Compressor won't build pressure past 50 PSI.

[Sonar Chief]

Need some help w my oil less compressor , I replaced both pistons, rings(seals), gaskets and o-rings and on start up it won't build pressure past 50 PSI.

I left a comment on the Sears tech blog ... no one has replied, anyone have a solution to this? I was wondering if the pressure switch is faulty, but how do you test the switch?

Any suggestions would be appreciated!

Michael

[samckitt]

I had one that did similar, It was the reed valves, one was broke off, so air was being pushed back out of the cylinder into the atmosphere, not in the tank.



http://i.ytimg.com/vi/9tbJ6Xo26v8/maxresdefault.jpg

Pic may not be exact one, but shows 6 little reed valves. Air is sucked in past them, but when compressed it seals & blows through a single valve.

Other side looks like:
http://ecx.images-amazon.com/images/I/51BAR5hgAUL._SX466_.jpg

[GregWeld]

SAMCKITT --- but then you're compressor ran non-stop but didn't make pressure --- Not sure if Michael is having that same issue or not.....


So Michael --- it it builds to 50 psi and shuts off -- sounds like either your motor is overheating and you're getting a thermal shut off --- OR your pressure regulator is acting up. I don't know how you'd test that.

[samckitt]

SAMCKITT --- but then you're compressor ran non-stop but didn't make pressure --- Not sure if Michael is having that same issue or not.....


So Michael --- it it builds to 50 psi and shuts off -- sounds like either your motor is overheating and you're getting a thermal shut off --- OR your pressure regulator is acting up. I don't know how you'd test that.

Yes, ran non stop.

[Sonar Chief]

I had one that did similar, It was the reed valves, one was broke off, so air was being pushed back out of the cylinder into the atmosphere, not in the tank.

I inspected the reeds and clean what little dirt was on them and re installed, here are a couple pixs with the heads off and new gaskets and o-rings installed.
http://imagizer.imageshack.us/v2/1024x768q90/901/pX4TpG.jpg
http://imagizer.imageshack.us/v2/1024x768q90/913/WYXEVb.jpg
http://imagizer.imageshack.us/v2/1024x768q90/633/btSDUg.jpg

Pic may not be exact one, but shows 6 little reed valves. Air is sucked in past them, but when compressed it seals & blows through a single valve.

Other side looks like:
http://ecx.images-amazon.com/images/I/51BAR5hgAUL._SX466_.jpg[/QUOTE]

SAMCKITT --- but then you're compressor ran non-stop but didn't make pressure --- Not sure if Michael is having that same issue or not.....


So Michael --- it it builds to 50 psi and shuts off -- sounds like either your motor is overheating and you're getting a thermal shut off --- OR your pressure regulator is acting up. I don't know how you'd test that.

Yes, ran non stop.


My compressor also runs non stop ... just makes 50 psi and no more! There is air being sucked into the intake, ie. no blow by or restriction.

Greg .... how do I tackle this problem? Can the shut off switch be bad if the motor continues to run, don't make no sense!

Thanks for helping .... I need my compressor up and running!

Michael

[samckitt]

If air pressure only builds to 50 psi, & motor runs on & on, then air has to be escaping somewhere. Now that I think about it, I also had to replace the one way valve on the tank where tube from compressor enters tank. Maybe that is bad. Let it run until you get 50 PSI & shut it off & listen for air leak.

[Sonar Chief]

If air pressure only builds to 50 psi, & motor runs on & on, then air has to be escaping somewhere. Now that I think about it, I also had to replace the one way valve on the tank where tube from compressor enters tank. Maybe that is bad. Let it run until you get 50 PSI & shut it off & listen for air leak.

A check valve? If that's bad wouldn't the compressor shut down, or no?

There is no sound of air leaking after I shut it down, Huh .... is there a universal part? Guess I could remove it and test it first ... then look for a replacement.

Thanks again for chiming in ....

[GregWeld]

I really have no idea where to go from here... it doesn't make sense that the compressor would "run on" - yet only make 50 psi - if the regulator was bad. To me that would allow the compressor to run on and NOT shut off... or wouldn't let it start.... but if the compressor is making "only" 50 psi - and continues to run without building pressure.... something else must be going on. What that is - I have no idea.

