# Compressor diagnosis



## Polsom (Oct 12, 2020)

Hi all,

I've had this compressor for a few years but it's been sat to the side due to an issue that it developed over only a few years use.

It still runs fine, starts up and builds a bit of pressure but once it gets to about 50psi it just fails to gain any more pressure.

I did some reading and supposedly it's quite common for reed valves to wear out so I removed the 6 bolts at the head and took that off but that simply revealed 4 perfect condition reeds that showed no issues.

I've done a soapy water test and tightened a few leaks and added o-rings where I thought they were needed and this managed to get me a few more PSI but still far shy of the motor stopping, I think it's supposed to get over 100 PSI. I also replaced the seemingly unique tank mount reulgulator with a new one but again no difference.

I'm fairly sure this is just some cheap Chinese brand but it does work, and similar models of this size seem to run thousands of dollars which is why I sort of want to save it.

Is there anything else that I could look at before I should rule mechanical failure like piston blowby etc?


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## iowagold (Jan 22, 2020)

do the basics,
clean or replace the air filter, snap a pix of the piston.
clean the check valve, clean the unloader.
put a gauge on the tank as well as the one on the regulator.
clean the regulator or replace it.
clean or replace the tank max pressure pop off valve.


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## Polsom (Oct 12, 2020)

iowagold said:


> do the basics,
> clean or replace the air filter, snap a pix of the piston.
> clean the check valve, clean the unloader.
> put a gauge on the tank as well as the one on the regulator.
> ...


So there's 3 items there I can't identify, the check valve, the unloader and the pop off valve. Would it be possible to point them out in my photos?

I believe one of them is the brass fitting that the exit pipe from the top of the head goes into.

There is another gauge on the control box with the power switch which reads the same as the regulator - which I changed already.
Also removing the head assembly only revealed the reed plate I'm not sure how to get at the piston as there are no more fasteners on the reed plate.


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## iowagold (Jan 22, 2020)

snap some more pix.
i need pix of the switch area.

the check valve should be inline with the output from the compressor to the tank.
it might be the fitting at the tank.

have you drained the water out of the tank??

the unloader maybe part of the electric switch assy.
as well as the pop off valve may be at a 4 way fitting under the unloader. with the tank pressure guage.


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## Polsom (Oct 12, 2020)

Yes I can identify the check valve, the pipe between it and the the compressor has to be removed when the head comes off, I had to re-flare it at one stage as it stopped sealing however I've done soap tests on both ends as well as the check valve and no leaks. Unless the check valve isn't opening correctly and causing a restriction, I'm not sure how I would go about checking that.

Tanks been drained multiple times no water inside, as well as compressor being topped up for oil. Like I said appears to be in perfect working order.

Will try get a few more photos soon.


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## Polsom (Oct 12, 2020)

Hi again, sorry for the late reply grabbed a few more shots. One which I believe is the one way valve out of the compressor going into the tank, other is the switch block with the gauge. Under the black cover is an adjuster which I believe just sets the load cut off for the electric motor. Let me know if there's anything else I can check to diagnose. It looks like the smaller pipe from the one way valve feeds into the switch block, could this be a point of failure?


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