 23, 2018, 08:58:53 PM
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All was well-- until it wasn't. My Vevor/whatever model it is was working fine until recently-- now it will slowly go up to 2000 psi, then down to 1800 psi and stay there. What does this suggest? I assume it means a piston oring or similar. Any educated guesses?
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Check for any leak first before doing anything drastic. Also check the burst disk.
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I've been using some leak detector spray pretty liberally looking for leaks. The burst disk is ok as well (blew that as soon as I got it!).
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If you have mechanical skills then time for an overhaul. You can search for utube videos for help.
Otherwise time to buy a new one. Or if you have the budget get the latest twin pistons like the Hatsan lightning. $200 vs $1300. Your choice.
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Probably a worn out second stage piston seal. Did your compressor come with some spares?
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before changing the second stage seals,, watch this video first
https://youtu.be/a7T_4zrgXnc
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I did a teardown yesterday-- only thing I didn't do was change the seal on the top of the piston-- I'll do that if it's not working properly when I next test it (tonight hopefully). I needed to use some RVA to create a bottom gasket as mine was broken when I removed it (I believe when I disassembled it it broke).
My second stage seal was ok.
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I did a teardown yesterday-- only thing I didn't do was change the seal on the top of the piston-- I'll do that if it's not working properly when I next test it (tonight hopefully). I needed to use some RVA to create a bottom gasket as mine was broken when I removed it (I believe when I disassembled it it broke).
My second stage seal was ok.
i think all you have to do is clean that check valve metal plate with the small hole
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The guy does a good job on the Vevor but what about a "genuine Yong Heng unit"My unit is taking longer and longer to fill my gun any videos out ther for YH compressors?
Thanks Dave M
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There are all kinds of youtube videos on the Yong Heng but only a couple that get very deep into the repair end of things and none that I've found so far that deal with changing the second stage seals on the upper piston rod.
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The guy does a good job on the Vevor but what about a "genuine Yong Heng unit"My unit is taking longer and longer to fill my gun any videos out ther for YH compressors?
Thanks Dave M
how many hours do you have on yours, real time or estimate ?
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I found this last night but hadn't had time to post it up here till now. https://www.youtube.com/watch?v=TpCX-GFQC7w (https://www.youtube.com/watch?v=TpCX-GFQC7w) This guy shows how easy it is to change second stage seals. This is a link to get new seals https://www.aliexpress.com/item/Two-stage-piston-ring-Sealing-ring-piston-ring-5-piece-lot/32691690417.html?spm=2114.10010108.1000013.3.293a5cc6aiJcXh&scm=1007.13339.90158.0&scm_id=1007.13339.90158.0&scm-url=1007.13339.90158.0&pvid=88a21f04-7997-40f2-bbb1-bf64f32efd6e&_t=pvid:88a21f04-7997-40f2-bbb1-bf64f32efd6e,scm-url:1007.13339.90158.0 (https://www.aliexpress.com/item/Two-stage-piston-ring-Sealing-ring-piston-ring-5-piece-lot/32691690417.html?spm=2114.10010108.1000013.3.293a5cc6aiJcXh&scm=1007.13339.90158.0&scm_id=1007.13339.90158.0&scm-url=1007.13339.90158.0&pvid=88a21f04-7997-40f2-bbb1-bf64f32efd6e&_t=pvid:88a21f04-7997-40f2-bbb1-bf64f32efd6e,scm-url:1007.13339.90158.0)
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All fixed. went from 3800psi to 4370 or so in 10 min.
Temp is now 41.x and stable- much better than before. Just replaced the top oring and cleaned everything, used some RVA to replace the bottom gasket that broke when disassembled.
Cleaned check both check valves.
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I have a compressor coming this weekend. I have been hearing all these horror stories about these units. But most & I say most
are cleaning out passages or broken seals ect. I hope when mine comes in every thing will be ok. But before I start yelling the Sky
is falling, if I do have some problems, I plan to try & keep it clean & maintain it. I have a very hard time shelling out a $1000 or
more on a compressor.
JMOHOP Fly :D
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I also have to note since cleaning it out my temps never went above 46F now, which is an improvement.
I had planned on buying a Hatsan Lightning soon, now I may hold off. I wish I had a reasonable method for doing an auto-purge of the bleed valves.
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Just watched the mod videos noted from above. Seems the guy was thinking that there was mechanical interference on the high side piston top since he removed a few thousandths material from the top of the piston. This would solve the piston breakage problem only if the issue is actually a hard mechanical interference between the piston and the head. Hard mechanical interference should show up as damage to the head or the stainless steel "washer" that serves as a check valve and he did not note any such damage. Seems to me that the 4.5k pressure on the top of that high side piston pressing on the center of the low side piston (which seems pretty thin) is more likely the cause of the failure than is an actual hard mechanical interference. A true hard mechanical interference would seem likely to stop the rotation of the mechanism. If he is right then the mod is a good solution to the problem but my instinct says it is probably pressure related and not mechanical interference related. For anyone thinking of doing this I would suggest just removing the head and checking the clearance at the top of the piston with some automotive plastigage to be certain there is a mechanical interference before removing any material.
Do note the recent post noting a large failure of a YH clone. Seems either the connecting rod froze to the wrist pin in the low side piston or the black low side cylinder failed. No injury was noted but it did separate the parts pretty badly and injury could have happened. I do have and use a Tuxing and YH version of these small compressors but I only fill guns directly with them to 3k. I do plan to buy a more robust compressor in the future. Be safe with such high pressure.
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The guy does a good job on the Vevor but what about a "genuine Yong Heng unit"My unit is taking longer and longer to fill my gun any videos out ther for YH compressors?
Thanks Dave M
how many hours do you have on yours, real time or estimate ?
GenDoc, I have less .5 hours
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The failure was either the connecting rod small end or the low pressure cylinder.. I just took it apart a few hours ago.. Most of the small end of the connecting rod is still on the wrist pin and is not seized or any signs of galling, bright and no scoring or damage to the wrist pin.. After taking a good look at it I believe it was a bad casting defect in the cylinder.. Wondering if clones are built from rejected seconds .. Also most compressors are manufactured in the same company in China.. Ordered new cylinder and piston, connecting rod from Tuxing.. ( my clone is of a Tuxing )
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Probably a worn out second stage piston seal. Did your compressor come with some spares?
Where do I get that black 2nd stage piston from? Any links?
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check the listing I posted here.
https://www.gatewaytoairguns.org/GTA/index.php?topic=147932.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=147932.0)