YONG HENG AIR LEAK

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SilentSquirrel

SilentSquirrel

Member
Jun 1, 2019
1,263
515
The other Washington, United States
Hello

I have an air leak on my Yon Heng compressor

It comes from around the threads on the brass valve body that the Pressure Relief Screw screws into

Looking into the orifice I've seen no seals or O rings

Should there be any in there?

Here is a picture of the part

It s the brass one

https://www.aliexpress.com/item/32846679999.html?spm=a2g0o.productlist.0.0.4bc71b5fHWPzWi&algo_pvid=7be64169-dfc9-4948-b3fb-f0ad62777c05&algo_expid=7be64169-dfc9-4948-b3fb-f0ad62777c05-0&btsid=8f9cbf0e-e4f8-41a4-bd2d-36fd1d418765&ws_ab_test=searchweb0_0,searchweb201602_9,searchweb201603_55

Ed

PS

I've tried grey teflon tape, as well as a compression washer around the valve body
 
There should be a white Delrin seal under the brass piece. If the seal is not there you should have one in the spare parts kit that came with your compressor. If the seal is there you should be able to tighten the brass nut down a little more to stop the leak.
Click to expand...

They dont use o ring to seal. They used white derlin washer. The compressor comes with few of them. They are white hard plastic donut looking.
Click to expand...


Thanks to both of you; bihazardman & 2fast2furious

There were no signs of a delrin washer in the hole.

I added one. (My only one)

It stopped some of the leak.

Further tightening did not help.

If fact, upon removal of the brass valve, it appears as if the delrin washer vanished from the hole.

Have also verified there is no cross threading.

The brass valve will go all the way to touching the delrin washer by hand

I'm taking an anti frustration break
 
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I doubt if the original seal has really vanished because if it was not there, the whole valve should have failed to function and air should have escaped through the bleed hole instead of the thread of the brass body. The color of the original seal is close to that of anodized aluminum. With some dirt on the top, it's presence may not be very visible. I would suggest you to check again and replace it with the spare seal in the rebuild kit that came with Yong Heng. The material is harder than delrin and the hole is smaller than that on a delrin seal. I have tried using delrin seal at this location and it didn't work. 
 
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.... I reinstalled the valve with grey teflon tape; and the leak has stopped.
Click to expand...

The picture below shows the inside of the bleed valve on my Yong Heng with the original plastic washer in place. The plastic washer seals at two points : around it's perimeter and the center. The thread of the brass body or that of the screw going through it does NOT do any sealing. If air is leaking via the threads then air must be going into the small chamber inside the valve via the paths shown by the yellow arrows in the picture below. If air cannot esacpe via the threads due to being blocked by teflon tape, it will do so via the bleed hole at the bottom of the block so the leakage problem should still be there. The solution is to replace the seal. 

1571412572_11296659815da9da5c105986.22018877_Capture.JPG



 
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The white seal that I installed had an OD large enough that it did not slide into the bore without resistance but needed to be tapped into place.to get past the threads and into place

Is that the correct seal?
Click to expand...

Yes, the fitting is quite tight but the key difference between the seal for the valve and those for other fittings is the size of the hole. It is much smaller on the seal for the valve. If this hole is too big, the screw will go through it making sealing unachievable. In the picture below, the left one is the seal for the valve, the right one is for other fittings 

1571465707_1864324635daaa9eb431d17.72400369_x (2).jpg

 
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The white seal that I installed had an OD large enough that it did not slide into the bore without resistance but needed to be tapped into place.to get past the threads and into place

Is that the correct seal?
Click to expand...

Yes, the fitting is quite tight but the key difference between the seal for the valve and those for other fittings is the size of the hole. It is much smaller on the seal for the valve. If this hole is too big, the screw will go through it making sealing unachievable. In the picture below, the left one is the seal for the valve, the right one is for other fittings 

1571465707_1864324635daaa9eb431d17.72400369_x (2).jpg
Click to expand...


Hello airgunfans

Thanks again for your help & advice.

As mentioned earlier I do have some of the correct seal (left picture/small hole) on the way to me as part of a Yong Heng O-Ring set.

Do you know where the seals can be bought without purchasing the complete set of O-rings?

My Ali-eBAy-Google-Amazon searches have come up empty

Ed
 
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Do you know where the seals can be bought without purchasing the complete set of O-rings?
Click to expand...

I am located in Hong Kong and I buy all my Yong Heng stuff from their official on-line shop in China. They are very flexible here but outside China you probably need to buy the whole set. You will need to use those green O rings ( circled in red below ) in the package after about 6 ~ 7 hours of run time so there will not be much wastage. Those white plastic seal do not wear out much as long as you do not over tighten the valve so you do not need to keep a lot of spares.

1571623005_17180604905dad105d9a6c58.53235743_Capture.JPG

 
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Do you know where the seals can be bought without purchasing the complete set of O-rings?
Click to expand...

I am located in Hong Kong and I buy all my Yong Heng stuff from their official on-line shop in China. They are very flexible here but outside China you probably need to buy the whole set. You will need to use those green O rings ( circled in red below ) in the package after about 6 ~ 7 hours of run time so there will not be much wastage. Those white plastic seal do not wear out much as long as you do not over tighten the valve so you do not need to keep a lot of spares.

1571623005_17180604905dad105d9a6c58.53235743_Capture.JPG
Click to expand...


Thank you for the reply airgunfans

You are correct.

Purchasing from the US requires buying the entire kit

Where are the green O-rings employed in the compressor?

And a more grand question

Is it possible to find a parts diagram for the machines?

Ed


 
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Here are the locations of the seals in the rebuilt kit : 

1571632510_1182352685dad357ea0d5a1.17667561_Capture.JPG


I haven't come across any parts diagrams for the compressor but as the construction of the machine is very simple, you can kind of get it after taking it apart several times. There are multiple Youtube videos on the subject.
Click to expand...


PERFECT!!

Thank you very much

I'm sure others will find this useful also



Ed
 
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