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Compressor grinding after oil change?

manoweb

Well-known member
Joined
Oct 9, 2013
Messages
97
Location
California
I just drained the oil of my 60gal, "5HP" compressor; no big deal. As I had a half a can of unused compressor oil I wanted to get rid of, I used that to flush out a second time. I just noticed some pretty fine black particulate in the oil, but nothing out of the ordinary I think. I used a high quality synthetic oil as final replacement. I remember I checked the belt and it's in a good shape, I turned the flywheel by hand and everything looked and sounded good.

I removed the air filter, washed it, let it dry for several days while I was not using the compressor.

I realized that the ground connection on the electrical side wasn't good (crimp terminal too big for the ground wire gauge) and I fixed it.

I removed the little "muffler" on the second stage output (same two bolt pattern as the intake filter) because I was curious and then I reinstalled it. I opened the front plate that exposes the bearings, had a look out of curiosity and reinstalled it

I tilted down the compressor on its side for about 15 minutes to replace the drain plug with a high quality brass valve. Because of the angle a small quantity of oil spilled out of the top of the cap. Oil level was still well within the normal range in the sight glass.

Now, this is what happens:
https://photos.app.goo.gl/LUTUzmKgUvH2TrHC9

When I turn the compressor by hand, at some point (when you hear the vibrating noise in the video) I can *feel* like if it's grinding. Note, the belt cage vibrates and makes some noise, but the grinding really comes from within the pump.

Thing is, I did run the compressor for 5 seconds before realizing it was WAY too loud and I shut it off immediately. Even in only few short seconds, the compressor was able to build up some pressure in the tank, almost like if performance isn't affected.

Anybody has any idea what might have happened? Should I open up the head? I have not worked on a compressor before.
 
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DeeKay

Well-known member
Joined
Nov 25, 2020
Messages
448
Location
Colorado
Sounds like belt/belt guard noises to me too. and maybe some air whistling through the valves.

If you're really concerned then sure pull the head and have a look and maybe drain the oil again and see if there's any glitter in it.
 
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manoweb

Well-known member
Joined
Oct 9, 2013
Messages
97
Location
California
Upon further inspection, yes, it seems the guard is interfering with the flywheel, that would explain the excess noise. I will have to straighten out one of the mounts and try again... thank you so much for the support - also, it shows the decline of problem solving abilities at 2AM :D
 

David99

Well-known member
Joined
Oct 2, 2012
Messages
668
Location
Treasure Coast, Fl.
Upon further inspection, yes, it seems the guard is interfering with the flywheel, that would explain the excess noise. I will have to straighten out one of the mounts and try again... thank you so much for the support - also, it shows the decline of problem solving abilities at 2AM :D

Usually by that time I find some things more amusing:evil:
 
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