How to overhaul an older compressor

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fix old compressor
(Last Updated On: August 31, 2020)

Question:

I have just been given a rarely used 15 year old air compressor from my father inlaw, he was a tradesman and it was a good tool.

old air compressor

It is now in need of some “TLC” an overhaul and I need some handy tips to do this, all the things I need to do to make it safe,  can you help?

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Answer:

A visual inspection, of course, to make sure that there’s nothing obvious, like a hole in the air tank.

Then an oil change if it’s an oil lubricated compressor.

Inspect further the power cord to make sure there’s not breaks or shorts, check to make sure the tank drain valve is closed, then fire it up.

overhaul old air compressor

If the tank is empty, as it should be, the compressor should start.

The first time you run it, monitor the air pressure in the tank as the compressor works. If the air pressure gets up to 150 PSI without the compressor shutting off, pull the plug.

Then, manually open the PRV valve, and let the compressor blow down. Push the PRV valve closed, and plug the compressor in again.

You’ve done that to try and make sure the PRV is able to release if the pressure in the tank reaches too high a level.

Monitor closely as the  pressure goes past 150 PSI in the tank. If the PRV doesn’t open and blow off the pressure as the tank pressure is exceeding 190 PSI, that may not mean that you’ve got a PRV problem. It may be that your compressor is good for higher pressures, but you’ll need to find out.

All things being equal, most DIY type air compressors will hit cut-uut pressure around 120-150 PSI and the compressor should shut off somewhere around there.

If that happens, away you go. Enjoy using your compressor. If it doesn’t, write back in.

Hello, I am Bill, the Compressed-Air-Man. I have years of experience in industrial and residential compressed air applications, air compressors and general pneumatics. I created this site to help professionals, students, and DIYers understand and properly implement and maintain compress3ed air systems.

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