Hyundai HY5508 Compressor air leak

[MacBeagle]

Bought this off Amazon as a used/returned/refurbished unit at a knock down price so I sort of knew it was going to have some issues and I wasn't disappointed. Slight air leak. However, it did the various jobs that it was bought for and it's only now that I want to fit a pressure regulator that it needs to be fixed.

It fills up the tank to the required pressure but when the solenoid switches off it very slowly leaks through the plastic end cap in pic A. It seems on closer inspection that the solenoid shaft (C) when release by the deactivated solenoid, doesn't cover the hole, to the tank, in the housing (B). Is there a rubber stopper missing from the end of the shaft or am I barking up the wrong tree?

 

[voipio]

Slow leakage would suggest that the check valve / non-return valve washer or seat has some wear, damage, or contamination. Make sure the receiver is empty, and unscrew the large brass nut shown in image B, and get ready to catch anything that might pop out.

Also check the unloader valve seal at the bottom of the hole in image B and the o-ring in image C (it's possible the o-ring may not have a circular cross section), together with the various surfaces that form the seals. The unloader valve is normally "open" when the compressor is off, so it's the non-return valve that needs to be looked at for the air leakage.

 

[MacBeagle]

Thank you very much for your advice. I will investigate and report back.

 

[MacBeagle]

Removed the brass nut as suggested and got ready to catch flying objects. Damp squib, which suggested weak spring attached to the neoprene stopper. Elongated said spring, and hey presto, no leaks.

Thank you again, Voipio.

I have been a member of this forum for many years, formerly under the name elebub (I changed my email + handle when I retired) and it never ceases to amaze me the depth of knowledge on this forum.

 

[voipio]

There are various causes of leak back. Sometimes there's a bit of swarf, or gunk stuck on the non-return valve seat or in the sealing washer, or a groove forms in the sealing washer, which doesn't always sit snugly in the same place over the valve seat, leading to leakage. The non-return valve springs aren't usually too lively, but the non-return valve pastel (the bit that sits on the spring) can become detached and both can roll out, usually underneath something, hence the need to try and catch them, plus any gunk that comes out with them for the forensics. It's possible to nip other things in the bud, like failing diaphragms, or bits of valve.

 

[tony359]

Hi all
I just registered to say thank you!

I had a massive leak through that valve, the solenoid seemed to be working though. I contacte Hyundai and sent them a video and said I needed a new solenoid valve - it's just the solenoid, not that brass-coloured one.
I wasn't convinced so I googled and found this.

I disassembled the brass thing, found some gunk stuck under the stopper. I cleaned it and it works now. So disappointing that not even the manufacturer can properly diagnose such a simple fault.
You saved me some hassle here, thank you!