Air Compressor Oil Bubbles When Running

Lanse · Apr 3, 2017

Hello everyone!

So, I've got a ~1 year old Quincy compressor (total junk, BTW), that's never been overworked and has always been run with synthetic compressor oil in it.

Lately, I've noticed three things about it:
1) The hoses running from it get HOT, as in almost too hot to hold only 1-2 feet away from the tank
2) It takes FOREVER to build pressure, it now runs continuously doing jobs which it used to run intermittently on
3) The oil "bubbles" and "gurgles" when you look at it through the sight glass... It used to only vibrate a little, but now theres clearly air bubbles flying around and popping in there.

Is this normal? I was painting with it when I noticed these things, it used to run my HVLP gun just fine (60 gallon tank) but now runs constantly to feed it. Did I just overheat it somehow, or something? What should I be looking for? I know nothing about air compressor pumps but I suspect something isnt right here. Am I simply clueless? Or what?

Quincy only gives their compressors a 1 year warranty now, which I'm completely under-whelmed by. If this thing needs a new pump, can anyone recommend one?

kcm.MN · Apr 3, 2017

Check your air intake filter. Sounds like it's plugged up.

Ken Macfarlane · Apr 3, 2017

Running much hotter that usual - likely leaking valve or piece of dirt/paint stuck in one but if getting lots of bubbles in the oil maybe rings.

If it's leaking that much into the case the vent would be noticeably venting tons of air.

Steve@Advance · Apr 3, 2017

Is this a 2 stage pump? (One cylinder bigger than the other)

If so, sounds like the high pressure (small cylinder) valves have failed.

When that happens, the low pressure side tries to do all the work, makes it overheat, lower the volume, over amp the motor.

Could also be carbon, but doubtful with synthetic oil and only a year old.

Also, if it has pneumatic unloaders, (a diaphragm on top of the cylinder head with a 1/4" line to it) be sure they are retracting when up and running.

Geo-TH,In · Apr 3, 2017

Lance,
If you lived in Terre Haute, I would make you a deal on an old 5 hp twin stage air compressor I used to use in my hobby paint shop. It ran all day long for years. I even rigged up a way to condense moisture out of Humid Indiana's air and then had an old toilet paper air filter for paint gun. Zero moisture came out the gun. Gallons of moisture came out the condenser.
geo

Russ from MN · Apr 3, 2017

Broken valve.

DLMKA · Apr 3, 2017

What model? When I worked there last they were just starting to dip in to the cheap Italian and Chinese compressor re-branding game. I wasn't impressed with them but for most home shop compressor users they would service just fine.

If it's getting hot you likely have a bad valve or the check valve going into tank is stuck shut. Any chance you have a clamp on amp probe? Can put that on one leg and see how much power it's pulling. Could also be a blow by issue but you'd see oil mist from breather. Check the drain valve in the bottom of the tank, if there is oil being carried over to tank it has ring(s) upside down.

Betting $10 it's a discharge valve reed that's chipped or carboned up.

Air Compressor Oil Bubbles When Running

Lanse

Well-known Member

kcm.MN

Well-known Member

Ken Macfarlane

Well-known Member

Steve@Advance

Well-known Member

Geo-TH,In

Well-known Member

Russ from MN

Well-known Member

DLMKA

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