Craftsman 4 Gal 1 HP air compressor

6 years 8 months ago #2132 by Hoppy
Craftsman 4 Gal 1 HP air compressor was created by Hoppy
My unit has very few hours on it. It will not build up pressure beyond 28 lbs. I replaced all gaskets and the piston and rings, still no good. Any suggestions?

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6 years 8 months ago #2133 by MTR-Admin
Replied by MTR-Admin on topic Craftsman 4 Gal 1 HP air compressor
Thank you for the post!

I would need your model# in order to see what you have. Do you have the model number or the part numbers for the parts you've recently replaced? If not, you can upload a photo or two of the unit/parts.

The only other reason the unit would not build pressure past 28 PSI is if your reed (flapper) valves are damaged/sticking, or if there is an obvious leak somewhere where the air is bypassing.
My money is on the Valves, most likely they are rusted and sticking to the valve plate, so that they cannot open and close as they should to let air in on the intake and out on the exhaust.

- MTR

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6 years 8 months ago #2134 by Hoppy
Replied by Hoppy on topic Craftsman 4 Gal 1 HP air compressor
Model # is 921.166380. The parts I replaced are on page 9 of the manual. Kit #3 E100251 Piston Kit,
Kit #2 E100959, Gasket kit. I can send pictures later if needed. As for the reeds, they are clean and not damaged, but I can replace the as well if in your opinion they could cause the trouble. Thanks for your timely response!

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6 years 8 months ago #2135 by MTR-Admin
Replied by MTR-Admin on topic Craftsman 4 Gal 1 HP air compressor
The Reed Valves are not available by the looks of it, unfortunately...

The only other reason the unit will only build 28 PSI is due to Rings, Gaskets or Valves....this is barring an obvious air leak somewhere.

You can certainly attempt to find some spring steel that's around the same thickness and cut the Valves yourself...it looks like that's the only option at this point.

- MTR

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6 years 8 months ago #2137 by Hoppy
Replied by Hoppy on topic Craftsman 4 Gal 1 HP air compressor
Actually I have it working now. I sprayed some contact cleaner down inside the pressure switch and that did the trick. Thanks

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6 years 8 months ago #2138 by MTR-Admin
Replied by MTR-Admin on topic Craftsman 4 Gal 1 HP air compressor
Glad to hear it! I should've mentioned that initially but glad you have it working now.

- MTR

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