Need compressor help

[reman]

Hi everyone. I haven't posted here in quite some time, but now I need compressor help again. I have an old portable (30 gal maybe) Campbell hausfield. It is the typical 2cylinders, single stage, aluminum pump. Actually I pieced it together from a bunch of parts I bought. Anyway, the problem is that after it runs for about a minute, or less, it acts like back pressure is overpowering the motor and it starts to stall out. I pulled the compressor apart and did not find anything obviously wrong, so put it back together again with a known good motor ( though it had not been run in about 6 months} and it was the same thing again. The check valve in the tank checked good. Can anyone shed any light on the problem? Thanks

 

[TRWham]

Sounds like you’ve already diagnosed it. When you pieced it together, perhaps the motor you used was not big enough. Are you sure the motor has enough power for the pump? Do you know the displacement? Do you know the motor power or amperage?

 

[reman]

Sounds like you’ve already diagnosed it. When you pieced it together, perhaps the motor you used was not big enough. Are you sure the motor has enough power for the pump? Do you know the displacement? Do you know the motor power or amperage?

The first motor was from an identical compressor, though I could not read the specs on it. It was 4 hp I believe because it was identical to the bad one. The good motor I used secondly is 6 hp that was pulling a larger compressor. No, I have not checked the power draw. Will check that tomorrow. Thanks

 

[gotham]

Are you building pressure in the tank? Try running with the tank drain open. Plugged or kinked lines? How about a picture?

 

[Handyfarmer]

I had a compressor that acted much the same, some dirt got in the "check unloading valve" and was nearly plugging it when pressure started to build up thus the pump was trying to push 150+ pounds of pressure in to an empty tank,

take the pipe off at the compressor and run it,

go down to the next location, and see if it runs fine,
and then even take the check out of the tank and run it,
see if you can find the location (if there is a blockage),
if the motor stalls out on the pump no piping, then most likely it the motor or some damage in the pump,

 

[redmondjp]

Check valve going into the tank stuck open?

 

[reman]

Check valve going into the tank stuck open?

Check valve checks out fine.

 

[Citation]

Are both motor caps good?