Question about Campbell Hausfeld Air Tools & Compressors

1 Answer

The unloader valve on the WL504100AJ leaks air when pumping and after shutoff. Is there a way to replace just the valve or is the only solution to replace the entire regulator module.

Posted by on

  • kdsix_dvp Jan 03, 2011

    I may have misidentified the valve as the unloader valve. The air leak is inside the regulator module not at the other end of the black tube which connects to the pipe coming out of the lower tank. I've had the cover off the regulator and have lubricated the valve - to no avail. Does this help?

  • kdsix_dvp Jan 04, 2011

    I disassembled the tank end of the air pipe and removed the check valve. Parts of the valve were badly corroded and the spring inside was broken. This definitely needs to be replace.
    Thanks for your help.



1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Campbell Hau... Master
  • 885 Answers

If you are leaking air at the unloader valve, even after the pump shuts off, your problem is the check valve. It's on the tank at the other end of the unloader tube, where the tube from the pump goes into the tank. I can't find a Campbell Hausfeld model #WL504100AJ so I can't tell you which check valve you need. The closest model numbers to yours are WL504311 and WL504312, and both of these use check valve #CV308300AJ.

Posted on Jan 03, 2011


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

3 Answers

Is the reed valve part of the pressure switch

relief valve should only open in a over pressure condition. If it is opening prior to reaching pressure ....replace it.

May 21, 2012 | Air Tools & Compressors

1 Answer

My M-1820 air compressor is blowing all the pressure out of the pressure release on the centrifugal unloader when it builds max PSI. When the pump is running there is no leaks but when it stops pumping it...

Without knowing what make compressor you have;
- if it leaks air while the pump is running, replace the unloader valve
- if it leaks air after the pump shuts off, replace the tank check valve

Mar 13, 2012 | Air Tools & Compressors

1 Answer

Air runs out of compressor

There is a check valve installed between the pump and the tank that keeps the air from leaking back to compressor pump and unloader (unloader is usually incorporated within the pressrure switch). Before replacing the checkvalve, make sure no other leaks using soapy water on all fittings including the drain valve.

Nov 20, 2011 | Air Tools & Compressors

1 Answer

Starts a little slow but does run up to pressure. , but will not restart when the pressure drops to the point where it should s5tart. It just hummmmmmmmm's. Any Ideas or do I need a new one?

This problem usually occurs when the in-tank check valve is leaking air back to the pump and the unloader is not working properly. Follow air discharge line from the compressor to the tank. This line is attached to the check valve (usually brass or chrome). A second smaller line also attaches to the checkvalve and leads to the pressure switch (unloader valve). After filling and shut off, you should hear a discharge of air at the pressure switch. If not, examine valve for possible mis-alignment with contact arm. If air continues to leak from the unloader valve, then checkvalve is leaking. Use universal replacement check valve if possible, check thread size. Parts are on ebay or Good luck

Apr 08, 2011 | Campbell Hausfeld 04 Gallon Twin Stack...

1 Answer

Blows breaker on start up after rest

There should be a valve on the switch or on the compressor pump itself that opens when the motor stops and relieves the pressure between the tank and compressor, it's call the unloader valve. If this isn't opening the motor will draw much more amperage than it should to start the compressor and it may not even be able to start it at all.

When the compressor reaches the shutoff pressure (or you turn it off) it should go "PSSssss..). If it doesn't then the unloader valve isn't working. If it's in the cold, the unloader valve may just be iced up- warm it up with a hair dryer and see if it'll work properly.


Dec 29, 2010 | Ingersoll Rand - Rand Type - 30...

1 Answer

Sanborn 15 Gal. Air compressor "bleeder-valve" will not shut off when compressor shuts down. I replaced with a entire new unit ( which includes this bleeder valve ) and it does the SAME THING...

Leaking bleeder valve /unloader is caused by faulty check valve. Follow the air discharge hose from the pump head to the brass valve at the tank. The brass valve is the check valve designed to keep pressure in the tank and prevent air from loading the pump when the compressor is trying to start. Remove the discharge air tube at the check valve and test for leak. If leaking replace with generic valve available at or on ebay. Good holidays

Dec 17, 2010 | Air Tools & Compressors

1 Answer

I have an 80 gal Craftsman air compressor who just shut down, the pressure is dropping, it made a smoke smell and it blew my circuit breaker. I tried starting my circuit breaker but it kept flipping off....

Usually related to the in-tank check valve. Follow the discharge hose from the pump to the tank. At the tank the hose attaches to a brass valve (or metal valve). This brass fitting is the check valve. It's purpose is to hold air in the tank and not allow the air to load the compressor when motor is trying to start. Easy to test. Use another compressor to pump air into your tank thru the quick disconnect or remove the safety valve and install hose there. Pump in about 75 psi and looks for leaks with soapy water. Remove air inlet hose from check valve and check for air leaks. If leaking, replace with generic valve available at or order from sears parts. If no leaks then suspect unloader is not working at the pressure switch. If both the unloader and check valve is ok then test capacitor for reading within 95% of rated valve. Good holidays

Dec 14, 2010 | Craftsman Air Tools & Compressors

1 Answer

Compressor wont restart because of head pressure

Piston air compressors have to unload to permit a restart, the two mot common types are an unloader valve or free air unloaders.

with an unloader valve this system uses a check valve mounted in the discharge line as it enters the tank, when the pump stops this check closes and does not permit the tank pressure to return to the pump. a unloader valve also opens to allow air pressure in the discharge line to vent, this valve is either on the pressure switch or on some models is on the pump, and is a centrifugal type.

Free air unloaders or head unloaders are a set of fingers that hold open the intake valves on the cylinders to permit the piston not to pump air against a head load, and once the pump is running the fingers retract to allow the pump to function as normal.

Jan 19, 2010 | Air Tools & Compressors

1 Answer

No air storage in the tank

so in another word your air compressor is mot pumping air.
(1) check for leaks
(2)check the air filter
(3) check the inlet valve
(4) if their is unloader valve (a) pressure switch
(b) load solenoid valve
(c) unloader valve

Sep 29, 2009 | Air Tools & Compressors

1 Answer

Unloader valve leaks on my compressor leaks air constant and I think that it must need replacing, does it? just old or what?


Mar 08, 2009 | Campbell Hausfeld Single Stage Air...

Not finding what you are looking for?
Air Tools & Compressors Logo

Related Topics:

375 people viewed this question

Ask a Question

Usually answered in minutes!

Top Campbell Hausfeld Air Tools & Compressors Experts

John Trevino

Level 3 Expert

1383 Answers

Joe Garcia
Joe Garcia

Level 2 Expert

205 Answers

Doctor PC
Doctor PC

Level 3 Expert

7733 Answers

Are you a Campbell Hausfeld Air Tool and Compressor Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides