I replaced the piston in my yong heng since it wouldn't get over 250 bar when filling my tank. With the new piston the compressor shuts off near 250 bar. The breaker is not tripping and I don't have an auto shutoff model. What can I check?
yong heng shuts off after piston replacement
- Thread starter rong1966
- Start date
If you shut it off drain it and start it again it goes up to 250 again and stops or is the motor getting hot shutting off and restarting which could be a motor or overheat protector if it has one
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Is it struggling before it shuts off? What is the temp when it shuts off. How hot does the motor feel?
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It definitely sounds different before it shuts off. The temp was never higher than 50 degrees and the compressor only runs for a short time. I haven't checked if the motor gets hot.
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get a new one it’s already done it’s time. The motor could be shot. I’d check amp draw and check against the tag. Honestly as a tech I’d just say toss it and buy a new one they’re cheap enough.Upvote 0
You are probably right, but why deny a brother the potential fun/misery that is YoungHeng troubleshooting and repair? I feel that this is an important right of passage, and should be suffered by all PCP enthusiasts …
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lol ok, y’all are a glutton for punishment. Anything that looks at me funny gets sold or trashed
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The Yong Heng Auto Stop model is preset at the factory to shut off @ 3,000 psi, owner can't change. Has your YH ever gone over 250 bar? WM
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Thanks for the responses. The compressor is 2.5 years old with 6 hours run time. It is the hardcase model with no auto stop. When new it would fill a scott 45 minute tank from 200 to 300 bar in 12 minutes. The last time it was able to fill to 300 bar it took 20 minutes and the last three times it only got to 275 twice and the last time only got to 250. I was also chasing leaks every time I used it. I will try to repair it if it is something easy and cheap, but I am not going to sink a lot of money into it.
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I also wanted to mention that I ran the compressor for 15 minutes under no load and it did not shut off.
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I'd run a pressure leak test with one of these. Insert in fill whip end, pressurize, shut off and check full system for leaks with soapy spray bottle. Release pressure before re-starting compressor. WM 
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I tried that and had no leaks. I just ran the compressor again and it ran for a couple of minutes before tripping the house breaker when it reached approximately 230 bar. Maybe the new piston has to wear or settle in some more? Also, my tank pressure is at 230 bar so the compressor didn't actually fill my tank any.
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You could try running it no load for another half hour, then try again. If the windings are starting to burn their insulation, it’s only a matter of time…
Any overheating smells from motor when running under load?
Any overheating smells from motor when running under load?
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Usual tripping of breaker due to long or undersize extension cord, old house wiring or too low rated breakers. Never heard of piston needing to break-in but have heard of authentic YH parts not fitting in cloned versions. Did replaced parts look the same? Metal authentic YH compressor ID plate should have YongyIheng Pneumatic Company listed as manufacturer (pictured). WM
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I don't use an extension cord and the only time the compressor has tripped the breaker previously was during the 100 degree weather we had last year. It's a real yong heng and the new piston is almost identical to the original. I will say that the old piston did not look as dirty or oily as ones I have seen on the internet. Could there be another thing to check why my compressor won't go past 250 bar? I have checked for leaks this time and can't find any.
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If you do get a new one , keep the old one for parts.
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