Restoring an Air Compressor

[Ryan Ellis]

Hi All

I need some help fixing up a compressor I was able to buy that had been sitting in someone's yard for about a year. It's a 60 gallon, two cylinder, horizontal model, with no markings except serial numbers on the compressor portion. I guess its been repainted, including the motor.

I have two questions.

1. The plug is a 110V plug, but I would think it should run on 220. Is there a way to tell the voltage of a motor with no markings, and no voltage conversion terminals under the access panel? It has two wires and a ground going to the motor.

2. This is an oiled compressor with some water in the cylinders. What should I do to fix the compressor? Is there somewhere I can find a complete procedure to do?

Thanks in advance for all your help!

Ryan Ellis
Jacksonville, FL

[Kevin Gerstenecker]

Ryan, was this compressor covered as it sat outdoors? If not, the motor is probably ruined. There should be a information plate or sticker somewhere on the motor. You should be able to locate it, and it would tell you if this is a dual voltage motor. Without looking at the wiring terminal under the cover, it is hard to say if it is dual voltage. My guess would be that a compressor of this size would be a 220V application. If the Plug is a 2 prong with ground, and one of the spades is horizontal instead of the normal both vertical 120V application, it could be a 220V plug. A normal 120V plus appears as such: l l and a 220V 3 prong: l - , with both having a ground terminal on the plug. As to the water in the cylinder, that is a bad thing, especially in cold climates, where the water could have frozen, and cracked the cylinder. If there is not a lot of rust on the cylinder wall, you could probably get by with a liberal dousing of a penetrating oil to free up the piston rings if they are rusted and stuck. If the cylinder wall is rusted, you would have to hone the cylinder and replace the rings. Air compressors are a bit of a strange animal, and without laying eyes on it and inspecting it, it is really impossible to say what sort of attention or overhaul it needs. I would take the Compressor power head to a business that services Compressors and see if they can identify it, and lead you in the right direction. They may even check it out for you at a minimal cost, and tell you if it is even salvagable. Good Luck, let us know how it turns out.

[JayStPeter]

if it runs on 110, it's most likely not worth fixing up. If it runs on 110, it's probably less than 2HP. BTW, don't confuse 2 cylinder with 2-stage when comparing to new ones. If you do have a 2-stage, then it may be worth a try to fix up.
Like most things, buying a compressor piece by piece is much more expensive than just getting a new one. I started to refurb an old Speedaire 2HP compressor (that only ran 220V). It was a nice, relatively quiet compressor in it's day. But, it would've cost $200 for the compressor stage (cheaper than just replacing the heads that were trashed). Plus the seals, belt and other small things, it didn't have the specs to make it worthwhile. Even though it was an $800 compressor new, one of the $250 oilless would do everything it could, just louder. I finally drug it to the dump when I needed a spot for my drill press.
If you plan on going through with it and the motor runs, it sounds likely you need a new compressor stage (since your cylinders are full of water). Check Grainger, they have a large selection.

Jay St. Peter

[Mike Vermeil]

I ran into the same thing. An old industrial style compressor I had actaully sprung a leak in the tank due to rust (I always thought all that talk of rust-induced explosions was nonsence - no more!). The price of a new tank was almost as much as for a new compressor. Granted, the new comp is oil-less and noisy, but it's new, came with a built in regulator, and doesn't require any attention.

If you watch, you can get deals from Sears on new compressors with spray guns, air wrenches (always handy) and all kinds of extra junk thrown in for basically nothing.

[Ryan Ellis]

Thanks all for your opinions.

The motor has zero markings and their are no conversion terminals to switch voltages. It was left outside, but does at least turn over on 110. But I've never let it reach operating speed, so I don't know if thats the correct voltage.

I guess I'll have to crack open the compressor head and investigate more.

BTW, what is the difference between two cylinder and two-stage. The cylinders are different sizes on this one.

Ryan

[Mac McAtee]

Ryan,
If the two cylinders are different sizes it is a two stage compressor. The larger cylinder compresses the air in it and sends the commpressed air over to the smaller cylinder, it is smaller because it is taking air that the larger cylinder has already compressed and there is less volume. If the secondary cylinder were the same size then the air would decompress back to it's orginal volume. The second, smaller cylinder then compresses the air again and feeds it into the storage tank.

There should be a pipe from the larger cylinder to the smaller cylinder for the air transfer as it is compressed.

[Ryan Ellis]

I pulled off the head, then the cylinders themselves last night.

There is rust, but not as much as I expected. About a 1/4" ring around the top of the cylinders, and a few spots further down. The pistons have a little rust underneath the rings. The pistons were never stuck, and the rings all look good, but I've never checked out rings before.

I see where someone removed the motor identification plate and only the rivets remain. Also, there are no terminals under the cover.

Jay, what was your compressor like when it was trashed. I want to know if mine is in as bad condition as yours was.

Mike, can you give me some more details about the rust leaks? What happened when it popped, and could you see any signs of rust?

Thanks Again

Ryan Ellis

[Mike Vermeil]

Ryan,

I was lucky on the rust hole in my tank. I came out into the shop one day to find water puddled on the ground. I assumed it came from under the cement wall that my compressor sat against since it's below grade, and didn't think too much about it. As I was mopping up the water, I noticed it was a bit rusty, and then glanced up at the bottom of the tank just in time to see a drop of water forming. Too say it was a pin-hole would be an exageration. You almost needed a magnifying glass to see it. A drop of water would fall about every 45 seconds or so.

I don't know if it would have exploded or not, but I've heard stories of that happening and am glad it didn't happen to me.

The compressor was a 20 year old Speedaire knockoff, and the morons that had it before me never drained the water.

[JayStPeter]

Ryan,

My compressor was totally different than yours. The motor and tank were in pretty good shape. The flapper valves on the head had popped loose on one cylinder and thrashed the head. There was a screw impression on one of the cylinder, but it probably would've been OK. The head itself was incapable of ever holding the flapper valve again.
Someone had taken it apart at work and determined the head was trashed. The company bought a new oil-less and gave me the old one. They had also lost the small pipe from the compressor to the tank. New head was $130 and the seal kit was $50. Or, a new compressor stage was $189.
If yours is 2-stage, it may be worth saving (never heard of a 2-stage that runs 110 before). I guess you'll have to see how well you can clean the rust before making the determination. The cylinders need to be at least reasonably smooth to compress.
A friend who restores old machines and resells tells me that his rule of thumb is a true 5HP or larger compressor is the least he'll bother with. I thought that I would be able to restore the one I had for the $50 seal kit. Once I realized that I was looking at closer to $250, it became way less desirable. Got a good 2HP motor and magnetic switch out of the deal though.

Jay St. Peter