Compressor woes

[Rennie Heuer]

What do you know about compressors that are not working properly?

I have the 4 gal 2HP staked tank Hitachi. It served me well for many years until recently. It pumps up fine, shuts down at 125 PSI as it should, but as soon as the motor shuts off it bleeds air till it's almost dry and usually pops a breaker trying to restart. I thought it was the switch unit and I replaced that, but no improvement.

Could it be the safety valve? I understand over time that they can weaken and discharge at too low a pressure. I'm just looking for a corroborating opinion before I drop $30 on a new valve.

 

[Ted Calver]

No help on the safety valve but I have a stacked IR that did something similar. Called IR and they said these were not fixable, so I took it apart and found something on the circuit board that didn't look right, fried as I recall....it's been a while. I found the correct number of the part on alibaba and ended up with ten for small money and a few weeks time. Replaced it and the compressor has run fine for the last few years. One caution the IR tech gave me was to never run the compressor on an extension cord because the drop in power could mess up the board. Don't know why but I've followed that advise and it still keeps chugging.

 

[Ryan Mooney]

You can check the drain valve with a bit of bubble solution, I don't think that's your problem though.


From what I'm reading.. on the tripping part. If you open the safety valve all the way and it always starts then it's likely something around the unloader / check valve interaction.

My best guess based on your description is probably a bad check valve which is bleeding air back up into the top of the head and then out through the unloader valve. This would explain both the hard start (high load on start) and the bleed down.. but it could be something else clogged up in that assembly.

This video explains what I *think* is probably happening fairly well.

 

[larry merlau]

i agree with ryan. but if yu cant get parts i might have a used one.
or buy a new compressor,

Metabo HPT EC99SM 4 Gallon Portable Electric Twin Stack Air Compressor, A-Grade Reconditioned

The EC99SM twin stack compressor features an oil-lubricated cast iron pump and 15 Amp direct-drive induction motor for long life. The motor is protected by a thermal overload protection that stops the motor in a possible overheating situation. Weighing just 52.9 lbs., the EC99SM also comes with...

toolsteal.com

 

[Rennie Heuer]

No help on the safety valve but I have a stacked IR that did something similar. Called IR and they said these were not fixable, so I took it apart and found something on the circuit board that didn't look right, fried as I recall....it's been a while. I found the correct number of the part on alibaba and ended up with ten for small money and a few weeks time. Replaced it and the compressor has run fine for the last few years. One caution the IR tech gave me was to never run the compressor on an extension cord because the drop in power could mess up the board. Don't know why but I've followed that advise and it still keeps chugging.

No electronics on mine to speak of. I replaced the entire pressure switch assembly only salvaging the fittings and gauges from the old. Did not improve the issue.

You can check the drain valve with a bit of bubble solution, I don't think that's your problem though.


From what I'm reading.. on the tripping part. If you open the safety valve all the way and it always starts then it's likely something around the unloader / check valve interaction.

My best guess based on your description is probably a bad check valve which is bleeding air back up into the top of the head and then out through the unloader valve. This would explain both the hard start (high load on start) and the bleed down.. but it could be something else clogged up in that assembly.

This video explains what I *think* is probably happening fairly well.

This is a very fast bleed down and I can feel the air exiting at the back of the pressure switch assembly. Definitely not the drain valves. When the unit turns off at 125 PSI it blows air out the back of the switch assembly very quickly, draining the tanks in under a minute.

After watching the video I went back and turned it on allowing it to build pressure. It started to blow out as soon as the motor stoped so I gave the check valve (did not even know there was on) a few quick raps with a wrench. It did not stop bleeding down but it slowed substantially. So, looks like it is not the safety valve, but it may very will be the check valve, or 'non return valve' as noted on the parts list.

i agree with ryan. but if yu cant get parts i might have a used one.
or buy a new compressor,

Metabo HPT EC99SM 4 Gallon Portable Electric Twin Stack Air Compressor, A-Grade Reconditioned

The EC99SM twin stack compressor features an oil-lubricated cast iron pump and 15 Amp direct-drive induction motor for long life. The motor is protected by a thermal overload protection that stops the motor in a possible overheating situation. Weighing just 52.9 lbs., the EC99SM also comes with...

toolsteal.com

Thanks Larry. I'll let you know if I can't find the part.

I checked - readily available, about #30. Will order tomorrow!


Thanks everybody!!!

 

[Chuck Ellis]

My answer will be of no help, but I have a 6 gal from California Air tools... it would pump up and shut off, then a few minutes later would run again... found that I had a bad weld job on the tank where the handle fit to move the compressor around... about a quarter tube of JB Weld fixed the weld problem and it's worked flawlessly since.

 

[Charles Lent]

The fitting in the tank where the air coming from the compressor has a check valve in it, and this check valve is bad. It may just be something caught in it, or it bay be defective.

Remove the line between the compressor and tank. Then remove the fitting where this line enters the tank.
Try to clean out the check valve part of it, but replacement of it will likely be necessary.

Charley

 

[Rennie Heuer]

The fitting in the tank where the air coming from the compressor has a check valve in it, and this check valve is bad. It may just be something caught in it, or it bay be defective.

Remove the line between the compressor and tank. Then remove the fitting where this line enters the tank.
Try to clean out the check valve part of it, but replacement of it will likely be necessary.

Charley

Yep - already ordered the part. Thanks Charles!