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Sears compressor motor running and belt squealing

Published Categorized as Air Compressor Making Noise, Sears No Comments on Sears compressor motor running and belt squealing

My sears compressor starts pumping fine until about 60psi and then the pump stops and the electric motor keeps running squealing the belt. when i shut it off and turn the pulley by hand the pump turns free and easy.


Mmmm, yes, that is odd.

As the pressure in the tank increases towards cut out pressure, the load (the work the pump and consequently the motor has to do to pump more air) increases.

So, it seems to me that as the load increases the harder work is stalling the pump.

It could be that the heat that is generated by the pumping process, causing something to bind in the pump, stopping the pump sheave, and forcing the belt to move through the sheave groove instead of rotating the sheave. This would create the squealing sound you hear.

You say that you remove the belt, and the pump sheave turns easily by hand, which seems to contradict what I’ve just said.

Unless, the time it takes you to disconnect the belt allows the unit to change (cool?) in some way that relieves the binding.

First thing though? Check the alignment between the two sheaves as well as the mount of the pump and motor to ensure that as the back pressure grows, that isn’t forcing them out of proper alignment?

Well, what did you find? Please leave a comment and tell us the model of the compressor, and upload a photo or two via the form below.

If you’re wondering how to size a motor pulley, we have a guide with a worked example on our site!

New comment? New question? Please add it here along with photos to help others help you with your compressor and equipment problem!

By Bill Wade

About Air Compressors has been helping folks with their Air Compressor Problems since 2002 online. We're a community of DIY and Compressed Air professionals who are keen to support everyone across the globe with their air compressor issues and troubleshooting. Whether you're trying to identify an old air compressor, or troubleshoot an error code on a sophisticated new industrial air compressor - the community at About-Air-Compressors.com is here to help you

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