Compressor Pressure
       Problem?

With so many questions and responses about why an air compressor does not build pressure, I am adding a number of pages of information to address this issue. This is another in this series of information pages.

Here is where you can post question of your own, or offer advice or a comment.

All new postings will be live on the forum for about a week to allow the original poster and others to comment. After that, if the content is relevant to the many visitors to this web site, I will make that post permanent, and move it to the appropriate page.

Thanks,

Bill

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Resources:

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Montgomery Ward compressor won't pressurize
       - tank "check valve" issue?

By: James, San Jose, CA

Question: My compressor is a Montgomery Wards brand 220v/1.5 hp 20 gallon model, with a Franklin Electric motor, a two-cylinder compressor, and a Kargard Industries tank. The date code on both the tank and the motor are 1972.

It seems my compressor has the same symptoms as the previous poster - it will not pressurize the tank above ~40 PSI. When the compressor is first turned on with the tank unpressurized, I can feel the cylinders sucking in air as they should; but as the pressure builds, more and more air is pushed right back out the intake valve. As with the previous poster, I disassembled the heads on my compressor to check the valves. They're just flat reed valves, and appeared to be in fine condition, just a little dirty. I cleaned the valves, head, and ports copiously, replaced the gaskets with new ones, and reassembled. But this did not solve the problem. Neither does changing or even removing the air filter.

Bill, you mentioned something about a "check valve going into the tank" in regards to the previous poster's problem. While his problem turned out to be a head gasket issue, it doesn't appear that mine is, so I would like to know more about this check valve. What is its purpose, where exactly is it located, and how do I test it? Thanks for the help! -James

Response: Hello James. Thanks for visiting, writing in, and including a photo. It sometimes makes answering so much easier.

If you look at your photo, see where the air line from the piston head turns and runs down to the tank on the left? Usually, the device that connects that air line to the tank opening is a check valve. It's purpose is to keep the air in the tank as the piston compresses it. The higher pressure air flows down the line, through the check valve, and into the tank.

If this check valve isn't seating properly, or has failed completely, then air can't stay in the tank as it's higher pressure in the tank than the line is when the piston is in the "suction" cycle. This may be an issue for you. Best to make sure the tank is empty, compressor is unplugged, and the disassemble the fittings at the tank, and examine the check valve. It should seal the air in one direction. Reassemble after cleaning (if needed) and see if this makes any difference, OK?

Comments:

Jan 09, 2012 Looks like a Champion pump by: Smithereens

Sorry to barge in here, but I saw a lot of posters asking about the pump on the Ward's unit. That looks to me like a Champion pump, and parts are still available for those. They were used on a variety of brands (Speed Aire, for instance), and they made a million of them, much like the cast iron Campbell Hausfelds. Check with Grainger or Champion - I think you will find the parts. - Mark

Oct 30, 2011 my 1972 speedair compressor,like pictured by: john mc gonagle

Hi Bill, my compressor looks just like the 1972 Wards,picture you have. Mine says made by Kargard industries. My problem is that one piston blows air outward,but the other one works normally. What is wrong?,where do I get parts,and how do I fix it? Thank you, Bill,it sure is nice to see somone who knows these things. John Mc Gonagle

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John, I am not sure what you mean by blowing air outward. Are you saying that the intake port is blowing air out instead of pulling it in? If so, that's a valve problem. Good luck on getting parts.

Aug 01, 2011 - I have a 1974 wards compressor - by: ron

Where are we getting parts for these compessors?

Apr 08, 2011 Same Pump, Different Tank by: jwellison67 at yahoo.com

I have an identical pump to the one pictured, that was found in an old building that we won at an auction, but it's on a much smaller (portable) tank and runs on 110V. My problem is that one of the pistons has been removed, and it is missing the rings. Everything else is there... except the rings. Does anyone have any ideas on where to find a set that fits?

May 20, 2010 Similar air compressor - by: Anonymous

I have an air compressor that is a 1974 that appears to have the same pump that yours has. However it has a newer motor on it. I was wondering if you could tell me the pump rpm's or the pulley sizes and the motor rpm's. Also I didn't know if there was any information on the pump itself. Any information you could give me would be great.

May 07, 2010 - added info check valve - by: Larry NM

If I am not mistaken that is a check/unloading valve. I have the next smaller version of that compressor shown in the picture. The unloading part quit working and I had it worked on. He installed a check valve and the compressor wont start under pressure. I am trying to order one at this time.

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Compressor will not stop running?

By: daniel, dc

Question:air compressor will not stop running???

Response: Hi Daniel. That your air compressor won't stop running can be pretty scary. What I don't know from your post is what's happening when the compressor keeps running? Does the pressure keep going up, pressure has stopped rising at a certain level, pressure isn't building at all. A bit more info, posted here so I can further respond, would be helpful.

Comments: Apr 08, 2012 - Compressor won't stop running - by: Mike

It will stop building pressure at what ever I set the little pressure release valve to, but the motor doesn't kick down like it used to when it reaches desired lbs.

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Mike, same response as given to Daniel. I don't know what you mean by "what ever I set the little pressure release valve to". Are you speaking of the PRV, or are you talking about the regulator? Typically, when a compressor doesn't stop running, the air pressure continues going up until the PRV lets go. Is this happening with your compressor, or, is the compressor running and running bot not building pressure past a certain point? Bill

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Another Compressor will not build pressure?

By: Mark, McComb, OH

Question:I think the reed valve is not sealing, but it looks okay. Everything in the head looks clean and in good shape. The piston has good suction. What can I do to repair it if it all looks good?

Response: Howdy Mark. When the compressor is running, is there a puffing or a pulse of air out the intake valve? You might pull the intake filter and carefully place your finger near the intake port to feel if there is pressure. If no air is coming out, then logically the only place the compressed air can go is into the tank. Now, assuming that there is no mechanical issue with your compressor, then why isn't the pressure rising? Well, if you have a gasket failure inside the compressor head, then the air is simply moving back and forth inside, and not getting pushed into the tank at all.

Comments: Jun 07, 2010 - Found the problem - by: Mark

When I posted my original question, I thought that everything in the head looked good but I did not realize that there was another gasket and spacer still stuck to the head when I removed it. I removed the spacer and gasket and found that the gasket was blown out between the intake and exhaust ports. I made a gasket from cheap gasket material and it has been working good for over a month.

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Glad to hear it's OK now Mark. Thanks for the update.

Compressor will not build pressure?

By: herbert smith, roebuck, sc 29376

Question:Blows air out the fider on top of compressor and with not build pressure above 50 psi.

Response: Howdy Herbert. Sorry mate, I don't know what a "fider" on the top of the compressor is? If it is, perhaps, the intake port, and you have air coming out that, it would suggest to me that your intake valve has failed, and your compressor is pulling air in, and then some of it is blowing back out the intake port, and not into the tank. At 50 PSI, the intake and out-blow is almost equal, and the pressure won't get any higher. Just my thoughts... and, by the way, what the heck is a "fider"?

Comments: Apr 19, 2011 - air blowing out valve at the top of compressor... Will not build pressure beyond 40 psi - by: Darius

My compressor is doing the same thing. He called it a "fider" but it is some kind of brass valve at the top of the compressor. The air is getting sucked in through the air intake part of the compressor on the side & it is getting blown back out of the brass valve on top around 40-50 psi. What could be the problem here?

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It would help if we all knew what kind of compressor we are talking about. If it is a two cylinder compressor, the valve you speak of may be the PRV, and if air is blowing out of that at 50 PSI, then either there is back pressure blowing it open (an intake valve failing on the second cylinder) or the PRV itself is th problem.