Air compressor issues

Jackman

Jackman

TJ Enthusiast
Joined
Aug 5, 2018
Messages
252
Location
Mt morris,mi
Today at work I found this beauty..

Mid 1980's Craftsman 2 hp with a 20 gallon tank . Runs and tank holds air. But......if there is already air in the tank, the motor does not turn the flywheel.. can not even turn it by hand.
Any ideas?

IMG_20181212_121125924.jpg
 
Jackman said:
Today at work I found this beauty..

Mid 1980's Craftsman 2 hp with a 20 gallon tank . Runs and tank holds air. But......if there is already air in the tank, the motor does not turn the flywheel.. can not even turn it by hand.
Any ideas?

View attachment 67563
Click to expand...
Pressure switch unloader is bad most likely. If you listen to most air compressors, when they reach the target pressure, you can hear the sound of air being released which removes the pressure from the compressor head so it isn't starting under load.
 
That's what i was leaning towards.... There's a valve on the head that is hissing a bit. After getting the air out of the tank it starts and runs fine.
 
After some research, I found that the pressure relief tube is missing and obselete.. so looks like to make it work properly I'll have to rig something up.
 
I recently repaired a friends compressor that had the exact same issue your describing. The check valve at the tank was bad. Cheap repair too. The valve was less than $10
Easy to check also. Run the compressor until it shuts off. Loosen the tank end of the aluminum colored tube at the tank. If you hear air escaping, the check valve is bad. This is a very common air compressor problem. Many air compressors are discarded instead of being repaired because of this easily replaced part.
 
Last edited:
Yup, unloader. A universal type should work for that. The idea is to have zero psi from the pump to the tank, gives the motor a chance to start without pressure.
 
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