Your Air Compressor's Not Building Pressure -- Could The Cause Be A Valve Plate Failure?

If your air compressor isn't building any pressure, a likely cause is that the valve plate is broken in some way. The valve plate controls the flow of air between the tank and the cylinder, and so a complete lack of any air likely points to a problem with the plate rather than a malfunction of the cylinder itself.

Replacing the plate isn't especially difficult. It's located right below the cylinder head, and to access you need to remove the cylinder from the tank. You'll need to order a new valve plate that fits your model of air compressor either directly from the manufacturer or from a store that carries compressor parts. You may not be able to find a valve plate for an older compressor on the shelf, and you may need to order one and be without the use of your compressor for a few days.

Once you have your new valve plate in hand, you can prepare your compressor for the replacement. Drain the air from the tank and then locate the tube that connects the cylinder and tank. You'll need a wrench to loosen the nut holding the copper tube. Once the tube has been disconnected from the cylinder, you're ready to go.

  1. Remove the cylinder head. Use a socket wrench to loosen the four bolts holding the cylinder head; the size of the bolt will vary depending on the model of air compressor you own. 
  2. Remove the metal valve plate that is directly between the cylinder head and the cylinder. The valve plate holds several reed valves, any of which may be missing an edge and thus allowing air to flow between the cylinder and tank. Your new valve plate will have complete reed valves that will block air flow as needed to build up the necessary pressure for the compressor to function.
  3. Install gaskets on the new valve plate. A new plate will need gaskets installed around the reed valves; these may come with your valve plate or you may need to purchase them separately. They're inexpensive enough to get new ones rather than try to reuse the ones on the existing valve plate.
  4. Position the new valve plate exactly as the old one was on top of the cylinder.
  5. Replace the cylinder head and align the bolt holes with the valve plate and cylinder. Reattach the bolts.

You'll then need to reinstall the copper feed tube that moves air from the cylinder to the tanks. Make sure the nut is fastened securely but don't overtighten it.

If you continue to have problems with air flow, contact a qualified repair shop for help in assessing the issue and replacing any worn or broken parts. Click here to learn more about air compressor repair