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Air Compressor Not Filling Up

Levaughn

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Joined
Feb 17, 2015
Messages
1,404
Location
NY
A friend gave me a Central Pneumatic 100psi 1/3 hp 3 gallon compressor. I want to use it for airing up bike tires etc. I turn it on, it runs but the needle does move. I let it run for a few minutes, pull the blow out vale and very little air comes out. I unhooked the hose coming from the motor going to the tank and it blows air. There is a round ball with a spring that sits inside where you screw the hose into the tank. It doesn't seem to be stuck. Is there any place else I should be checking? There was a little water in the tank, and who knows the last time he used it. Thanks.
 
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micromind

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Sep 24, 2023
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Fernley, Nevada, about 30 miles east of Reno.
The round ball thing is a check valve. It prevents pressurized air from going back into the pump so it can start easier.

With the hose disconnected, run the compressor and put your thumb over the end of the hose. It should build more pressure than you can hold.

If it doesn't, look for the unloader piping and/or valve for leaks. The unloader valve is most likely at the pressure switch. They stick open a lot.
 
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Levaughn

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Feb 17, 2015
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1,404
Location
NY
Thanks for the replies. I unhooked it from the tank and started it. Although it's pushing out air, I can hold my thumb on it without it pushing it off. I took off the head and saw the piston wall was scored. I don't know if it's bad enough for it to not push out strong air.
 

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American Locomotive

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Jan 8, 2017
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Rhode Island
Looks pretty toasted to me, but I'd expect it to build some pressure. You might be able to get a replacement piston and cylinder from Harbor Freight if you have the model number of the compressor.
 
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Levaughn

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Feb 17, 2015
Messages
1,404
Location
NY
Looks pretty toasted to me, but I'd expect it to build some pressure. You might be able to get a replacement piston and cylinder from Harbor Freight if you have the model number of the compressor.
Thanks. I was looking around on the internet for parts but haven't come up with anything yet.
 
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