Compressor won't compress

[law_kid]

My compressor seems to stop compressing when it hits about the 85-90 psi mark; the motor keeps running, but it won't build up any more pressure than that. It's a Craftsman 3hp unit, 15 gallon and 150 psi, about 12 years old. There are no leaks anywhere; drain plug is fine.

Any ideas what this might be? Has the motor gone bad?

[JGrout]

My compressor seems to stop compressing when it hits about the 85-90 psi mark; the motor keeps running, but it won't build up any more pressure than that. It's a Craftsman 3hp unit, 15 gallon and 150 psi, about 12 years old. There are no leaks anywhere; drain plug is fine.

Any ideas what this might be?  Has the motor gone bad?

well the motor cannot be bad as it continues to run

is the compressor oilless or oiled? the fix is dependant on the compressor head design

[TDKPE]

is the compressor oilless or oiled? the fix is dependant on the compressor head design

And is it belt-driven or direct-drive?

[law_kid]

well the motor cannot be bad as it continues to run

is the compressor oilless or oiled? the fix is dependant on the compressor head design

And is it belt-driven or direct-drive?

Oilless. And direct drive (from what I can tell).

[daddo]

Oilless. And direct drive (from what I can tell).

 No idea what you have.

Look at this.

[John Mihich]

 No idea what you have.

Look at this.

 Yep on the piston for oilless.  There maybe thin valves that open and close - I know on my oil compressor I had to replace them.

[law_kid]

 No idea what you have.

Look at this.

That's the exact model I have!  Thanks for the video.

[TDKPE]

Oilless. And direct drive (from what I can tell).

That lets out belt slippage.  Sounds like worn rings (or whatever the piston in an oil-free type has) to me, too.

[woodhead]

Usually a rebuild kit fixes the problem...bad piston ring.


Al