diagnose compressor issue

[Eazy716]

Hey guys, I'm in need of a little help trying to diagnose a problem with my compressor that popped up last night.

I have a Craftsman 25 gallon compressor, similar to the one pictured here...

Last night I kicked it on to fill, and walked in the house to get away from the sound. Came out about 10 mins later when it should have been filled, and it was still running. I looked at the gauge and it was only at 40psi. It was at 40psi when i kicked it on. So it's not compressing any air, yet the motor was running that whole time. I tried to listen for air leak, but couldn't hear anything. You would think air leak would have been pretty audible based on how long it was running.

I know this is a pretty vague account of the incident, but I'm not sure where to even begin to look.

Anyone have any random ideas of possible problems?

Any help is appreciated. Thanks in advance.

 

[sierrascout]

Sounds like the check valve is bad.

 

[Nealcrenshaw]

You definitely should be able to hear the leak @ 40p.s.i
Not sure but if all else fails take it to sears to have it repaired.
My guess would be either the check valve is plug or a problem with the motor

I also have a Craftsman compressor the vertical 33Gal,and if anything seems wrong,to the point where its malfunctioning its going into their shop

 

[Major Ramifications]

Either the check valve is not sealing, or the piston seal is leaking. If the check valve is leaking, you should be able to hear an air leak when you turn it off, because then the unloader valve will open. Since this is not the case, and because I have seen several of these compressors do this, I would vote that the piston seal is leaking. Fortunately, it is not hard to fix. Punch in your complete model number into the sears parts site and see how much the piston seal is. It might not be a bad idea to get a new cylinder, but it is probably not imperative. Take it apart and check the piston seal. You will probably see a small piece missing or worn away on the perimeter. If you can't get the parts from Sears, try devap.com.

 

[rsanter]

I have seen those under their cover and there is not much to them
remove the cover and then run it to see what you can.
post your findings are we can try to help some more

bob

 

[Packard V8]

Begin with a squirt bottle full of thick, soapy water and squirt it all over, every fitting, every joint. The last one of those noisy little POS I worked on, the pressure adjustment valve had vibrated loose and was leaking past the O-ring seal under it. It did exactly as you described; went up to 40 PSI and whistled like a teakettle when one's ear was right by the valve. The compressor itself is noisy as the hammers of hell, so standing away from it, the leak could not be heard.

thnx, jack vines

 

[volvo420coupe]

Make sure there is nothing blocking the air intake, I know this is obvious but thought I would mention it anyway. My clarke upright compressor will not turn over and blow a breaker when its less than 35 degrees, so every time I had to kick it on in the cold, I would put my thumb over the air intake hole on the filter, let it get spinning, then let it have some air, by the time it got all charged up it would be warm enough to kick on by itself again as long as I was working. (My garage would be warming up at this time also, so that helped it out too)