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yong heng blew up.

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I do not have a Yong Heng - (currently doing my research for a compressor). Would be nice for the guys that do have them to know what serial numbers have the upgraded piston.
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You might want to check this one ... done all the research .. have a YH and I got that one a week ago ... WAY BETTER! (Quieter, faster, digital, temp stay low), but tested for 1 week only. (But so far is a keeper)

https://www.aliexpress.com/item/-/32911157775.html?spm=a2g0s.8937460.0.0.76bf2e0e79YLVz

and for me cheaper, I pay for the set pressure YH with shipping 450 + taxes! (200 more!) with this, shipping was real real fast (10 consecutive days) and total was about 390 (bit less) and no taxes (got lucky)
 
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Hey guys,

I really did not want to start a debate about aliexpress, so I think I just need to order a new piston and the general consensus is the royal purple is not the problem.

Thank you,

Jim
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I didn't see it as a debate, we're just sharing info and opinions. Each person takes what they can use from it and all is well. 👍

I sent an email to Yong Heng requesting purchase of a piston assembly with paypal. I'm sure they will do it and charge me a small fee.
 
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I might as well pop in with an Yong Heng update..

I got mine and fired it up the first time back in late December.
It was filled with Royal Purple [Cheap from the local NAPA] and run.. run a LOT. 
I completely filled my 90 cf tank from zilch to 4,700psi, and I've been topping it off ever since.. 
In between, I'll also periodically use it to top of guns - just to give it a bit of random run time... 

I think I replaced the oem inline air filter 2 or 3 times, but that's been it. Until' last night.. 

Since it's been chugging along so well, I figured I'd be nice and do it's first oil change..
While draining the RP, I kept the comp angled at about 45* then 90* then 45* angles.. 
That allowed for almost all of the oil to drip out. I also inspected the oil really well.. 
I used paper filters, and while I did notice a tiny bit of metallic sheen, it wasn't very much.. 
I'm talking microscopic looking particles - for lack of better words.. 

I thought that the oil should have been darker, but nope.. It appeared much darker through the window.. 
While some was a bit darker, when in the fingers, most was still very clear, so that was cool..

I topped it back off [oil fill # 2 now] and ran it for about 15 min - to top of my 90 cf tank again. 

While it's a bit annoyingly loud - running in my kitchen - it still worked flawlessly. *Knocking On Wood* 

It's nice to see that you guys are finding better internals for these things! [rebuilding is inevitable]
While it's nice to know we could rebuild them before, going with improved parts is way better!

Great finds and thanks for the shares!

🙂👍 

Sam -
 
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I'll note that I always remove the cover to change the oil and wipe everything out on my YH. The shape of the gasket on mine would trap a small volume of oil near the sight gauge. That oil will be darker and will build up more debris due to not flowing but just getting splashed in. I removed the thin "flap" from that section of gasket to allow better flow and stop the trapping of oil there. Probably doesn't make a big difference but does allow the actual color of the oil to be seen.
 
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I removed the thin "flap" from that section of gasket to allow better flow and stop the trapping of oil there.
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That flap is to prevent stirred-up oil droplets from getting to the breather tube. If it is removed, I believe a lot more oil mist will be sprayed out from the breather tube during operation. This is not good for health if the compressor is used indoor.
 
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I frequently see people trying to keep their YH from exceeding 50*C during operation. The manual that came with mine about 3 months back says not to exceed 75*C and that 50 to 70*C was the ideal operating temperature. I have not filled any tanks yet but in filling a gun and the filtration system it quickly reaches about 55* and stabilizes there. This is running for about 3 to 4 minutes up to 200 bar. This causes no noticeable temp rise in my coolant of about 1.5 gallons of 50/50 Dexcool.

I know this is not working the machine very hard but I'm wondering where the 50*C goal came from. General concensus? Of the several pictures I've seen of cracked piston domes none showed evidence of overheating. And for that matter the aircooled first stage gets considerably hotter than 50*C.
 
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I removed the thin "flap" from that section of gasket to allow better flow and stop the trapping of oil there.
Click to expand...

That flap is to prevent stirred-up oil droplets from getting to the breather tube. If it is removed, I believe a lot more oil mist will be sprayed out from the breather tube during operation. This is not good for health if the compressor is used indoor.
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Possible but I don't believe so.
 
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I frequently see people trying to keep their YH from exceeding 50*C during operation. The manual that came with mine about 3 months back says not to exceed 75*C and that 50 to 70*C was the ideal operating temperature. I have not filled any tanks yet but in filling a gun and the filtration system it quickly reaches about 55* and stabilizes there. This is running for about 3 to 4 minutes up to 200 bar. This causes no noticeable temp rise in my coolant of about 1.5 gallons of 50/50 Dexcool.

