Yong Heng crashed today..."crack...rattle...rattle...HMMMMMM" I turned it off.

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Hepotter

Hepotter

Member
Jun 25, 2015
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Toad Suck, AR
I'll take it apart tomorrow but I already know the first and second stage piston have failed. Earlier posts stated Yong Heng knew about this and have since produced stronger pistons. I'll take a chance and order the repair parts. The two year warranty is a joke!!! I tried three times to message the seller and no response at all. Today I sent a message to Yong Heng's distributor in China. I have very very little hope of relief. Fortunately, repair parts are cheap, but how many times do we have to repair the dang thing???



Regards,

Uncle Hoot 


 
You have to determine whether it's an electrical or mechanical gremlin. You say that it shut down like it overloaded or overheated. It may do that if the power supply is not sufficient. do you use an extension cord? When you say that now it won't go higher than 500 psi, do you mean it will keep running and stop building pressure at 500, or that it shuts down when it reaches 500 psi? If it's the former, it could be the check valve between the low and high-pressure chambers. There's a spare O-ring in the supplied kit. If it's an auto-shutoff model, disconnect the gauge wire and run without it. If it's not that, you will need to pull it down. I doubt that it's a broken piston as it would rattle or blow oil out of the fill hole or both if it was either them and it hasn't done enough work to have worn the rings out. These things aren't very complicated, start with the easy and symptom-related fixes first. It could be just a leaking fitting somewhere in the loop. Good luck.
 
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The temperature gauge only loosely gives the temperature of the high pressure head. It says nothing about the low pressure head or crank assembly temperature and running the thing at max temperature for thirty minutes has to be hard on it. I would agree with these guys on the troubleshooting. If you are not using an extension cord, there are no leaks in the system, the burst disk and gauge are good then it could be the o-ring on the high pressure check valve. It is under the stainless high output line on the output block. I overheated my YH to 90+deg C several times and in the end destroyed my check valve o-ring. It was easy to replace and the unit werqed great again after I did so. I wish you luck in you endeavor.
 
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Have you tested for leaks at fittings and burst disk?
Click to expand...



Man...I wish I was intelligent, sometimes!

No, I didn't test for leaks, it was the result of a loose connection on a QD fitting on the in-line filter cartridge. Wow, did I ever feel relieved and ignorant. I found it by accident when I felt the air blowing against my arm when I was trying to determine why the compressor sounded completely normal while running, but couldn't get pressure up. Who knew a simple tiny leak could keep the pressure down...the Trouble-shooting section of the owner's manual made no mention of this...not that the owner's guide is all that inclusive with instructions.

Today's lesson is don't run the Yong Heng 30 minutes non-stop, regardless of what the temp gauge shows you, 15 minutes tops...then a complete unit cool down period!!! That gauge only shows the temperature of the high pressure chamber as mentioned above. There are other parts that don't enjoy long run times, even though the instruction book says 50 minutes max run time.

Regards fellow compressorites, and many thanks for the critical advice, resources, and information!

Kindly 'Ol Uncle Hoot



PS: I also learned NOT to use an extension cord!!! Even though it was a heavy duty 12 gauge cord I used for an electrical concrete mixer...this compressor got that cord very hot. Now I plug the YH directly into the outlet...(probably burn down the damn house next!) On the positive side, I sat there and watched that little rascal get a 6.8L CF tank up to 2000 psi before my brain stated functioning and I shut it down. Now I know to do it slowly in stages. Once filled it will only need occasional top offs...a lot easier on the compressor from then on!!!!
 
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If that cord was really 12 gauge, it is the same wire size as the wiring in the house to the outlet on a 20 amp circuit. So it will heat the house wiring as well. Wire heating is from I squared R, so peaky loads cause extra heating in the wiring from the squared term.

I think we're learning, from the inability of 3000 watt 120 V generators to run the YH, and the heating of heavy 120V cords, that the Yong Heng is drawing HIGH peak currents even though it is 15-20 amps average. This current peaking is from the stacked compression stages. It is like a one cylinder engine with a light flywheel.

The YH was designed for 240V where this current peak is reduced and more power is available. Converting it to 120V creates this problem. Due to these high current peaks it should really be used on a 30A 120V circuit minimum. Limiting the runtime also limits the heating of the house wiring.
 
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Has anyone had problems with their high pressure hose leaking air while running at the solid block where the black knob is located?

I can't tighten mine enough to get it to stop bleeding air from the bottom of the solid aluminum block vent hole. I've tightened up the brass nut and the black valve to max value.

I can see there is some kind of white nylon(?) bushing with a small hole in the middle where the black knob seems to push against it to shut off air, but it isn't working. do I need to replace the tiny nylon bushing/washer inside the screw hole of the black knob...if so how???

I can't seem to get above 1500 psi with this leak and frustration is growing day by day. I spent six hours yesterday and got my 6.8L tank up to about 1500 psi. My temperature gauge fell apart and I had to remove the housing and find all the parts. Finally got them, put them back together and glued the case shut, but this leak has me at a dead stop.

I could plug it and use the fill line relief valve on the 6.8L fill hose to relieve the pressure...but is there a correct way to fix tis demon from hell?

Contact with the Ebay seller has been a lot like talking to God...lots of memos, no responses!!! Has anyone had this problem?



Kindly 'Ol Uncle Hoot
 
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It sounds like you've overtightened and damaged the seat. It should be only tightened enough to seal, if you crank on it you will ruin the seat. I have not looked inside mine, but I assume that the relief screw seals against the nylon washer that also seals the brass plug. It should be as simple as replacing that washer-gasket with a spare from your kit. Just remove the brass plug to get access to it. If somehow you have damaged the relief screw or stripped the thread on the plug, you can get a new one from here for about a buck and a half. https://www.aliexpress.com/item/32846679999.html?spm=a2g0o.detail.1000014.45.56354758DpT9Zk&gps-id=pcDetailBottomMoreOtherSeller&scm=1007.13338.146400.0&scm_id=1007.13338.146400.0&scm-url=1007.13338.146400.0&pvid=dee50aaa-7dd3-4194-b221-a18470fb5e35 Blocking the hole with an M10x1 mm bolt or plug will work while you wait for parts. Are you absolutely sure that this is where the leak is? You said before that it was coming from the filter connection.
 
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I can't tighten mine enough to get it to stop bleeding air from the bottom of the solid aluminum block vent hole. I've tightened up the brass nut and the black valve to max value.

I can see there is some kind of white nylon(?) bushing with a small hole in the middle where the black knob seems to push against it to shut off air, but it isn't working. do I need to replace the tiny nylon bushing/washer inside the screw hole of the black knob...if so how???
Click to expand...

It is likely that you have over tighten the valve resulting in the hole at the middle of the white plastic washer enlarged to the point where it no longer seals effectively. What you need to do is replacing that washer. Spares should be available in the rebuild kit that came with the compressor. The washer is just pushed in but it won't drop out by itself. Try to take it out with a treezer. It didn't work in my case and the method I used is cutting the washer in two halves with a soldering iron. A hot flat-head screw driver should do as well.
 
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