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Craftsman oilless air compressor not pumping

Hi friends! Dne’ here! My brother “Robo”, bought one of the oilless air compressor went out. He uses this compressor at his car wash to run his foaming brushes. You know, when you turn on the brush at a coin operated car wash, the foamy soap comes out? The compressed air makes this happen! Didn’t know that did you! ; )

I suppose that most oilless or oiless (however it’s spelled) air compressors work on the same principle, however, I’ve never opened  one up to see what makes one tick! I’m intrigued!

When Robo first got this compressor, darn it was noisy, but did the job for a year. These are noisy compressors! The only maintenance would be draining the condensation or checking the air filter, other than that, there is no maintenance!

I do like the portability of this compressor, just roll it around and takes up less space than the horizontal compressor.

Here we go! we removed the plastic housing, and to my dismay, this is the pumping mechanism! “That’s it!” I say! I’ll have to say it’s kind of squirrelly!  At this point, we had already taken it apart, I just re-assembled it for this blog.

Once the head is unbolted, a cylinder sleeve will slide out and the geeky piston is now revealed!

Here’s the counterweight that makes this compressor run smoothly! ha! It would vibrate your teeth out! On the end the shaft here is the “connecting rod bearing” for lack of better description. This one is ok. It could run smoother is the machine was balanced and blueprinted! lol (seriously).

I think here is what may have short-lived this compressor. The air cleaner screws onto here(below pic). It’s pipe thread in aluminum and destined to wear and vibrate out. I asked Rob, “where is the air filter assembly?” Well, it’s nowhere to be found! However, these threads are stripped out and a new head had to be ordered.

From left to right: cylinder head, reed valve assembly, cylinder, and piston/rod.

In this pic below, the Teflon piston ring is the culprit of why it doesn’t pump any more! I figure that the Teflon ring wore out due to contamination, then devoured the cylinder wall ruining the cylinder.

However, one cannot just buy the Teflon ring, you have to buy the entire assembly(piston, rod, cylinder), and we had  to by another cylinder cause ours  was damaged due to the piston beating the hell out of it!

Sears parts is a pretty cool site, but I couldn’t find some of the parts online, so I called Sears. The really nice guy there helped me figure out what we needed. It came out to about 134.00, still cheaper than a new compressor!


Below: The new air cleaner installed~ I applied some red loctite so hopefully it won’t vibrate and fall off this time!

Here I’m about the re-install the cylinder head. Be sure to put the reed plate on correctly!


                                   Click~ Exposed view of compressor running ~Click!


Well, we’re not out of the woods yet! The compressor isn’t holding pressure and sounds like it’s leaking at the pressure switch, but, see that brass fitting in the picture below? That is a one way valve to keep pressure in the tank. The plastic seating valve inside of it is worn and allowing tank pressure to leak back to the pressure switch and create unwanted head pressure! The leak is ultimately coming from this fitting! So, called Sears again, and ordered this 9.oo dollar part~ shipping was 12.00! ; )  If this fixes it, we’ll be good to go!

I found this compressor to be interesting! ; )  I love taking things apart to see what makes them tick! don’t you?  I hope you’ve found this interesting as well, and please check out some of my other blogs~ hopefully there’s something that may help you! ; )  Oh, don’t forget to subscribe to Classic Cars and tools! ; )   dne’


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7 Responses so far.

  1. Dave says:

    I have one of these type of compressors and always wondered what they looked like disassembled. Fortunately, I haven’t had to take mine apart. Thanks for posting your findings.


    • admin says:

      Hi Dave! I’m pleased that you liked my write-up on the oilless compressor! I have my own series of “how it’s made?” a mini series! ; )

  2. wayne says:

    I do have a question regarding your post. Obviously you didn’t have to replace any parts in the head itself. Well I’m looking for just the reed valves because they’re attached with a small screw inside the plate. Do you know where to get these parts which will save me money I’m sure?

  3. wayne says:

    I’m looking for just the reed valves inside my craftsman compressor because they’re attached with a small screw inside the plate. Do you know where to get these parts which will save me money I’m sure? If you know you can e-mail me at wdollinger@youhoo.com

    • admin says:

      Wayne, If I remember correctly, I had called Sears parts and spoke to a gentleman there about the parts. Personally, I was just wanting to replace the teflon compression ring, but they don’t sell parts individually. If I wanted the piston ring, I had to purchase the entire piston. All in all, it really needed all the parts, including the head.

      There’s an air cleaner which screws into the cylinder head by pipe thread. Over time the air cleaner vibrated and messed up the threads in the head, resulting in needing a new head. I believe the new head came with the reed valve, but it’s been quite a while since I had done this “overhaul”.

      If I were you, I’d call Sears parts, or possibly look on their website and look through their parts specific to your needs. You will need your model and serial number, so have that handy. On the website of sears, you may at least be able to identify that reed in which you speak of.
      btw, the parts were fairly pricey, almost half of what the entire compressor costs:(

      I hope this helps~
      let me know how it turns out!


  4. James Gerber says:

    I have an air compressor that I used about 5-10 times per month. After each use, I empty the tank and leave the valve open to allow for the water to drain out. I really don’t like having fill the tank prior to each use, but I have heard that this is a required step to protect my air tools. Is there something that I can do to keep the air in the tank and still protect my tools?

    • admin says:

      Good morning James! I rarely let all the air out of my compressor as I use it frequently, but a good filter/dryer is a necessity in providing clean, dry air. Condensation just happens during the operation of a compressor and in higher humid areas, even worse, like here in Houston. When installing a filter/dryer, it should be far a way from the compressor to allow the condensate to turn to droplets which will be caught by the air filter. Though I haven’t gotten around to it, a maze of piping can be made to facilitate the vapor into water. After that, then just general care would be taken to oil your air tools before each use. If all you use is air tools, then there are inline oilers to provide that without thinking about it. I use the one below, but only for reducing water, but I do spray paint fairly often and do not want oil in my air lines!;) But again, the dryer must be far away from the compressor to allow water vapor to condense. Even then, I still have water vapor coming out of my air line like when using a blow gun. So, in a further attempt to reduce moisture, I use a disposable filter right at my spray gun. But your concern is mainly air tools? I have a 90 degree fitting under my compressor bring the valve to drain my compressor much easier. If you’ve noticed, or in my case, rusty water comes out, which in time I suppose will short live the compressor tank, so I’ve thought about using evaporust or something similar to neutralize the rust inside the tank. Haven’t gotten there yet! On my list of to do’s! Hope this helps! the internet has a write-ups on how to reduce water vapor. Let me know what you come up with.
      dne’ 😉