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Air Compressor problems

Post in 'DIY and General non-hearth advice' started by nshif, Mar 8, 2008.

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  1. nshif

    nshif New Member

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    I have a Devilbiss Air Comp, 5hp, 25 Gal. about 6 yeqrs old with a fair amount of use on it. Has always run well but in the last few days it wont make enough PSI to shut off with no load (off at 120 psi) What do you think, is it worn out or is there something I could look at. I tried removing the air filter to see if that was a problem but it didnt help and there are no signs of air leaks.

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  2. grizzly2

    grizzly2 New Member

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    There are reed valves that are metal strips that flap up and down to let air into the cylinder, then shut to hold the air in the cylinder as it is compressed. The reed valves can usually be seen by removing the air filter. Perhaps some models will require removing the head. They can warp or break, but I believe it is more likely dirt has gotten under the reed vavle so that it is not closing all the way. I bought a small compressor real cheap once, and that was the main problem it had.

    If you are not confident in doing the job yourself, most engine mechanics and all small two cycle mechanics can fix this for you. Labor should not be too much. Good luck. :coolgrin:
  3. nshif

    nshif New Member

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    Well pulled the head and the reed valves look fine. Also pulled the check valve at the tank and it seems fine as well. cylander wall doesnt look so good so I suspect the "rings" are shot and compression is reduced to 40psi which is all I can make.
  4. Redox

    Redox Minister of Fire

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    It sounds like the pump is shot. If the tank and motor are in good shape, you could replace the pump with a new one, but I suspect that the price may be close to the cost of a new compressor. Beware the HP rating if you replace anything. Most manufacturers are rating their compressors for peak horsepower which is unrealistic. Compare the CFM rating at a given pressure (ususally 90 PSI) to compare apples and apples. Good Luck!
  5. lobsta1

    lobsta1 Member

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  6. nshif

    nshif New Member

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  7. drizler

    drizler Minister of Fire

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    Take those motor ratings with a big big grain of salt. That 5 hp is something like a 3 horse in the real world. I have 6 hp Campbell Hausfield and its pretty much junk incapable of running much of anything. . From your description you have a direct drive type not the older cast iron motor and pump connected by a belt. Those direct drives put out a lot more air for the motor size but they don't hold up nearly as well in the hard run haul. You probably rand it too hard too long and it cooked the rings. Thats why the older type is preferred for most garage service usage. The directs will work but just watch how long you let it run continuously. Sand blasters, even small ones, and HVLP spray guns and such are best used sparingly. You can cut down on some run time by plumbing into a separate tank like an old propane tank to cut down on cycling but its really not a solution if you want to run paint guns and large air tools.
  8. nshif

    nshif New Member

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    Tore it down all the way today and the "rings" (only one ) is shot, big piece missing. Ordered a new "piston" cylender and seals today for less then 40$ so not to big of a deal. I dont run high volume tools much, mostly air nailers etc. High volume stuff is pretty limited.
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