Yong Heng is apart any questions?

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Rodeo

Rodeo

Member
Dec 19, 2017
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Maryland, United States
Yup, the day has finally come. My Yong Heng needs a new high pressure piston top. The screw on piece that holds the top two piston rings gave in. Knew it was going to happen eventually - lasted for 11hrs of run time. The failed part:

1593723805_14298557145efe4b9da15294.85164967.jpg


I just grabbed it with a pair of pliers to unscrew it so it is more chewed up than it was. I ordered enough parts to rebuild it twice (lower+upper piston w/ rod, gasket set, o-ring + seal set and the offending piece). Totaled $65 with tax and free shipping.

Now to the point of my post. I figured that I would offer to take any pictures, measurements or answer any questions that I can while I have it apart. I do have to forewarn that I am headed out of town after tomorrow so some responses might take a week to get to.
 
It is the older design. I bought mine right when they started producing units with the upgraded pistons - luck of the draw. On the new design both pistons are beefed up a little. Hopefully my parts on order are the new design. I have no complaints having gotten 11 hrs on the old design. Fortunately, the new design works in place of the old. I was pleasantly surprized at just how easy the YH is to disassemble. REALLY easy. It is a simple design. I saw no signs of wear and the little bit of build up on the reed valves cleaned right off. Even the gaskets remained intact when I pulled the cylinders off. If I had to rebuild this Yong Heng once a year it would still be worth it.
 
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at 11hrs the hard plastic rings on that high piston should have started to wear a bit and become noticeably less efficient.

i bought a complete new piston and was going to swap it out but I attempted to change the rings only

a real pain to get them on, but they fit real tight and it builds pressure much faster than when new

at expense of a little higher temps but worth the shorter times.
 
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Slower fill times are what indicated that my YH had an issue. Even with that buggered up high pressure piston top it was still building pressure but slow and struggled past 3500 psi on the last run. After cleaning everything up, I was once again surprised to find that there was no scoring of the cylinder walls from the broken piece. Worst part is going to be waiting for parts. I've got 270 bar in my 6.8L tank and a 4500 psi fill in my 90cuin tank so hopefully I can wait it out. Wish there was a US distributor for parts.
 
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Yup, the day has finally come. My Yong Heng needs a new high pressure piston top. The screw on piece that holds the top two piston rings gave in. Knew it was going to happen eventually - lasted for 11hrs of run time. The failed part:

1593723805_14298557145efe4b9da15294.85164967.jpg


I just grabbed it with a pair of pliers to unscrew it so it is more chewed up than it was. I ordered enough parts to rebuild it twice (lower+upper piston w/ rod, gasket set, o-ring + seal set and the offending piece). Totaled $65 with tax and free shipping.

Now to the point of my post. I figured that I would offer to take any pictures, measurements or answer any questions that I can while I have it apart. I do have to forewarn that I am headed out of town after tomorrow so some responses might take a week to get to.
Click to expand...

Do you have a link to the source you ordered from? My YH is a backup now but a rebuild "kit" might be worth ordering.
 
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I attempted to change the rings only. a real pain to get them on ...
Click to expand...

Not that difficult if you know the way. The Yong Heng people taught me this method. Only a metal rod is needed : 

https://www.youtube.com/watch?v=jBh9pv-Ub90&feature=youtu.be



How the workers did it in the Yong Heng factory : 

https://www.youtube.com/watch?v=wgg8YouWZfs&feature=youtu.be


 
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I was thinking a piece of rubber pad and a small hose clamp to grip it. With high temp thread locker maybe finger tight is ok?
Click to expand...

I use the collet chuck of my lathe but I believe a drill chuck should work as well.
Click to expand...

What method did you use to remove the worn rings? Did you use a pick or just cut them off with a blade?
 
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Funny, I just finished putting mine back together. Same problem, upper portion of the piston disintegrated. The piston top came with seals installed, so I didn't have to go through that.

Now, it's back together, but won't make any pressure. Any thoughts? Wondering if that little flapper valve thingy on the to of the piston has to be in a specific position and I got it wrong.

Thoughts?



Answered my own question with this video. Went from about 20 PSI to full 300 bar after doing this:



https://www.youtube.com/watch?v=24sGXYkd4NY


 
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