Air Coming Out the Intake Filter on Air Compressor? Here’s Why & How to Fix

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What does it mean when your air compressor has air coming out of the intake filter? This is often a symptom of an air compressor that will run, and run and the air pressure in the tank only rises a little bit. Because the air pressure in the tank cannot reach the pressure switch cut-out pressure level, it is possible that the air compressor will run to the point where it starts to self-destruct.

This page will provide you with why air comes out of your intake filter and how to fix this issue!

Air Compressor Intake Filter & Valves

To understand what is happening when the air compressor has air coming out of the intake filter, it helps to know how the valves on the air compressor work.

The valves vary depending on the manufacturer, of course. The smaller DIY type air compressors typically have a valve plate sandwiched between a couple of gaskets, a plate similar in concept to the drawing below.

Drawing of typical air compressor valve plate

In this drawing, we have removed the cylinder cap and the gasket to view the valve plate from the top. This arrangement is also commonly referred to as the head gasket and reed valves.

The LP – low-pressure valve controls the air intake into the cylinder head, entering the pump through the intake filter. The HP  – high-pressure valve controls the flow of air from the cylinder head into the line heading down to the tank.

As the air cylinder piston reciprocates, it alternately opens and closes the two valves on the valve plate, depending on if the piston is rising and compressing air, or dropping, which pulls closed the HP valve and opens the LP intake valve at the same time. The piston cycling up and down is very fast, and these two valves are put under a lot of stress as they are pulled or blown open each time the piston cycles. The throw of the valves is not large, but the speed with which they move is impressive, leading ultimately to metal fatigue and the valve cracking or breaking right off.

Why Air is Coming Out of Intake Filter

When you have air coming out of the intake filter, it is is a sign that the LP, the low-pressure valve, is failing or has failed.

Just like a piece of wire that you bend very quickly in your hands, the metal in these valves gets very hot. That heat, coupled with the high cycle rate, particularly if the materials used in the valve construction are poor quality (like those typically found in a cheap air compressor) contributes to metal fatigue and valve failure.

How to Fix Air Coming Out of Intake Filter

Really, you have only one choice when the compressor symptom is air coming out the intake filter. You need to replace the valve plate.

Of course, that’s where the fun begins. If air is coming out of your air intake filter, you will need to remove the covers of the motor to access the compressor pump head. Then, you will need to remove the four bolts on top of the pump to remove the head and the valve plate.

The valve plate, or head gasket, should have two thin metal plates that act as the valves (commonly referred to as reed valves), as shown in the diagram further up the page. If these parts are indeed broken, you will need to replace them.

Here’s an example of replacement reed valves available on Amazon for central pneumatic/harbor freight air compressors.

For Central Pneumatic Harbor Freight Air...
86 Reviews
For Central Pneumatic Harbor Freight Air...
  • These are the reed valves as found in fits Central Pneumatic Harbor Freight air compressors as well...
  • They measure approximately 3/8" x 1 3/4"
  • You will receive (2) reed valves with your purchase.

Last update on 2024-07-11 at 05:08 / Affiliate links / Images from Amazon Product Advertising API

If you’re replacing the reed valves, you may as well replace the gasket at the same time. It’s possible to buy a head gasket and reed valve replacement kits together in a set.

It may be possible to get a technician from your compressor’s manufacturer to come to you and fix this air coming out of the intake filter at your home. This leads us to the topic of your compressor warranty.

Below, I’ve picked out a useful YouTube demonstration on fixing the reed valves, potentially saving you money if you have the basic tools at hand!

Compressor Warranty

If the air compressor you are having this problem with was purchased from a big box store, and the air compressor is under warranty, it will be up to the store policy to either repair or replace the air compressor. Take it back – along with your original sales receipt – and request a new one.

Odds are good that the big box store hasn’t got a lot of interest in trying to get your compressor fixed, as the net cost to them for a new one is likely less than the labor and repair costs of fixing an old one. They may just take the damaged air compressor back, give you a new one, and toss the old one into the garbage hopper.

The odds are very good that the store where you bought the air compressor will not stock parts of this type for it. If the store does send out air compressors for repair, contact that repair company for assistance in getting parts.

If the air compressor is the store’s house brand, somewhere in the bureaucracy that is the supply chain of the big box stores someone should be able to tell you the source of the air compressor that you bought in a specific year. Even though the brand of the air compressor may not have changed, it is quite possible that a specific brand of store air compressor has been made by different compressor manufacturers over the years. It will be a giant pain in the backside to do, but you will have to find out who made the compressor and contact that manufacturer directly.

Unfortunately, if the compressor manufacturer is offshore, and they do not have a sales or distribution organization here, then good luck. Getting OEM parts may be impossible.

