The compressor only reach 50 PSI.

This problem is usually caused by reed valves or blown gasket between head and valve plate. Easy to check. After the compressor reaches 45 to 50 psi, with compressor still running, remove the air filter and feel for good suction at the intake port. If the air seems to be blowing out of the intake, then valves are bad. If you feel good suction at the intake, then air is leaking from the discharge tubing or other fittings. Good luck

Hi, There are different posibilities. I would need more information. Was it always like that? Does the guage on the main tank and the guage on the regulator both not show more than 20psi? When the auto shut-off is triggered do you feel there is more than 20 psi in the tank?

Cbillgreene:

Your compressor is leaking air somewhere between the compressor head and the tank. With the compressor running, feel carefully around the ends of the tube that leads from the compressor head to the air tank. You will probably feel some air leaking around one end or the other. If so... remove the tube and find out which packing has failed.

If you had shrapnel in the top of the piston, you probably have pieces in the wall and the rings are probably bad. I would tear it down look at everything from the top down to the cylinder or block. if there are gouges in the wall it will need to be honed if they are not real bad, otherwise replace it. Certainly replace the rings and inspect the piston as well. If you have the Italian pump it would be worth fixing, if not it may get costly. Also inspect all your gaskets and valves. You may also have shrapnel in your infeed tube which may get to the Non-Return valve and cause it to stick open and bleed off pressure. If you can post more details I maybe able to help you further.
Tim

You suspect this unit as being a two stage because of the unusually high cut off pressure. It is a single stage and the motor really has a difficult task and is being pushed to the limits. to reach this pressure. We usually reset the pressure to lower setting ~~ say around 140. Your pump probably has a leaking intank check valve (brass fitting at tank) or leaking valve plate in pump. Simple tests : with pressure in tank unplug compressor from outlet and listens for air leak around pressure switch. As you unplug the running compressor from outlet you should hear air leaking from pressure switch for just a moment as air is let out of airline from pump to tank. If air leaks out till zero pressure then change the valve. If tank holds pressure then valve probably ok. Next test, with no air in tank and air filter removed, plug in compressor and feel intake port for strong suction. If the valve plate is bad, suction will decrease as pressure neers the 120 mark till the point of feeling that air is actually blowing out of intake. With good valve plate there will be strong suction untill unit reaches set pressure. If valve plate is bad also change the cylinder and piston ring. Good luck with your repair.

Did you replace the expansion valve?
Also try adding just a little more freon and see if that makes a difference....is there a sight glass you can view with the system activated to be sure you have it completely air free?

Leave the compressor setting to the highest level.The other guage is to regulate the pressure output.For example if you need 40 PSI turn this regulator until this output is reached

you need a higher pressure discharge valve to reach more than 50 psi.

Check to make sure that the regulator is set to the proper setting. You need to turn the knob clockwise to increase pressure. This is opposite of a valve which you turn counterclockwise to open.

Post a comment so we know how you did.

Thanks,

Tim

i am assuming this is an oil less compressor as I have never seen a crapsman compressor that is not
you need to feel around the head and see if there is air leaking anywhere usually around the tube that goes to the tank or the pressure relief valve