Used Compressor Shopping - Advise On What To Look For

[TheLoamRanger]

Hey All,

Background: I've been looking for quite some time for a new-to-me compressor. Based on my air needs, a single phase 5 HP two stage is what I'm looking for but I would also consider a 7.5 HP if the price was right.

My two main goals are low noise and built to last. I was originally planning on getting an Eaton quiet piston compressor with the intake muffler, but that gets pretty expensive with shipping and tax ($3k+ pretty easily, with $1k being tax and shipping alone). I can make my own intake, route intake outside, build and enclosure, etc, but quieter overall is better (baby on the way!!! and this will go right underneath the nursery in the garage). I also need to buy/build an air dryer setup - cooler discharge air is a major bonus.

I have started paying more attention to the used market recently, but I am a little hesitant on some older units. Best I've found so far is a Champion HR5-8, made in the late 80's that has been stored for the last decade. The asking price is almost $1200. These look like fantastic units - disk valves, unloaders, serviceable, USA made, etc so I'm super interested. Looks decent in the pictures.


What do you guys typically look for when buying a used compressor?
What about if it isn't under power for a test run?


Thanks Team,
-Derek

 

[BlakeTheCarGuy]

The ones from the 80s are very powerful and amazing. We had a couple from the 80s when I was in high school they seem so much more powerful but also a lot louder. I can’t think of any quiet compressors that I have found. What to look for when buying used is damage of course and make sure everything is functional and make sure that the compressor is one you want and will fit where you need it. At home I have a 20 gallon Craftsman my dad bought it new in 1997 it’s not loud but it’s also not quiet. At work we have some very big industrial ones which are quite loud.


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[Don1357]

Don't be fooled by "peak" horse power, the inflated number that is much bigger than what everybody understands as horsepower. I have a oldish Campbell Hausfeld that has in big fat letters "7HP". They don't even bother to tell you that this is "peak" horsepower, your first clue is looking at the plate on the motor and seeing SPL where the horsepower rating would be. It stands for "special" which in turn stands for "this vendor is lying about horsepower and if we want to provide them with motors we can't tell you the real power of this unit, thus we call it special..."

My motor is probably 5hp if I'm lucky, 17.3amps at 240v

 

[Jswain]

If it isn't under power for a test run you are certainly taking a gamble. Research what a rebuild kit would cost(rings/valves/gaskets etc.) And factor that into the price as well as assume you may have to install one.

I bought my last unit without seeing it run and it paid off for me as everything he said about it was true and it runs great so it's not all bad...

Make sure you can spin both the pulleys by hand, make sure the tank drain is open and an absurd amount of water hasn't been sitting in the tank for all that time. Any name brand unit of that era will be an excellent unit champion being at top or very near of the pack. Make sure there is no damage to the tank itself, no welding on it where there shouldn't be etc.

 

[TheLoamRanger]

@Blake: I guess quiet is relative. I'm just looking to keep it quiet as far as piston compressors go. Oil lube with low rpm pump & motor. I can always implement additional mitigations from there as necessary. Air is important enough to me that I'll make room if it's a good unit! Old iron from the 80's sounds appealing if in good shape.

@Don: Good point - I'll be on the look out for inflated numbers. Continuous 5 HP rating is what I'm looking for, not peak rating. Current draw indicated on the motor should indicate, like you mentioned.

@Jswain: All are good considerations for inspection. Thanks for passing it along. I'll add each item listed to a checklist. Gaskets appear to be cheap, but replacing valves/rings/larger items start to add up quickly.

 

[The Tool Tyrant]

I'll add...although not usually a deal breaker (especially on used units) Is receiver size and orientation (vertical vs. horizontal). More storage = Less cycling = motor longevity.
I prefer a vertical receiver for two reasons, first, they take up less space and second, they channel / drain condensation more effectively than a horizontal.

 

[Citation]

Compressors without magnetic starters are almost always "light duty". I mean they may be a beast for your need but the higher end units all have magnetic starters vs running the motor right off the pressure switch. If this is something you want to use to paint your cars on weekends it probably doesn't matter. If time is money and you do this every day, get one with a magnetic starter.

As for noise levels, I agree that you can buy/make an intake muffler. I was impressed with just how much it helps to put a rubber hose somewhere along the air intake. In my case it was slipping a rubber hose over the intake snout of the air filter housing. With other filter types I might look at using a 5 gallon bucket, lined with foam rubber and an internal baffle + a rubber hose to the compressor head as a DIY muffler.

