yong heng shuts off after piston replacement
- Thread starter rong1966
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Same happened to me twice. Found leaking "O" ring in quick-disconnect fitting in first case, second, failed gauge started leaking. Tore into compressor first time, without doing dead-head pressure test, nothing found, cost me a new gasket. Dead-head test eventually found problem in both cases. Now, when pressure build seems slowing, dead-head test is done first. WM
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There are "shims" the align the connecting rod to the crankshaft. Did you replace them in the same order?
I have 2 yong heng compressors, 1 model like yours and 1 of the newer auto shut off model. I've had them both apart more than I can remember. Both function correctly. Without knowing exactly how you replaced the piston , I can't really help you.
I would suggest you take it apart again and really examine the second stage rings and your reed valves.
Right of passage.
I have 2 yong heng compressors, 1 model like yours and 1 of the newer auto shut off model. I've had them both apart more than I can remember. Both function correctly. Without knowing exactly how you replaced the piston , I can't really help you.
I would suggest you take it apart again and really examine the second stage rings and your reed valves.
Right of passage.
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No. Should I and if so with what? I have to amend my previous post, I checked for leaks again with soapy water and found two. Ran the compressor again and it did not trip the house breaker but it did shut off. Having trouble stopping the leaks--connection at top of low pressure block and connection at top of high pressure which has leaked before.
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I took the plastic shims from the old piston; instead of one on either side of the piston they were both on the motor side and that is how I placed them on the new piston.
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I'm thinking that you have the piston rings installed on the piston upside down. The piston rings on the big 1st stage (low pressure) piston have a taper to them. The proper taper should be like this \_____/ . I think the idea here is that, during the down stroke, oil is pushed against the cylinder wall and a tiny bit of oil will get past the ring intentionally by design (the compressor is designed to use some oil). Then during the up stroke, the cylinder wall is lubed and the taper doesn't let any air or oil go back down into the crank case. If you have the piston taper wrong like this /_____\ then the taper is trying to keep oil from going into the cylinder. That could mean a lot of friction and lack of pressure in the cylinder also.
stovepipe
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Don't know which direction the first stage rings are; they were already on the piston when I got it. I took a look at the old piston and the bottom ring is different from the upper two--it is split and almost looks like two rings. I don't recall if the new piston was similar.
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I wish I could find the place where I found that info last year -- I probably won't be able to find it again. At that time I had just pulled the piston from my YH and came across a post/article or something by someone who bought a new piston with the rings already installed, but the top two rings were upside down and were causing a problem -- I think the same problem you are experiencing. I didn't even know there was a taper to the top two rings (it's pretty subtle), but I looked very closely at my rings and saw the taper and mine were correct (I wasn't having a problem -- was just trying to prevent one). The botton ring is not a compression ring, so I don't think the orientation of it matters.
stovepipe
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Yes, always lubricate with the same oil used in the crankcase. It takes time for splash lubrication to get lube in the piston area.
Another thing it's extremely important not to put to much lube in the crankcase.
Check the upper stage head bolts and see if they are tight, oring might be allowing undetectable during operation.
Open it up after checking all head bolts for equal torque. Sorry , I don't have the torque specs.
You'll find the problem , keep looking.
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I assume to just lube the lower large piston chamber and not the smaller high pressure area?
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I'm replying to my own post to clarify what the "taper" looks like. It's not a smooth taper -- not like a beveled edge. It's more like a step -- two different diameters on the edge of the ring. The larger diameter of the ring should be closer to the top of the piston.
stovepipe
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I lubed the upper cylinder with a small amount of silicone oil, just so it didn’t start out dry. I had no problems with it running after that.
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