[Sonar Chief]

At first I did the dummy check ... is it really only 50 psi? I use the air hose and point it at your face :lol: ... yep 50 psi! Regulator checks sat!

I went ahead and ordered a check valve for the input port just in case, but the way I understand it ... if the check valve was inoperable it would direct the pressure to the relief switch and it would shut down, right??

There is no air that I can feel coming outa the port either .... the saga continues.

Thanks for commenting Greg...

[samckitt]

When my check valve went out it let compressed air out to the atmosphere. You could hear it.

[GregWeld]

Michael ---- GO here and poke around.....



http://www.about-air-compressors.com/after-rebuild-craftsman-919167783-wont-build-pressure-past-30psi.html

[GregWeld]

Same website - has a check list of things to consider and look for.... seems your issue is very common.


http://www.about-air-compressors.com/compressor-why-not-build-pressure.html

[Sonar Chief]

Same website - has a check list of things to consider and look for.... seems your issue is very common.


http://www.about-air-compressors.com/compressor-why-not-build-pressure.html

Thanks for the link ... at least I wasn't holding my breath for an answer from Sears!

Thanks again .... reading time now!

[Sonar Chief]

Well, this is frustrating as hell! After I replaced the pistons and cylinders, new gasket it would make about 35psi. Hmmm... bought the plates or "heads" which contain the intake and exhaust reeds, replaced them and the gauge, still running forever and never gets past 35psi, what the halibut?

Forums and emails have not helped much as I have replaced everything mechanical, the electric motor is not running hot (as it would if it lost one 120 vac line) ... so?

If anyone needs a 275 paper weight let me know! jk

I still need to get this fixed so I can keep using my air tools!

Any other suggestions?

Thanks again,

Michael

[dhutton]

Well, this is frustrating as hell! After I replaced the pistons and cylinders, new gasket it would make about 35psi. Hmmm... bought the plates or "heads" which contain the intake and exhaust reeds, replaced them and the gauge, still running forever and never gets past 35psi, what the halibut?

Forums and emails have not helped much as I have replaced everything mechanical, the electric motor is not running hot (as it would if it lost one 120 vac line) ... so?

If anyone needs a 275 paper weight let me know! jk

I still need to get this fixed so I can keep using my air tools!

Any other suggestions?

Thanks again,

Michael

Is the unloader valve stuck partly open?

Don

[dhutton]

Unloader valve information here:

http://fix-my-compressor.com/air-continuously-leaks-out-of-the-unloader-valve/

Don

[Sonar Chief]

Is the unloader valve stuck partly open?

Don

I don't believe so ... the tank is holding pressure! It makes so much noise when its running, I can't hear any leaks though.

I even replaced the check valve, there was nothing wrong with the OEM thou!

Got me ....

[dhutton]

The unloader valve is a different valve than the check valve. It releases the compressed air from the cylinders when the compressor powers down so that it does not have to start back up under load. It will cause the problem you are having if it is leaking and bypasses air all the time.

At least this is my understanding.

Don

[Sonar Chief]

The unloader valve is a different valve than the check valve. It releases the compressed air from the cylinders when the compressor powers down so that it does not have to start back up under load. It will cause the problem you are having if it is leaking and bypasses air all the time.

At least this is my understanding.

Don

Don ... I pulled the unloader valve from the switch and blew it out, started the compressor and put up a cardboard shield and there is no leak!

I then pulled the intake line off the top of the check valve and started it .... yep compressed air going into the tank!

This makes no sense .... won't get past 35psi no matter how long it runs!

Thanks for commenting .....

Michael

[Build-It-Break-it]

Silly question but have you tried another gauge? Could the gauge be reading wrong? They go bad all the time.

[Sonar Chief]

Silly question but have you tried another gauge? Could the gauge be reading wrong? They go bad all the time.

Yes ... I installed a new gauge, still reads 35psi ... I did the ol test the air pressure by pointing the air at your face and ... yep 35psi. lol

[GregWeld]

...... and..... ever figure this out??? I think we're all stumped.