This is a similar idea but used a car muffler. Since we don't care about hot gasses I see no reason to use metal.

 

[redmondjp]

Hey Derek,

I'm also in the Seattle area and check CL for compressors every now and then. I would also watch Facebook Marketplace (I'm not on FB at all but know a lot of people who use that instead of CL now) and OfferUp. Good deals disappear quickly, as in the same day.

It sounds like you know what you are looking for, so keep a daily check going and be ready with your truck or trailer and a wad of cash. I just bought a Champion (Grainger brand but made by Champion) 5HP with their RV-15a pump on it and a 3-phase motor for $180 out in Fall City, for my brother's shop. He already had the single-phase motor which is already on it and the unit is up and running.

So if you can get a good enough deal, it may be worth looking at 3-phase units and then sourcing a single-phase motor, if you can handle a bit of mechanical and light electrical work. If it's a 208V starter, it will probably also work on single-phase 240V but you will have to swap out the heater strips to match the motor that you are using.

Oh, and don't forget - one way to search CL is to use the "include nearby areas" check box - you will get more results and perhaps a better deal, but you might have to spend a day going to get it and bring it home. For example, if you are willing to go down to Longview, there is a Quincy 325 with spin-on oil filter, with a 7.5HP 3 phase motor, sitting on a 80-gallon horizontal tank, for $400. The Quincy pump is a Record Of Change (ROC) 103 which I think dates it to the late 1980s-early 1990s period. For about a grand you can have a compressor that you can hand down to your grandchildren, with a bit of elbow grease and sourcing a single-phase 5HP motor.

https://portland.craigslist.org/mlt/hvo/d/longview-80-gallon-air-compressor/7212367235.html

Here's a Big Red Air 80 gallon 2-stage upright with a single-phase Baldor motor on it (at least 5HP, may be 7HP) for $1150 just east of Portland. This is the same company that makes the big SnapOn compressors that retail for close to $4K (you would pay an extra $2K for that name on the side in this case):

https://portland.craigslist.org/mlt/tls/d/portland-big-red-commercial-air/7200417116.html

 

[pcmeiners]

"The ones from the 80s are very powerful and amazing. "

Yep, a bit before compressor quality started down hill.

To me the ultimate compressors are the Quincy QR series , the QR325 and larger units, pressure lubed, parts available, many on Ebay.

Champion HR5-8, is good, splash lubricated, parts are available, not many on Ebay.

 

[The Tool Tyrant]

I must concur with PCM regarding the Quincy QR series.
2nd & 3rd are a close tie between the Champion R series pumps (with disc valves) and Saylor-Beall, although because of the ease of valve servicing on the Champion (no special tools required) I'll give the tied base to them.
Both Champion & Saylor-Beall do offer a pressure lubed option, but I rarely see them offered in the 'used' market.

If you buy used, I'd go ahead with a valve service along with normal maintenance items (oil, air filter, belt tension & alignment) as most folks never service the valves, even though it's a scheduled maintenance item.

Good luck on your search!

 

[Iron Beaver]

I spent many months looking on FB and finally found an old Curtis (not FS-Curtis) Master-line D95 5hp 80 gallon 6 hours away. I made the drive and got it. It's been a beast and was worth every bit of the $1300

I find the most bang for my buck comes from buyng 3-phase equipment and repowering it with single phase motors. That's how I got my wood lathe and now the compressor.

 

[redmondjp]

I must concur with PCM regarding the Quincy QR series.
2nd & 3rd are a close tie between the Champion R series pumps (with disc valves) and Saylor-Beall, although because of the ease of valve servicing on the Champion (no special tools required) I'll give the tied base to them.
Both Champion & Saylor-Beall do offer a pressure lubed option, but I rarely see them offered in the 'used' market.

If you buy used, I'd go ahead with a valve service along with normal maintenance items (oil, air filter, belt tension & alignment) as most folks never service the valves, even though it's a scheduled maintenance item.

Good luck on your search!

There is a Quincy 325 that is a 2-hour drive south of the OP for $400, linked in my post above. Personally I would go grab that one. Pressure-lubed and with the optional spin-on oil filter too.

 

[TheLoamRanger]

Thanks for all of the replies everyone! Sorry for the late reply - got pretty busy. There is a lot of good info here.

