21 gal won't go over 60psi?

need some troubleshooting tips to help fix the problem.

Assuming your compressor pump is working correctly, then the air that's being pumped by the air compressor is going somewhere?

One issue may be the intake valve leaks, with air being pulled in and then right back out the same intake port. Test that by pulling the intake filter and feeling the air flow at the intake port.

Another might be a gasket failure, a leaking check valve, or.... why not look on the Troubleshooting page for the link to the pages that discuss the various reasons why an air compressor will run, but the air pressure won't build past a certain point?

After you have checked a few things, if you are still stumped, post a comment here. Knowing a bit more about your Central Pneumatic air compressor such as model, age, use level and so on.



Comments for 21 gal won't go over 60psi?

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Apr 03, 2017
Won't go over 35 psi!
by: Bill

Possible pump issues.

See the troubleshooting pages on this site about why air compressors run and don't build pressure. Pretty much answers your question and provides guidance.

Apr 03, 2017
Pancake compressor won't go over 35 psi!
by: Anonymous

Bought it at Harbor Frieght a few years ago and it worked fine but then just kept running and won't reach 100 psi or stop. I've drained the condensation and tightened up all screws but still won't charge over 35 psi. I noticed the reset button does nothing as well so hope someone can help me figure it out.

Thank you

Nov 06, 2015
93271 Air Compressor 50 only 50 PSI
by: Mike

I took the cylinder head off and found the Gasket in the upper section (above brass plate) was blown in the interior section. Replaced gaskets and now works like a charm. Hope that helps someone.

Jul 27, 2013
central pnuematic air compressor model 95498
by: Fred 6/26/12

I had a bad leak on mine and it would not go past 50 psi. I dissconnected the copper tubing leading from the exhaust elbow to the check valve before it goes to the tank. I found a hair line crack in the elbow when i tried removing it the thing broke in pieces. I used a bolt extractor to remove the rest from the head. I then found thru amazon a 16.5mm male elbow (almico air compressor elbow $5 plus delivery) and reconnected the copper tubing. I found that i still had a leak in the tubing at the nut where it connects to the fitting. I found an rubber O ring and put it inside, tightened up the nut and now it builds up pressure no problem.
The only forseable problem is how hot the copper tubing gets and that the O ring will degrade.
The elbow was tough to find anywhere else. the stores had no idea its size or type.
Good fix. I agree about the "O" ring. I'd have gone with a copper ferrule compression fitting it were me. If the "O" ring melts, acquire one made of high heat plastic or high heat silicone.

Jun 17, 2011
#47065 won't continue to run
by: Tommy

Compressor runs and shuts off and you have to push the reset button and in alittle while it starts and runs again for a few moments and shuts off again. I pulled the cover off of the pressure relief valve and turned the bolt in the + direction and it still does the same thing but now will go to a higher pressure.


What you adjusted sounds like the pressure switch, not the pressure relief valve.

It sounds as though your air compressor is going off on thermal overload. Sounds like something is overheating the motor. Could be a mechanical issue back loading the motor shaft, could be the motor itself is failing, could be that you're using a too small extension cord or too many other items are pulling power from the compressor feed, and you are underpowering the motor, which causes an overheat.

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Shuts off at 40PSI?

Central Pneumatic 2HP 8 Gallon air compressor (photo: www.harborfreight.com)

Central Pneumatic 2HP 8 Gallon air compressor (photo: www.harborfreight.com)

I have the the Central Pneumatic 2hp 8gal compressor. I will turn it on and it will build pressure to 40psi and the circuit breaker on the side will trip and the compressor will shut off.

I can wait the 5 seconds and press the brass relief and it starts up and runs for about 3 seconds and shuts off again.

Out of the box it did run to 120 psi but now it only will run to 40psi HELP!
Friend, I have a bit of a problem understanding what you mean by "wait the 5 seconds and press the brass relief". What brass relief is that, please?

As a comment here, can you tell me more about this brass valve, and also please tell me the model number of the Central Pneumatic air compressor.

Also, do you have your air compressor plugged directly into a socket or if you are using an extension cord? If you are using a cord, try plugging the compressor directly into a wall socket. Motor overload and subsequent thermal valve popping can be cause by a motor being under powered.

If you want to do a bit of research yourself, visit the troubleshooting section on the sitemap page, and follow the links to the compressor will not start page for more tips.



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Central pneumatic compressor will not build above 25psi?

by jack

central pneumatic air compressor will not build above 25psi

central pneumatic 21 gal upright i have changed pressure valve add sealent to head of compressor still will not build air above 25 psi
Jack, when you read the reasons why air compressors don't build air pressure, on the page where you added your comment, which of the things listed did you have the chance to check?

I don't want to cover old ground.

Please add a comment here telling me which of the checks listed you did, and we'll see if can help each other figure out what's going on with your air compressor.

It would be good to know the model number, how old it is, and if it's been used a lot.

Can you provide more info, please?



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I made a reed valve for my Central Pneumatic compressor?

by David Curtis
(New Tazewell, Tn. USA)

My reed valve failed after 2 hours use. Is there a replacement part available? Harbor Freight says this model has been discontinued.
David, sorry chum. If HF cannot supply, then you have a problem. I'm posting your request in the hope that someone can direct you.

One contributor has made his own. See that post below for details.

Good luck.



Reed valve replacement / I made my own and it works!!!
by: scooter dave

I was able to replace the horse shoe shaped reed valve with a piece of .010 spring steel. Rough trimmed it with metal snips and finished it on the grinder, (sandwitched between two pieces of thin wood. Made a new gasket from rubber coated fabric. Works great.....115 PSI. We will see if this lasts longer than the original.


Good stuff, Dave. I made a small adjustment to your title to help other folks find your post.


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Jul 11, 2014
CP 94667 gasket kit
by: Todd

Bill, I appreciate you sharing your expertise on your website. My Central Pneumatic 21 Gallon 94667 would run continuously, but never build more than about 40 pounds of pressure. Based on info I found here, last night I repaired it by installing a gasket kit I found on ebay for about $21 including shipping. (I searched for "HL026100AV", as someone suggested on your site). It fit perfectly, including the new reed valve and pins, and the compressor now works as expected. Thanks again for sharing your valuable experience and advice!
You are most welcome, on behalf of me and the many contributors that were a help. Cheers,


Jun 18, 2013
Reed Valve
by: Bruce Bennett

Where would I get this Spring steel, and the gasket material you used ?

Jun 12, 2013
You got it right Bill
by: Scooter Dave

Bill, That is exactly why I sandwiched the metal between the wood. It is very thin and would distort while grinding. Good catch...I should have explained it better.

Jun 10, 2013
Reed Valve
by: Bruce Bennett

I read your comment about making your own gasket, but I am a little confused about your spring steel, and sandwiching it between 2 pcs, of thin wood. What kind of wood ? Then, the rubber coated fabric ?
I don't quite understand the reason for the wood.
Any info on making this easier to understand would be appreciated !
Hi Bruce... I read this to mean that since the .010 spring steel is so thin, in order to grind it to size, he used wood to hold the steel flat. I doubt the type of wood made any difference, it was just there to reinforce the steel so it could be ground.


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