Craftsman Air Compressor Help

[inane2]

Good evening guys,

My vintage 14 gallon Sanborn pump laid down on my this weekend (I'll save that for another thread!) I have a new 60 gallon compressor waiting on me in the corner but I'm in the process of a remodel and haven't gotten to the electric yet as I have no 220.

Picked up a 25 gallon Craftsman Professional over the weekend, sweet CL find. It was bought new in 2010 and has lived a simple life in small garage airing up tires, etc.

The owner was selling it because he said it would often trip his breaker. We started it up, built up to 175 and kicked out. We ran it down to 145 and when it tried to kick back in, the motor locked and hummed. He then showed me he turned the switch off, ran the pressure all the way down, turned the switch back on and the compressor fired up and ran back up to 175 with no problems. I quickly bought it up and headed home.

Once back at the shop, I found that the lowest PSI that it will fire back up is 20 psi.

The compressor uses a common D26613 pressure switch but it costs more than what I give for the compressor.

With it's cover off:

I'm thinking the problem is in the unloader valve itself. It really seems like there's still air on top of the piston when it tries to restart.

After travelling to the end of the internet, I found the valve by itself on eBay:

http://www.ebay.com/itm/360747658589?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

Do you all think this is the problem? Anyone know of any other compressor parts suppliers?

Thanks!

 

[kams1973]

You can't tell if it releases air when the compressor kicks out?

You could loosen the compression fitting after the compressor kicks out and see if there is any trapped pressure. You might want to check the capacitance of the start capacitor as well.

 

[The Cobbler]

read this thread, particularly my post #15 http://www.garagejournal.com/forum/showthread.php?t=196633
a cold start or unloader assist valve will probably help your problems
I'll try to get some pics in the next day or so

 

[diebog]

I have that same compressor but a little bit older then yours. When mine reaches its shut off and the motor stops driving, you hear a psssssshhhhttttt. The air being let off the cylinder so when it goes to fire up there isnt a ton of resistance. At least this is what mine does. Does yours make that sound when it reaches the max shut off switch? If you don't then maybe try what kams1973 sugg to crack the nut off the line and see if air reliefs out.

Also there was a recall on some of these units. I got a notice a year or so ago about something with the cylinder/piston and rings that needed to be upgraded. Yours may fall under that recall, I don't know. It might not even be related. Just thought I would mention it.

 

[inane2]

Thanks for all the help guys. Here's an update:

Running the compressor as is, I did not hear a hiss after cut out, unloading the air on top of the piston. I removed the shroud off the motor, built up the pressure and removed the air line that goes into the unloader valve at the pressure switch:





Air rushed out then slowed down but continually came out. However, once I drained the air down to about 145, the compressor kicked in and ran as normal. First time it's done that since I've had it.

I put the air line back in and decided to watch the pressure switch to see if it's actually hitting the unloader valve when it kicks out. Built up pressure, compressor kicked out and a metal plate moved forward to depress the unloader. It acted funny at this part because it still acted like there was pressure and the motor couldn't restart.

Took the screws out of the unloader and removed it from the pressure switch. Hooked it back up the to the air line and decided to experiment.



The needle in the unloader comes out with force when the compressor is running. After it kicks out, I press the needle and bleed the air off. If I hold it in, the compressor will restart. However, if I let it go, the needle pops back out and I can push it back in to unload it once more, but it will pop right back out. So then I removed the check valve in the tank:





Pretty nasty, all rusted up. I put it on the wire wheel, soaked it good with some PB Blaster and put some air (from another source) to it. It opens fine, as it is filling the tank correctly, but it must not be closing all the way creating the leak mentioned earlier. The unloaded valve leaks at its compression fitting if the needle isn't depressed. This will deplete the whole air supply in the tank in about 4-5 hours. Once you depress the needle, it resets itself and pops back out.

I'm thinking the unloader is working fine and that the check valve is the ultimate culprit here. It's like it initially tries to somewhat empty but the leak keeps pressure on it and it never relieves the air on the piston.

Thoughts, suggestions, ideas?

Thanks guys!

 

[inane2]

Ok, found the check valve on eBay and mastertooltrepair.com.

Going to replace it. Some versions look the same, others look different (the valve inside the tank itself).

I'm thinking this faulty check valve is keeping that line to the pressure switch pressurized, even after if releases.

 

[Major Ramifications]

If the check valve is leaking and the unloader is working correctly, then the air would run through the check valve and the unloader when the compressor is off until the tank is empty. If the check valve is stuck closed, then the tank would not fill.
Given the above information, you certainly don't seem to have a check valve problem.

Is the unloader valve being mechanically engaged correctly by the pressure switch?

 

[inane2]

Good evening guys,

An update - I finally got the compressor fixed! As many of you suggested, I replaced the check valve and that instantly cured the problem. Pressure builds up to 175 psi, kicks out, hisses for about 3-4 seconds. When it drops to 145 psi, it kicks right back on with no problems.

We knew the check valve was letting air in and we also knew it was letting a little bit of air back out since it obviously wasn't seating completely. This air was going back into the compressor line and sitting on top of the piston. The unloader valve was doing its thing but the air just kept coming back up out of the tank.

$8 on eBay and my CL compressor is like a new one. I had noticed this seller was really selling this particular model of check valve.





Thanks again for all the help!

 

[lowrodderchev]

You wouldn't happen to remember the number for the check valve would you? I'm currently in the same boat

 

[inane2]

Certainly do and very glad to help!

I keep this listing under my "watched" items:

http://www.ebay.com/itm/20085984583...&ghostText=&_sacat=0&_nkw=200859845831&_rdc=1

Cheap fix!

Mine is still running fine today, I just make sure to drain the moisture out of the tank. I think the original owner failed to do this regularly and it ended up badly rusting the check valve.