I know this is not working the machine very hard but I'm wondering where the 50*C goal came from. General concensus? Of the several pictures I've seen of cracked piston domes none showed evidence of overheating. And for that matter the aircooled first stage gets considerably hotter than 50*C.
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Mine would hit 70c when new but now it stays about 50c with no ice.
 
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Queequeg,

My book says that the coolant temp should be between 50 and 70c and that the max working temp should not go over 75c, if it does go over it says to replace coolant. Can anybody tell me what the oil level should be? at first I thought it just had to be over the red circle now I see that if it is to high it will cause carbon issues which might be the cause of the piston breakage from carbon deposits on top of the second stage.

Thank you,

Jim
 
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... what the oil level should be? at first I thought it just had to be over the red circle now I see that if it is to high it will cause carbon issues ....
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Filling to the red dot is OK. I believe if the oil level is too high, the connecting rod or the balance weight of the crank shaft will hit the oil resulting in more vibration and additional loading on the motor. This is not a combustion engine so I doubt if there can be any carbon deposit on top of the piston. I recently took my YH apart and could only see some dirt which is probably a mix of oil and metal powder. The dirt can be easily wiped away by fingers.
 
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PS, There is also a 3 ring second stage piston rod and a 4 ring second stage piston rod version on AliExpress. Anyone know if either will work as long as the lower connecting rod is the right size?
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The three-ring pistons are a slightly different size and are not interchangeable. If your pump has Yong Heng printed on the side of it, order only the three-ring type that the add states is for that brand. The four ring piston in the link that you posted is only suitable for a Tuxing branded and perhaps a few rebranded units. If your pump is one of the generic brands, you will need to take it apart to be sure of what type it is before trying to find a replacement. They may all look basically the same but there are some subtle differences in the spare parts.
 
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Well for a start the top of your first stage piston head is clearly cracked. Hard to say what else is wrong from the pictures alone, but that could be it. 



My personal experience with the YH compressors is that they're essentially disposable. Like anything vastly less expensive than competing products, they have their advocates and that is fair, but how many times are you willing to have the thing fail, tear it down, source parts, and rebuild it? Only you can answer that question, but that really should determine whether you buy a whole new one, repair it, or source a better compressor. *shrug* The royal purple full synthetic compressor oil is most certainly not the cause of your problem though and should be fine.
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Lets do some math here. Quick glance at Amazon shows the HY runs around $300 give or take. Now if we assume a "better compressor" is going to set you back $1000, on the low side, you are buying 3 HY and having $100 left over. I know some of the "better compressors" are not field serviceable, so you are holding on to that big box, and dealing with shipping that heavy thing in for what many that own the "disposable" HY units as routine service.

Plus in looking over several threads on this very board it seems that the "better compressors" need service at about the same hour run times as this "disposable" machine.

You are correct, only you can make the decision if you are the kind of person that can handle popping out a whopping $4 for a new piston and the install of that....or are you better served by sticking it in a box mail it off, wait for others to service your machine, then mail it back to you....all on your dime.


 
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Well for a start the top of your first stage piston head is clearly cracked. Hard to say what else is wrong from the pictures alone, but that could be it. 



My personal experience with the YH compressors is that they're essentially disposable. Like anything vastly less expensive than competing products, they have their advocates and that is fair, but how many times are you willing to have the thing fail, tear it down, source parts, and rebuild it? Only you can answer that question, but that really should determine whether you buy a whole new one, repair it, or source a better compressor. *shrug* The royal purple full synthetic compressor oil is most certainly not the cause of your problem though and should be fine.
Click to expand...

Lets do some math here. Quick glance at Amazon shows the HY runs around $300 give or take. Now if we assume a "better compressor" is going to set you back $1000, on the low side, you are buying 3 HY and having $100 left over. I know some of the "better compressors" are not field serviceable, so you are holding on to that big box, and dealing with shipping that heavy thing in for what many that own the "disposable" HY units as routine service.

Plus in looking over several threads on this very board it seems that the "better compressors" need service at about the same hour run times as this "disposable" machine.

You are correct, only you can make the decision if you are the kind of person that can handle popping out a whopping $4 for a new piston and the install of that....or are you better served by sticking it in a box mail it off, wait for others to service your machine, then mail it back to you....all on your dime.

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The mid priced "better" units have the same chinese compressor units with a few added bells and whistles like coiled tubing to act as a heat sink and/or drier tubes. Which explains the similar longevity you mention. Most of them have metal enclosures so you can't see the components until you dig deeper.
 
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