Buying a used air compressor

zingo

I have the opportunity to buy a used, Craftsman air compressor and will be looking at it tomorrow. The owner is checking on the build date, but says it runs fine; I just sold my dinky portable air compressor to buy one that can flow enough for air tools. It's stamped as a 240v 5hp, 15gal belt driven oiled twin piston design with 30A twistlock plug

I know Craftsman is a good brand and parts can be more available than other brands if you break something, but anyone have suggestions on buying used?

lightman1

Just check to see if the motor starts fast without hesitation. Check the pressure switch and regulators. Slow motor start is a sign the brushes are going bad or was not fed a steady supply of juice. Wire in a 30A twistlock receptacle as close to the main panel as possible with at least 10 guage wire.
Check the nameplate on the motor for breaker sizing. Calculate breaker at 125% of load for hard start amperage surge.
No squeking/grinding noises from to cylinders is a plus. Check oil level.

DaveHo

15 gal is pretty small. What is the rated CFM & at what pressure? What air tools are you wanting to run?

tonyb

Why not just buy a new one, they aren't that expensive. Just to run air guns off of it, nail hammers maybe ? Blow up that heavy Scottish skirt ?

motorhead43026

Buying a used air compressor is like buying a used condom. Unless you know the history of it I would pass.

Plus its a Crapsman.

lightman1

motorhead43026 wrote: »

Buying a used air compressor is like buying a used condom. Unless you know the history of it I would pass.

Plus its a Crapsman.

Hey!Hey! Whoa! No brand bashing now.

zingo

I don't normally need tons of air, or have tons of space in my garage, but I mostly wanted a motor that could keep up with supply when used for a Saturday project. It's rated at max 125psi, 11.3 CFM at 40psi and 9.3cfm at 90psi.

zingo

I have an impact gun, a rotary tool, a ratchet, and hammer/chisel. Going to pick up a finish nailer, but I know that doesn't require much.

dkg999

You need to check which OEM made it for Craftsman. Not all Craftsman tools have replacement parts available. IIRC toolparts.com has the OEM information and parts status for Craftsman tools.

gdb

The compressor is fine....it's the tank's age/drain history that's of concern, IMO. New is a good thing. Quincy (USA) is the best thing. If you do snag the used one, I recommend shielding it with bunches of used tires, etc. to act as a blast mat. https://www.google.com/search?q=compressor+tank+explosion&biw=1103&bih=555&source=lnms&tbm=isch&sa=X&sqi=2&ved=0ahUKEwiZ6q-suKjLAhUEND4KHbNVCXIQ_AUICCgD

https://youtu.be/KVP_A7eGYxw

gudnoyez

http://rolaircompressorpumps.com/pumps.shtml?gclid=CIX-vea9qMsCFVc1aQodBl0L9g

Look for a used Rolair best compressors made finding a used one is rare most people don't want to give them up. I suggest you ask the person selling you what ever compressor you decide to get if he had drained the tank after each use.

littlewoodboats

9.3 cfm @ 90 psi with a 15 gallon tank will not be enough for high volume tools like sanders and air files. A used compressor should not be a problem as long as it has been maintained. If the oil looks like it has never been changed then it probably has not been. Before I would buy it I would want to drain the oil through a paint filter to see what if anything might come out. Same thing for the tank. Moisture in the tank is normal. If it blows out looking like watered down Chocolate milk then there is reason for concern and I would walk away.

Give careful thought to the tools you might use to guage the capacity you will need. I go by my highest volume tool (a 3' blocking sander) and try to give myself at least a 25% buffer if at all possible. I would not be afraid of a used compressor but would check it carefully.

[Deleted User]

Why waste time. I am the inventor of the hoseless air compressor. Yep. Prototype in hand. Haha. Tank at my neighbors, tool in my hand.

mrbiron

If I were to ever buy a use comp, which I wouldnt, I'd ask the owner to start it an hour before I got there. Then, when going over the machine, I'd tighten the bleeder screw on the bottom of the tank. If it runs mud, stay away. If it's clear, the man takes care of his equipment.

txcoastal1

dkg999 wrote: »

You need to check which OEM made it for Craftsman. Not all Craftsman tools have replacement parts available. IIRC toolparts.com has the OEM information and parts status for Craftsman tools.

This....year by year Craftsman changes OEM manufacturers

zingo

Thanks! I'm going to check out the unit today and see if it looks reasonable.

zingo

Bought the air compressor for $60! Owner had replaced this unit with a hard plumbed and hard wired shop compressor. He claims to have regularly changed the oil, although it does leak a little, and regularly empty the tank of clear but slightly oily water. The air filter does need to be cleaned, but the unit does have an air separator installed and everything seems to be in good condition; even plastic covers are intact. Now I just need to install the 240v 30A outlet under my electrical panel and I'll be up and running!

zingo

Outlet was installed two weeks ago and the air compressor runs like a champ after a new air filter, a new hose fitting, and tightening a few connections. I'm fairly impressed with this unit built in the early 90's; DeVilbiss 2 cylinder oiled compressor with GE electric motor. The belt still looks good, but the unit is noiser than I would have expected; just a little quieter than my previous oilless compressor. I'm planning on changing the oil this week, but I'll keep tweaking it to see if I can get it down a few dB.

I ran the compressor yesterday to 120psi, then ran a rotary tool at full bore. The air pressure dropped to 110psi after 10 seconds, but then the compressor kicked on and held the pressure at 110psi as long as I ran the tool wide open. Knowing that I didn't want an enormous tank, my goal was to get an air compressor that can keep up with air tools, and mission accomplished!

zingo

sucks2beme

Next time I buy one, it's going to be a vertical tank.
Also, getting a long hose on a reel is a must. My current reel
and hose reaches to the end of the driveway. So the compressor doesn't
have to move anywhere.

gmcman

I have that compressor's big brother in a 30 gal tank. After using the 110V models which can't keep up with hungry air tools, this one bridges the gap nicely before a large vertical unit.

For $60 you stole it if the tank has been drained regularly and in good shape. You could easily add another 15-20 gal tank inline and place it out of the way and would save some run time on that motor.

Nice score.

zingo

The tank drains clear, although a little oily, which I think is okay as the oil level in the compressor is fine. I will get a longer hose when I do our cabin roof this summer, but I just didn't have room for an upright unit at this time in the garage. I'm glad I found this unit used, and can't believe I was even considering a 120v compressor for tools!

zingo

I was thumbing through the manual yesterday trying to figure out how to regulate the pressure on this compressor. Once full, the motor kicks on when the pressure drops to around 105psi and then will kick off again at 125psi, but I would like to run some tools lower. I couldn't see how to adjust the pressure, and I know some models aren't adjustable (my old double stack 2gal had separate tank and line pressures), so maybe I need to add a second regulator to accomplish that?

Thanks for any thoughts!

DaveHo

The pressure switch controls when the compressor runs & shuts off. If there is only one gauge it's just showing tank pressure & likely has no regulator. You'll need to add one.

exalted512

Yup. Just an external regulator. I'd add an air shut off immediately coming out of the tank that way you can just turn the valve off and not worry about slow leaks from the hose and/or tools hooked to it, followed by a dryer of sorts to keep moisture out of your tools.
-Cody