Yong Heng Question

[bowdude]

I recently had one of the 2nd stage piston seals go out. Replaced it & now it will build pressure to around 3500psi then start loosing pressure. Can’t find a leak when it running. But it also sound like it’s in a bind starting around 3300psi, then at 3500psi it stars loosing pressure. Any ideas on what to look for?? Gonna tear it back some later this evening & see if I can see any thing. 

 

[bowdude]

Another thing I just noticed is that the stainless line coming out of the 2nd stage is discolored by heat. 

 

[Scotty1]

What kind of oil are you using? What did the second stage look like?

 

[Long_Gun_Dallas]

Can you detect any external leaks? Maybe you can hook a tank up that is full and pressurize the lines so you can listen for one? 

 

[biohazardman]

If I was positive there were no leaks elsewhere. First would run the compressor up to the highest pressure it will go and then shut it off without purging and look/listen for leaks once more. 

Then I would check the check valves one in the high pressure line fitting below the burst disc and the other in the larger line on the top of the first stage cylinder.

Loose both ends of the lines before you try to remove them.

After that I would try the reed valves because after the unit is run for many hours they can get some crud built up on them, from the oil you use, and then not seal completely.

But before I did that I would run it a couple of times for a few minutes to seat the new second stage rings good.

Sambo Cotton makes some very in depth and good videos of werqing on the compressor. You just need to wade through them to find what you need.

https://duckduckgo.com/?t=ffab&q=yong+heng+sambo+cotton&atb=v312-3&iax=videos&ia=videos&iai=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DYjsBcKSVeGk&pn=1

 

[Saltlake58]

If you have a line discolored by heat, check the dowdy seals at the hot point. They may have melted. I've replaced the seals in my compressor uncountable times. I keep wrenches two wrenches needed to replace them by the compressor at all times. Got it down to an art.

when it starts losing pressure, just hold your hand a few inches away from the place where the pipe connects to the compressor. If there's lots of air blowing it's probably the seal. There should be a couple spares in your YH bag of spare parts. I bought another 50 pack and have gone through quite a few of them.

 

[bowdude]

I found a small leak at the 2nd stage discharge line. I hooked my bottle up & opens the valve. Found the leak & a bad oring at the check valve. I haven’t ran yet. Got busy with other things. I’ll check it tomorrow. 

 

[bowdude]

Went back through this thing & I believe I had the top reed in backwards, now it doesn’t loose pressure but it want build past 3100. When it hits 3100 that’s it, I let run for about 4 minutes at 3100 then just turned it off cause it wasn’t going any higher. Didn’t bleed the system for 10 minutes & it held the 3100 till I bled it off. So I’m kinda stuck on what to do now. 

 

[bowdude]

Also there seems to be a lot of oil on the inside of the 1st stage cylinder wall & on top of the piston. But the oil control ring seems fine & right in the bore. 

 

[bowdude]

Got this thing fixed finally. Turned out I had install the the 2nd stage reed valve wrong. Finally found a video of a guy putting the 2md stage head together for reference. Got it together & turned it on, at 4k psi I turned it off.