Compressor issue - follow up

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Forum topic by Robert posted 10-13-2019 05:46 PM 282 views 0 times favorited 4 replies Add to Favorites Watch
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3558 posts in 2025 days

10-13-2019 05:46 PM

While back I posted about my compressor making an awful noise and smoking.

Fast forward, I purchased a new compressor unit and when I installed it, now it appears the regulator is bad.

It will come to pressure but I noticed right away the distinctive brief air exhaust sound does not happen when it shuts off. It also erratically started the pump even though pressure was met.

So I’ve ordered a new regulator. I’m keeping the new compressor pump I figure what happens was the regulator wasn’t shutting it down and the pump overheated.

I guess what I’m asking is where does the air release that occurs when the compressor stops come from?

I checked the small release valve at the end it’s the regulator pressure tube it seems ok, I also checked the pressure tube itself it was not blocked or occluded.

Thanks guys.

BTW it’s a 5HP single stage compressor even at $490 For the pump it’s cheaper to fix.

-- Everything is a prototype thats why its one of a kind!!

4 replies so far

View HerringImpaired's profile


26 posts in 253 days

#1 posted 10-13-2019 09:13 PM

Is it the Unloader valve? It’s used to take the pressure off between the compressor and tank so the compressor can startup again without the pressure already on it.
I had to replace this on an old air compressor I used to own. The compressor would not start because it was already pressurized, and the motor would spin on the belt making the blue smoke leak out….
A trip to a local air compressor shop and a new unloader was procured and installed. Problem solved.

-- "My greatest fear is that upon my demise, my wife will sell my tools for what I said I paid for them."

View Robert's profile


3558 posts in 2025 days

#2 posted 10-14-2019 12:46 PM

Yes that sure sounds like it. But in my case the compressor still runs the smoke I saw I assume was from the compressor overheating and building back pressure forcing oil out the breather.

Regulator will be here tomorrow hopefully the issue will be solved.

-- Everything is a prototype thats why its one of a kind!!

View ibewjon's profile


1040 posts in 3338 days

#3 posted 10-14-2019 01:43 PM

The pressure unloader is part of the pressure switch on my compressor. I thought it was sticking open on mine, but I found the check valve was allowing air to flow through the unloader. ( Not your problem). Turn off power and look inside of switch. It is a needle valve that closes as the pressure between the check valve and cylinder bleeds off. It may be dirty.

View Robert's profile


3558 posts in 2025 days

#4 posted 10-14-2019 07:40 PM

I didn’t know they could be repaired so I’ve already ordered a new regulator, oh well.

My next question is if the unit was running for a while (maybe up to a couple hours) is it likely the pump is damaged? I found it running making a very loud dieselling type noise and the shop was full of blue smoke. Pump was extremely hot when I shut it down. looked like about 1/2 the oil was gone.

the next day I topped up the oil & switched back it cycled ok once, but then the unloader valve malfunction happened (which I was unaware of at the time) I mediately shut unit down,
Thanks guys!

-- Everything is a prototype thats why its one of a kind!!

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