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Air Compressor dying / midget with a ball peen hammer

jrlp

Well-known member
Joined
Mar 20, 2012
Messages
459
Location
Laredo, Texas
I bought one of those small 20-25 gallon upright Husky oiled compressors around 5-6 years ago. The kind you can run off 110/220v, and has a pretty nice cast iron oiled compressor on it. When I first got it, I went through, upgraded all the piping to larger size, nice regulator to ditch the tiny 1/8" input on a 1/4" npt regulator, and messed with the electrics.

Stock it would kick on at around 85-90psi and cut off at ~120. It now kicks on at 120 and off at ~165. Been that way since I broke it in around ~20 hours on it's first oil change.

Anyhow, this thing has been run hard. I always kept up with oil changes on it, full synthetic, changed air filters religiously. It actually ran a medium sized haunted house and my plasma non-stop for 2 months. I don't think it ever stopped running for more than 10 minutes, except for around 8 hours at night. It was piped in and actually filled 2 other 30 gallon tanks. It has hundreds of hours and never given me a single problem, until recently.

When it's filling, regardless of the tank pressure, I get this non-rhythmic tapping sound that you can easily hear over the compressor at 20-30 feet. It sounds like someone tapping steel with a ball peen softly. I've been through it, tightened every bolt, nut, pipe fitting, hose, wire, and belt.

What makes it weird is that it isn't constant. It will happen every 3 to 10 seconds, regardless of tank pressure. Is the pump dying?

I have a HUGE HUGE job coming up, and am going to run this this thing hard. I have over 3,000 linear feet to plasma bevel on 3/8" alone. Probably ~400 plasma cuts in 3"x3"x3/8" angle as well. This is an on-site job, well actually 2 separate ones that are related, but the first one is 40 miles out of town in the boonies.

I don't want to have to, but I may have to pick up a gas powered compressor. I have enough kW on my set (11kW bobcat) to run the electric compressor and my plasma full tilt(probably around 7kW @ the arc voltage required for 3/8"), but just barely any overhead if a helper is gonna run a big grinder or I'm running big lights.

Sigh.
 
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zkling

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Joined
Jan 23, 2007
Messages
16,939
Easy, just take the hammer away from the midget. :bounce: Any airplane guys here? :dunno:

When you said you went through the unit, "Tightened every nut and bolt" did you take the pump apart? Check the connecting rod to crank journal fit?

Could possibly your check valve hammering. Can you pinpoint where the noise is coming from? Try running the motor by itself with the belt off, any change in noise?
 
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J

jrlp

Well-known member
Joined
Mar 20, 2012
Messages
459
Location
Laredo, Texas
Easy, just take the hammer away from the midget. :bounce: Any airplane guys here? :dunno:

When you said you went through the unit, "Tightened every nut and bolt" did you take the pump apart? Check the connecting rod to crank journal fit?

Could possibly your check valve hammering. Can you pinpoint where the noise is coming from? Try running the motor by itself with the belt off, any change in noise?

No, I didn't take the pump apart. I didn't take the belt off, truthfully, but spun them both by hand looking for runout or the noise and found none. I'll order a new checkvalve today. Or rig up something to work in the mean time.

My money is on the check valve (in tank)
Compressor-In-Tank-Check-Valve-6X213_AS01.JPG

http://www.grainger.com/Grainger/CDI-CONTROL-DEVICES-Compressor-In-Tank-Check-6X213?Pid=search

I had the same problem, no other problems,like leak-back or anything, it just started making noise. And it was hard to locate (noise).

Hell I thought it was a rod or something :thumbup:

I was thinking rod noise also. I'm hoping it's the check valve! Thanks guys! I really didn't want to have to drop $1k+ on a new compressor just for this job. As it stands, I may have to drop double that on a new wire feeder for this job, and that eats up the profit margin real fast.
 

PowerDubs

Well-known member
Joined
Jan 20, 2009
Messages
406
If it is a HUGE HUGE job worthy enough of worry..then buy a new compressor....sheesh. How much can a new "those small 20-25 gallon upright Husky" cost anyway?
 
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jrlp

Well-known member
Joined
Mar 20, 2012
Messages
459
Location
Laredo, Texas
Oh, I wasn't going to bother with another small upright. They're $400 or so.

If I buy a new one, the amount of time I spend doing mobile now days, I'd just get a good gas powered one. That jumps up to ~$1600 or more.

I have on board air on my work truck, but only 6cfm @ 100psi.
 

Trash Mech

Well-known member
Joined
Jan 27, 2013
Messages
86
Oh, I wasn't going to bother with another small upright. They're $400 or so.

If I buy a new one, the amount of time I spend doing mobile now days, I'd just get a good gas powered one. That jumps up to ~$1600 or more.

I have on board air on my work truck, but only 6cfm @ 100psi.

Miller Big 40 with an air pack. I know it bumps it up to 16000 or more but dang what a set up. All kidding aside it does sound like the check valve, but I'd say you definitely got your money's worth out of that thing.
 

Outlawmws

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Joined
Aug 9, 2011
Messages
39,274
Location
The Badlands
Use a mechanics stethoscope with one of these probe rods to find the knock. I'm also thinking con rod right off the bat, but there are any number of possibilities, including the main valves, and that check valve
 
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