Air Compressor Puzzle


Old 08-03-05, 11:22 PM
DIYinOR's Avatar
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Air Compressor Puzzle

I recently acquired a Speedaire compressor model 3Z408E, it is gas powered (4Hp B&S) with a 2 stage cast iron pump and 10 gal horizontal tank. It "appears" in great condition and even came with all the manuals (always a plus). I am new to compressors and am enjoying the challenge of learning how things work or don't. Right now it don't, or doesn't, well it does then it don't or won't. Confused ? me too.
So here are the symptoms and my thoughts on the problem and solution...

If the engine starts okay, the tanks pressure builds to an astounding 30 psi, then, without my permission, the engine stops. If the engine doesn't start right away the tank pressure still builds and prevents the engine from starting. So I vent the tank and then the engine may or may not start but the tank pressure always builds.

I think it is the continuous run load governor/unloader, not unloading. I have read that this can be adjusted and or, of course, replaced. I am not sure how to adjust it or what to replace it with (I have read about the Load Genie???)

To me this is a puzzle I am still enjoying...

"I know what I don't know is alot... a whole awful lot"
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Old 08-06-05, 02:08 AM
DIYinOR's Avatar
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Found a crack

This Forum has helped me understand air compressors more than any other source. After continued research I was sure that what Speedaire calls the "constant speed unloader" was the problem. So with better lighting and my fingernail, I found a crack on its darkest remotest side. It looked like a casting seam at first. So now I need help with my solution...

Should I replace the Constant Speed Unloader with the same part???
And if so is Grainger the best source for Speedaire parts???

Or can I replace the Constant Speed Unloader with the "Load Genie" I have read about???
And if so will I have make some modifications? This compressor has a manifold above the tank where the Unloader, Check valve, Safety Valve, and Pressure Gauge all attatch. My impression of the Load Genie is that it combines the unloader and the check valve into one assembly, so I would have to plug one port.
Old 08-06-05, 07:54 AM
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I took a quick look at the Load Genie and it appears to operate differently than what I think you have now.

Tell me if this is correct:
Your Speedaire should have a valve that senses tank pressure and opens an outlet when the tank reaches pressure. This outlet would be connected to an air cylinder that then pulls back the engine throttle to idle while at the same time vents a small amount of air from the discharge line.
The Load Genie is meant for electric compressors and wouldn't do what you want.
I built my gas compressor from scratch and unless you are a glutton for punishment I don't think you want to go there.

Graingers would be a good place to go for the original part you need.

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