Yong Heng Leak?

The purge valve vents from the bottom of the high pressure block below the knob.

The burst disc vents from a tiny hole in the side of the fitting on one of the flats.

The gauge takes an 11mm wrench on the underside to tighten it. Just tighten it snug.

If you shut the unit down, without purging, after it runs for a short while you may have better luck finding your leak.

Sometimes it takes a bit of detective werq to find a leak. Good luck.

From the sounds/hiss in your video, you've got a very large leak... or open/broken fitting/pipe/hose connection, pressure relief valve BD..?

If you just run/cup your fingers around possible leak sites the difference in the sound of leaking hiss will change with fingers touching anywhere around the leak, and substantially. If you can't pinpoint leak like that, put a few drops of dish detergent in a cup about 1/4 full of warm water and froth it up with your finger tips then spread the froth on suspected leaking areas.

With a massive hiss like you've got, massive soap bubbles will appear instantly when you pinpoint your leak...

Check the bonded seal (dowty seal) washer under the tubing nut at the very top of the HP cylinder. That's where mine leaked but there were extras in the replacement parts that came with my YH. Took 3 minutes to fix.

Gerry52, where did you get the cooling fins that you have on the high pressure output line?

From what you've described, I would look to the gauge, but not just the fitting. Check the gauge body itself. Not always easy to do but I have had a gauge fail internally and leak (mine blew the rubber plug across the room). Others have also reported internal failure of the gauge.

The bonded seal leaked on mine until today. didn't have the proper seal, so threw in a fairly tight o-ring. Stopped the problem for now. Anyone know what size that dowdy seal is? I'd like to replace with the right part.

Oh and the gauges on YH's are garbage. About to install my third gauge today. First two failed, first just quit working, always showed 1000 PSI, second is oil filled and so dark you can't read it. It works, but ya need to be able to read it. Hopefully #3 will be the charm.

Thanks,

I believe if I had another gauge failure (I've had 1), I would just plug it and rely on my gun or tank gauge. This might not be an option for everyone but if it is (and I'm hard pressed to think of a case where it wouldn't be other than using and wanting to retain adjustable shut off) you could eliminate that "problem prone" gauge altogether.

On my second gauge now and it is really nothing better than a hole plug. If (big IF) I replace this one I am going to put the gauge on the end of a fill line and mount it where the YH will not vibrate it to death.

The "cooling fins" are T-05 transistor heat sinks. They were on a Tuxing compressor that was given to me but could never get running. I kept the sinks & put em on my YH. Looked EVERYWHERE for them but can't find em. Think they originally came from Alibaba. 

@siulam, YES, that's where mine leaked. Once I replaced the bonded seal washer I've had zero problems. Undo BOTH nuts on the ends of HP tubing & remove so as not to deform it by only doing the top one.

The bonded seal leaked on mine until today. didn't have the proper seal, so threw in a fairly tight o-ring. Stopped the problem for now. Anyone know what size that dowdy seal is? I'd like to replace with the right part.

Oh and the gauges on YH's are garbage. About to install my third gauge today. First two failed, first just quit working, always showed 1000 PSI, second is oil filled and so dark you can't read it. It works, but ya need to be able to read it. Hopefully #3 will be the charm.

Thanks,

Click to expand...

The size is M12. There should be two of that size in your spares kit. If you would like a cheap supply of relative sizes, He's a link.https://www.aliexpress.com/item/32877796429.html?spm=a2g0s.9042311.0.0.24c74c4dK4Jczf I very much doubt that this will be the source of the leak that the OP is seeking. His machine is brand new. This seal does not usually need replacing until several hours of use.

Mine started leaking at that seal with less than an hour's run time. The seal itself was defective. Surprised me at the time but works perfectly since then.

The second stage output dowty seal is one of the hottest places on the whole compressor. So they are bound to fail sooner or later. Mine failed a couple of times. The Chinese dowty seals are not to be trusted so I bought a cheap kit similar to the one Eaglebeak shows so I would have what I need on hand.

After checking all the connections etc. if you find all is well, try closing the black knobs a little tighter than you have been. I was about to send mine back before I added more pressure on the knobs and that made all good again. The seats are new and may have to be set to stop them from leaking.

If anyone finds a good replacement, let us know. It's an M10, 40mm, 0 to 6000PSI gauge. Should be oil filled as well. If it's not filled, it just shakes apart. I'd like a good quality gauge but don't know enough about the industry to find one. Those on Amazon, ALiexpress, and other places for $15 just don't seem to cut it. I'd spend good money to get one that works.

Edit - Ive been told that the AirVenturi guage works on the Yong Heng, but not positive. If someone can figure it out, that might be an option (Air Venturi at PA)

The Air Venturi gauge does fit but make sure that you get the M10x1 threaded unit. However, I would not recommend that gauge. I have that on my YH as a replacement for the original gauge and it is the same / no better than the original gauge. I am also interested in what better gauges are available.

I would start with this fitting and convert from M10-1 to 1/4" NPT thread so you can use an NPT 1/4" 0-6000 psi glycerin-filled gauge.https://www.threadtoolsupply.com/