Online sourcing can help. Companies that supply parts to rebuild or repair the smaller, DIY type air compressor, and there are a lot of them now, can sometimes get you parts. Just like the part that is readily available on Amazon I provided up the page, there are many more out there, you just need to conduct sufficient search and find the right one for your compressor.

In all of this process, keep in mind the cost of repair in terms of time to source, money to buy the parts if you can find them, time to dismantle and rebuild the compressor, and total that up.

Compare that to the price of the compressor when you bought it, and compare that total to the cost of a new compressor today.

You may find that fixing the problem of air coming out of the intake filter isn’t worth the effort or the money.

FAQs (Frequently Asked Questions)

What does air coming out of the intake air filter indicate?

When air comes out of the intake air filter it is likely that the valve plate is broken. The valve plate should normally keep air coming out of the intake so that the piston is able to force air into the tank. To inspect this, you will need to remove the covers on the motor to gain access to the pump head.

Why does my air compressor keep releasing air?

This could be down to a number of reasons, and it depends on where the air is being released. In some cases, the tank may be over-pressurized, and so, the pressure switch isn’t shutting off the motor when the air tank reaches its cut-out pressure. If air is continuously leaking from the unloader valve, then it may be that your compressor check valve has completely failed or is faulty. Another possibility is a broken valve plate, which is resulting in the air coming out of the intake rather than forcing the air towards the tank.

How do you know if your air compressor valve is bad?

There are a few indications to look out for that may mean that you have a faulty air compressor valve. These include a higher than normal suction pressure, a low discharge pressure, the compressor being very quiet, low amp draw, an unusually high discharge temperature, contamination of the valve plate, an overloaded or overheated compressor, and cut-in and cut-out pressure being too close together.

How does an air compressor inlet valve work?

By Ashley Pearce

As a passionate manufacturing and mechanical engineer, I've had my fair share of run ins with air compressors and compressed air systems. With over a decade of experience in the industry, I have both a fresh perspective and time-served hands and mind to help you with your compressor problems (along with our able community!)

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February 13, 2021 9:03 am

I recently changed my valve plate with a new one and i still have air coming out of the intake, i’m able to build pressure in the tank, but issue still troubles me, any ideas what could be wrong? Model is a pafc5030 oil free compressor and i recently change the piston sleeve and piston ring plus the gaskets and valve plate…

Fix My Compressor Moderator
Fix My Compressor Moderator
Reply to  Feak1
February 13, 2021 10:34 am

Assuming there is no gasket damaged or missing between the valve plate and the intake, is it possible that the valve plate was installed upside down?

Reply to  Fix My Compressor Moderator
February 14, 2021 3:11 pm

Thanks for replying!!

Gasket are brand new and valve plate is sitting on the right side, i have double checked with the pump diagram and dissambled/reassembled There s no leak anywhere except out of the air filter. (Checked with a 3 foot long hose connected to intake)

The compressor works fine but i thought that fixing that issue rebuilding the pump with new parts would make it pump faster, but in the end i’ve rebuild the pump to get to the same results…

Fix My Compressor Moderator
Fix My Compressor Moderator
Reply to  Feak1
February 14, 2021 4:08 pm

I understand that rebuilding a failing pump/cylinder/piston will redress problems caused by wear. What were the circumstances that caused you to think that parts were worn?

The pafc5030 oil free compressor is of DeWalt make. Air would not normally be escaping out of the intake when new. If the new valve plate is in correctly, and if there are no compromised gaskets, and if the pump head is bolted securely making sure there isn’t a gasket air link between the pump cap and pump that you might interpret as an air leak through the intake filter, I can’t conceive of any reason why air should come out there.

Anyone else?

Reply to  Fix My Compressor Moderator
February 14, 2021 6:45 pm

I bought the compressor used and noticed that air was coming out on the intake side, so i purchased the necessary parts for rebuilding the pump but even with new parts the issue is still there. To make sure it was coming out from the intake and not anywhere else, i have mod the intake filter to attach a hose so that i could isolate the air coming out of it, so its no mistake , it really comes out from the intake 100% sure. Like i said the compressor works just fine, can’t really complaint, but this issue bugs me… I might just live with it lol

January 30, 2017 2:18 am

You can make them from a metal scaper. Its realy not that hard to take apart and then trace your bad one. Then just cut out the pattern and install. Gaskets usually stay good as long as you take your time pulling it apart. And not try an manhandle the head and gaskets lol

Mike R
Mike R
October 4, 2016 3:45 pm

This info was a great help,at least I now have a good idea what the problem is,not sure it will be easy to fix though. Thank You.