I called the seller of that Champion with the R15 pump. He didn't have it under power, but he casually mentioned he'd bring it by on his flat bed for me to wire up in my garage to test. It was in surprisingly good shape, but definitely needs an oil change. After a fiasco with my crappy HF engine hoist not working, we pieced it out to get it off the truck (after running it). I think it will look good in my garage. I will be replacing oil and a few other parts, then I think she'll be spot on for what I need...until I have to set up a dryer (I can see the need coming...).


I was also looking at 3 phase units starting a little while back, but was actually a little surprised about how expensive the single phase motors can be to retrofit. Where do you guys normally source these 5-7.5 HP single phase motors?

Also, a Quincy 325 would be amazing. If I wasn't leaving town for the next couple weekend, I'd seriously consider checking out that one a little south of me. My old man is actually in the market too....hopefully it's still around because those are such a cool design and I would LOVE to get my hands on one.

 

[BlakeTheCarGuy]

Thanks for all of the replies everyone! Sorry for the late reply - got pretty busy. There is a lot of good info here.

I called the seller of that Champion with the R15 pump. He didn't have it under power, but he casually mentioned he'd bring it by on his flat bed for me to wire up in my garage to test. It was in surprisingly good shape, but definitely needs an oil change. After a fiasco with my crappy HF engine hoist not working, we pieced it out to get it off the truck (after running it). I think it will look good in my garage. I will be replacing oil and a few other parts, then I think she'll be spot on for what I need...until I have to set up a dryer (I can see the need coming...).


I was also looking at 3 phase units starting a little while back, but was actually a little surprised about how expensive the single phase motors can be to retrofit. Where do you guys normally source these 5-7.5 HP single phase motors?

Also, a Quincy 325 would be amazing. If I wasn't leaving town for the next couple weekend, I'd seriously consider checking out that one a little south of me. My old man is actually in the market too....hopefully it's still around because those are such a cool design and I would LOVE to get my hands on one.

Wire it up? I’ve only seen the ones that plug into the wall.


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[TheLoamRanger]

Wire it up? I’ve only seen the ones that plug into the wall.


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I just meant that he brought it by for me to test under power. I plugged it into my 50A welding outlet to test (NEMA 6-50 receptacle, 50A circuit.). In my actual install, I was planning on hard wiring it in with a disconnect, rather than using a plug. If there is little value I could be convinced otherwise. I'm honestly not 100% up to speed on what the regulations are for a 5HP motor yet.

 

[BlakeTheCarGuy]

I just meant that he brought it by for me to test under power. I plugged it into my 50A welding outlet to test (NEMA 6-50 receptacle, 50A circuit.). In my actual install, I was planning on hard wiring it in with a disconnect, rather than using a plug. If there is little value I could be convinced otherwise. I'm honestly not 100% up to speed on what the regulations are for a 5HP motor yet.

Oh ok cool I didn’t know you could wire one in. But that’s why I am a car guy and not a compressor guy lol. Mine just uses a regular plug for the wall and it works and doesn’t blow the breaker or nothing and I just unplug it until I need to use it again.


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[matt_i]

Ideally I'd look for one at an estate sale.

Vs. one that was decomissioned from a plant/factory or auto repair shop.

The former: probably likely used sporadically. The latter, probably heavily.

That's not really a quantitative way of looking at it but how I'd attempt to approach the problem.

 

[Iron Beaver]

I was also looking at 3 phase units starting a little while back, but was actually a little surprised about how expensive the single phase motors can be to retrofit. Where do you guys normally source these 5-7.5 HP single phase motors?

Surplus Center and Ebay.

 

[Iron Beaver]

Oh ok cool I didn’t know you could wire one in. But that’s why I am a car guy and not a compressor guy lol. Mine just uses a regular plug for the wall and it works and doesn’t blow the breaker or nothing and I just unplug it until I need to use it again.
l

I chose to hard-wire mine with a safety disconnect. It's on it's own dedicated 30A 220V circuit, and if I put in an outlet the compressor would be plugged into it all the time, so why pay extra for basically a fancy junction box?

 

[BlakeTheCarGuy]

I chose to hard-wire mine with a safety disconnect. It's on it's own dedicated 30A 220V circuit, and if I put in an outlet the compressor would be plugged into it all the time, so why pay extra for basically a fancy junction box?

I honestly didn’t know you could hard wire them in lol. I like the idea on the safety disconnect.


