Curb pickup air compressor, can it be repaired?

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MontanaLon

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I was driving my son back from a Scouting event when I saw an air compressor, about a 20 gallon model, someone left at the curb. Always in the mood to scrounge junk I pulled over to see what was up. The homeowner who had put it out was outside putting up Christmas lights, so I asked if he was getting rid of it and he said he was and I could have it. So, I made the son load it up while I talked to the previous owner. He said it had made a noise and then made a lot of noise and he shut it off. When he turned it back on same noise so he went and bought a new compressor. This one has some age on it, just a Campbell Hausfeld oil-less so it is nothing special, but it was free. When I got it home I pulled the cover off and the piston dropped out as well as some plastic. Looking online the plastic was the cooling fan and there are no parts available for it.

The piston is broken through the crank end, if I had to guess the bolt that clamps the crank around the bearing got a little loose, or the bearing is worn out and it got a little sideways and self destructed. I am sure it made a hell of a noise. The bearing seems to turn ok but has some scuffing on the outer race from things bouncing off it. The motor runs like a champ and the tank is solid. I pulled the cylinder off and it is in good shape. So now I am considering how to do a repair to get it running again. Over the summer I grabbed a 5 gallon compressor off the side of the road with a 1,500 watt generator. Both work, just not together. But the compressor has blow by issues and after it starts running it blows off the oil plug at random intervals, not ideal, so a new free compressor would be nice.

So, I am looking at ideas to make a new piston which seems a whole lot better idea than trying to repair the busted one. I could go a couple of routes with it. Whittle it out of bar stock. It is 2-3/4" across and 5" long so could be doable but would mean hogging off a ton of aluminum. Or I could cast up a new aluminum piston which wouldn't be too hard with lost foam. With either of those options I have to figure out how to make it seal inside the cylinder. Right now the piston has a plastic of some sort cup style seal on it sandwiched between the piston body and a staked on steel washer. What sort of plastic would that be? It has to have some elasticity and stand up to some heat and not wear out fast. Was thinking nylatron would work but then I think about it and it may be easier to just lop the head off the piston and reuse the seal that is there after machining up a new rod for it.

Or I could just yank the pump off and repurpose the tank as the start of a new furnace for melting metals to cast because it is quite literally the perfect size for that.
 
Doesn’t sound like it’s worth fixing. Repurpose as best you can and hold out for something worth rebuilding.

John
 
Make a piston and jump on the o ring store for a seal to fit........OR just re purpose
 
It is almost certain that there is wear in the cylinder and crankshaft. I am sure it could be repaired / rebuilt and equally sure that it would require more than just a piston and connecting rod. Consider buying a new pump to use with the existing motor and tank.
 
IMHO, oil-less compressors are pretty much disposable, as they inevitably wear out and fail, and parts for these machines are almost never available.
However, if you are up for the challenge of seeing if you can fix it, it could be worthwhile.
No shame in scraping it and reusing the parts, either...
 
Assuming you have the storage, this sounds to me like a potentially useful collection of scrap bin parts.;)

Air compressors are potential bombs and my father (who was a skilled mechanical engineer) once warned my uncle against taking an old, somewhat tatty air compressor from a work mate with the words (or something close to) "if something on it lets go, you could have a bullet flying around your garage. If the tank lets go, that could be shrapnel"

To be fair, I suspect my father's biggest problem was that my uncle's first step on getting the compressor, would have been to ask him to sort it out into a usable and 'safe' state. Dad was not that keen on any of my mother's family and not inclined to seek out the extra work, especially from them. :grin:

Still and all, even 'working' compressors bought secondhand for money ought to be tested and serviced by someone who knows what they're doing (and sure, you may well have those competencies). Something found scrapped sounds like more work than it's worth to be confident that it'll be safe and reliable.

The tank, if hydro-tested and in good order, might be useful for expanding the capacity of an inexpensive but decent bought compressor (new or used).
 
As a fellow junkyard dog it’s hard to pass up free but I know all too well it can end up a worthless time sink. I don’t mess with oiless compressors as I was told by those in the biz they were basically consumables. Same with the tanks unfortunately. Too many tools now are that way.

Case in point was trying to fix a craftsman tablesaw (my dad gave me)with an all cast iron top and wings. As I was trying to turn it over it got away from me and fell onto a 3/8” rod that was supposed to support the blade guard. Didn’t know that rod is the pivot for the whole chintzy sheet metal arbor that attaches to the top. When it hit it jammed the rod back and broke the rear pivot mount that was a chintzy piece of sheet metal. I could find the part but was long out of production and cost a whopping $3 but completely unobtainable. So I had a piece of solid aluminum stock and reproduced the shape and holes on the mill. But not after trying to figure if this was worth the effort. In trying to find parts I had to go through the many iterations of the once venerable craftsman 113 series saw and it was truly heartbreaking to see how they had turned a once cast iron arbor into an amazingly complicated sheet metal POJ over its long run. No wonder craftsman and Sears are circling the toilet. And all stuff you couldn’t see from the outside.
 
First thing I would do with any old compressor is to hydro the tank. I have split a couple of old tanks already during hydro. If there is no tank the rest is not much use.
 
SouthernChap said:
(and sure, you may well have those competencies). Something found scrapped sounds like more work than it's worth to be confident that it'll be safe and reliable.

The tank, if hydro-tested and in good order, might be useful for expanding the capacity of an inexpensive but decent bought compressor (new or used).
Click to expand...
I do. Firefighter by trade and we test the hoses which are in the same pressure range as a compressor tank so that is no problem. The test rig even has quick couplers that will fit on the air compressor for the test. I am still on the fence about what to do and have other projects in the works so it may take a bit to get around to it.
 
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