[Sonar Chief]

...... and..... ever figure this out??? I think we're all stumped.

Greg ... never figured this out! :shakehead: I have it on CL for sale as NON-OP, I ordered a Quincy 5hp 60gal to replace this oil less compressor, if it doesn't sell I'll plumb it for extra volume!

[dhutton]

Greg ... never figured this out! :shakehead: I have it on CL for sale as NON-OP, I ordered a Quincy 5hp 60gal to replace this oil less compressor, if it doesn't sell I'll plumb it for extra volume!

The only other thing that comes to mind is maybe the cylinder bores are out of round. Didn't realize it was oil less. They are not known for longevity.

Don

[Che70velle]

Greg ... never figured this out! :shakehead: I have it on CL for sale as NON-OP, I ordered a Quincy 5hp 60gal to replace this oil less compressor, if it doesn't sell I'll plumb it for extra volume!

Do not plumb your existing unit into your new one. The 5hp unit you have coming will be severely overworked, as it is not designed to pressurize more tank volume than what it has under it. I tried this. I was warned to not do it, as it would overwork my compressor, and sure enough, my 5 horse compressor is just about done, after working so much harder for a couple years now. Yes I have more air volume, but I have a compressor that runs twice as much as it used to, also.

If the compressor doesn't sell, give it away. Just don't tie it into another one, unless the motor and compressor unit on it is very overrated.
Personally, I have firearms. Lots of firearms, and ammo. I would use your non working unit as a target. That would be a fun day.

[Sonar Chief]

Do not plumb your existing unit into your new one. The 5hp unit you have coming will be severely overworked, as it is not designed to pressurize more tank volume than what it has under it. I tried this. I was warned to not do it, as it would overwork my compressor, and sure enough, my 5 horse compressor is just about done, after working so much harder for a couple years now. Yes I have more air volume, but I have a compressor that runs twice as much as it used to, also.

If the compressor doesn't sell, give it away. Just don't tie it into another one, unless the motor and compressor unit on it is very overrated.
Personally, I have firearms. Lots of firearms, and ammo. I would use your non working unit as a target. That would be a fun day.

That's good to know! I have an offer on it already, so I'll just let it go!

Thanks,

Michael

[GregWeld]

Compressors are like understanding "Cams".....


Compressors do two things -- make pressure -- produce volume. The storage is just a buffer area.


The KEY to compressors is having one that will make enough Cubic Feet per Minute at the pressure you need to run the chosen tool.


Regardless of the storage size -- if the tool is using more CFM than the compressor can produce... the tool will strip the air from the buffer and the compressor will run non-stop trying to keep up.


They types of tools, and work, we do - pretty much means you need a compressor that will produce 90 PSI at about 17 CFM....

[Sonar Chief]

Compressors are like understanding "Cams".....


Compressors do two things -- make pressure -- produce volume. The storage is just a buffer area.


The KEY to compressors is having one that will make enough Cubic Feet per Minute at the pressure you need to run the chosen tool.


Regardless of the storage size -- if the tool is using more CFM than the compressor can produce... the tool will strip the air from the buffer and the compressor will run non-stop trying to keep up.


They types of tools, and work, we do - pretty much means you need a compressor that will produce 90 PSI at about 17 CFM....


Thanks Greg ... the new compressor comes in about 15.2 cfm, I thought about the next size up but wholy cow the price went up considerably. I'll make due w this one!!!

Should be here next week, which is also the last week of school for this session ... then it's MY TIME w the Camaro!

Michael

[GregWeld]

yeah -- 15+ CFM should be able to do some work without it just running and wearing itself out. Regardless of what you bought -- it's going to be way better than than so called "oilless" versions -- which are useless except to fill bicycle tires.

[Sonar Chief]

yeah -- 15+ CFM should be able to do some work without it just running and wearing itself out. Regardless of what you bought -- it's going to be way better than than so called "oilless" versions -- which are useless except to fill bicycle tires.

Ain't that the truth .... I inherited it after my brother passed, so the price was right! Didn't have any experience w the oil less pumps then ..... lessons learned, moving on!

Michael