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[TheLoamRanger]

Thanks for the feedback everyone. Picture attached.

I will hardwire it in. It actually came with a disconnect switch that I mistakenly thought was a mag starter in the CL photo, and the seller wasn't knowledgeable on the specifics over the phone. While I did want a mag starter, I'll just run this until I have issues, then upgrade the whole setup as necessary.

I'm going to redo the intake setup, outlet plumbing, pressure switch/tank pressure gauge setup, drain plumbing, and throw it up on vibration isolation leveling feet. It should be a sweet setup once everything gets tidied up a bit!

These bigger compressors are neat pieces of engineering. I've definitely been nerding out a bit as I've been going over it.

-Derek

 

[Citation]

Careful, the terrible you have could be the switch welds itself on. Also, does that motor have internal thermal protection? If not you really want to add a starter. It's about $100 for a lower end model.

 

[TheLoamRanger]

Careful, the terrible you have could be the switch welds itself on. Also, does that motor have internal thermal protection? If not you really want to add a starter. It's about $100 for a lower end model.

@Citation: Thanks for being the voice of reason. I just checked out the motor and pressure switch in more detail. Looks like I'm adding a mag starter now. The pressure switch is only rated for 3HP single phase (5 HP three phase) and no thermal protection on the motor.

 

[pcmeiners]

Yo get the "you ****" award on this. The compressor look slightly used. Yes get a starter, try to get one with an adjustable overload instead of the mechanical bimetal thermal overload. This unit deserves an hour meter also

Truly low end starter....

https://www.ebay.com/itm/5HP-Single...377012?hash=item3acc6690f4:g:QhEAAOSwRTtbMPF0

Better, UL ....

https://www.ebay.com/itm/Unused-Sur...986122?hash=item421bc8cd4a:g:tTgAAOSwgENe~Ozg

 

[csp]

I honestly didn’t know you could hard wire them in lol. I like the idea on the safety disconnect.

Once they get over about the 5hp mark with single phase, they have to be hard wired in.

This is true running HP, not the advertised peak HP ratings you see on cheaper compressors.

 

[BlakeTheCarGuy]

Once they get over about the 5hp mark with single phase, they have to be hard wired in.



This is true running HP, not the advertised peak HP ratings you see on cheaper compressors.

Thanks for the info. Mine at home is just a 2HP Craftsman that my dad bought in 1997 so it has no problems running just being plugged in. I think ours at the shop may be wired in but I’m not too sure.


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[wafrederick]

If they have an aluminum block,run.The air compressers with the cast iron motors are a lot better

 

[Citation]

@Citation: Thanks for being the voice of reason. I just checked out the motor and pressure switch in more detail. Looks like I'm adding a mag starter now. The pressure switch is only rated for 3HP single phase (5 HP three phase) and no thermal protection on the motor.

Glad you noticed that. It looks a bit like a franken-compressor setup but made with good parts. As installed that air intake will probably be a bit loud but I bet you could improve things with a DIY intake muffler. One easy option is replace that PVC pipe with about 5' (just a swag number) of rubber hose. Then put the intake filter at the end. The rubber hose can pulse with the intake chuffs of air and help deaden the sound that makes it through the air intake.

Once they get over about the 5hp mark with single phase, they have to be hard wired in.

This is true running HP, not the advertised peak HP ratings you see on cheaper compressors.

I think you are allowed to have even larger motors on a plug but the plug has to be rated for an x HP motor which most aren't and those that are cost a lot. example -> https://www.ebay.com/itm/Hubbell-460P9W-Pin-Sleeve-AC-Plug-Connector-60A-30-5HP-250VAC-/153341354677
Hence most people say 5hp needs to be hard wired.

 

[theoldwizard1]

There is a beautiful looking 2 hp green Sears compressor near me. It must have only been used to up up tires because it looks brand new ! $60

Of yeah, a couple of oin holes in the bottom plugs with JB Weld. Well you know where it will start leaking and you really don't need to worry about the tank exploding !

 

[BFBOB]

I second the 5 gal. bucket notion for intake quieting. Mine came (used) with no intake at all, so I fabbed up a pipe and two discs to sandwich a round paper cartridge AF. Noisier than I liked, so I put a a 5gal pail over it, with a strip of foam rubber around the top and bottom to hold in place. Cut the noise at least in half (-10 dB) for free ($0).