# Compressor Question



## CJKarl (Nov 21, 2006)

I'm usually over on the Masonry side, but I picked up a Lindsay 40 cfm compressor and I'm trying to get info on it.
Does anyone know where I can get more info? I guess Lindsay is out of business.
Cleaned the carb and it's running great, but I don't think the pressure shut-off is working. Need to troubleshoot that.
Here's a photo.
http://i264.photobucket.com/albums/ii197/kkaufmann1/20141227_113533_zpspxtojv5g.jpg

and a video of it purring like a cat. 
https://www.youtube.com/watch?v=Ur0AAPxf74s&list=UUw2SswV4YAr7q4NdVnJAIrg


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## tgeb (Feb 9, 2006)

What exactly is it doing?

I watched the video, it sounds like it's running fine. 
All these compressors have an "unloader valve" the compressor goes into bypass after it reaches a certain pressure so it does not blow itself up.

I would have to assume that either the valve is working properly and is un-loading or the valve is staying open and not building pressure at all? 
The other option would be the compressor itself is bad and it is not building pressure at all.

What is the issue?


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## CJKarl (Nov 21, 2006)

After about 30 seconds with all valves closed an the compressor engaged the engine starts to labor. As if it is building up too much pressure. It doesn't sound like the pressure switch is disengaging the compressor.


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## tgeb (Feb 9, 2006)

Ok, do you have a pressure gauge attached so you can verify the actual psi that it's producing?

It sounds like the unloader is not working properly, which should be easily replaceable or repaired. Identifying it might be an issue.


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## tgeb (Feb 9, 2006)

Looking at the pic you posted the unloader is probably located to the rear left of the photo. It has a brass tube running toward the front. Easy to spot.

I'd disassemble and check the tubes to make sure they are clear of debris. Make sure there is no pressure in the system before attempting any dis-assembly.

What does the lever/handle above the compressor do?


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## Morning Wood (Jan 12, 2008)

Can't help, but that thing is sweet.


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## CJKarl (Nov 21, 2006)

Need to replace the pressure gauge. Its stuck in the middle. That's the 1st thing I'm going to do. Ill get a pic of the pressure switch also . It has a silver button that I was able to pull up with pliers with some pressure in the tanks. Air, dirty water and crap came out. This unit sat outside for a year before I got it.


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## CJKarl (Nov 21, 2006)

The lever on top engages/disengages the pistons on the compressor side.


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## CJKarl (Nov 21, 2006)

Or I guess the correct answer is engages/disengages the blowby.


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## CJKarl (Nov 21, 2006)

Couldn't get it started today. :sad:
Time for the carb rebuild kit. Anyway here's a pic of the valve.


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## CJKarl (Nov 21, 2006)




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## tgeb (Feb 9, 2006)

Ok those pics help.

The valve with the tube coming off of it controls the compressor. When the pressure in the tanks reaches a certain limit, the valve opens and charges air into the tube.

If you follow the tube it leads to the heads of the compressor cylinders. 
There is a mechanism inside the head that when charged will hold open the intake valve, which causes no more air to be pushed into the holding tanks. 

Once the air pressure in the tanks drops below a specific amount, the valve closes, the intake valve functions as normal and the pressure will build again, this cycles on and off as you use the air.

You need to test/inspect the entire circuit. I would start by disconnecting the tube right at the valve and pressurize the system to see if the valve opens. It looks like it is an adjustable valve and maybe some tweaking is in order.

Once you verify the valve is functioning properly, reconnect the tube and test run. If it does not function properly make sure the tubes are clear and have no leaks, next would be the mechanism in the head.

Another item of concern is the third tank tank, (last one on the left) has the pressure relief valve in it. I would replace that, as it is designed to blow off if the system pressure goes beyond what the machine is designed for. If it does not relieve the pressure and the compressor continues to build....you have a bomb on your hands.

Me personally, I would do the testing and pressurizing with another compressed air source if you have one available. Less chance of something going amiss if you take the engine and compressor motor out of the diagnosis until you are comfortable with the relief valve system.

Let us know how things go.


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## CJKarl (Nov 21, 2006)

Thanks for all that info.


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## CJKarl (Nov 21, 2006)

After work tonight I pulled off on of the tank drains and installed a nipple and hooked my electric Crapsman compressor to it. Pumped her up to about 110 psi. I slightly lifted the pressure relief slightly and it popped, emptying all the air. It seems to work good. Doesn't seem to be sticking. I refilled the tanks and heard air leaking from the control valve. It now looks like someone was in there for some reason. Tomorrow I will take that apart and inspect. Then follow the air to the compressor heads. I'll get this going.


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## tgeb (Feb 9, 2006)

Being able to hear leaks is one of the reasons I suggested using another source for the pressure. You never be able to hear a small leak with the engine going.

I have also been thinking that you could "test" the heads by removing the line at the control valve and hook up pressure to the line, with a hand valve you would be able to see if the rest of the system is working.


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## CJKarl (Nov 21, 2006)

That's my plan. I'm going to take the line off just after that valve and rig up some kind of nipple I can inject air from my electric compressor into. So if the blowby on the cylinder heads are working they should engage somewhere around 100-120 and let the air out? That would be easy to hear.


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## tgeb (Feb 9, 2006)

No, That's not correct.

The mechanism in the head when pressurized holds the valve open, pretty sure it will be the intake valve, as long as the intake valve is held open pressure will not build. The air goes in the intake, then right back out, because the valve is open.

When you pressurize that line past the control valve you will probably here a click up in the head, I doubt there will be any air leaking up there. But you should hear the engagement.

Probably won't take a lot of air pressure to make the mechanism in the head work.


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## tgeb (Feb 9, 2006)

If you have air leaking at the control valve, that is probably the issue. That valve also looks like it is adjustable and it could be set to high. But it should not leak.


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## CJKarl (Nov 21, 2006)

Thanks again. I pulled the lines off yesterday, sprayed penetrating oil in everywhere I could , then put the lines back on. Hopefully I hear some clicking/engaging.


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## CJKarl (Nov 21, 2006)

I'm a pretty logical guy, but I don't know if I trust myself to pull a head off a cylinder. My take it to a compressor shop. I only paid $400 for it, so even if I have to dump $500-$1000 into it, I'll still be making out.


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## tgeb (Feb 9, 2006)

Have you been able to get the engine running again?


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## tgeb (Feb 9, 2006)

I doubt the problem is in the heads, those systems are pretty reliable.

I'd pump the tanks up with the small compressor to the 110 psi or so that you did before, then adjust the control valve until it opens, then put it all back together and test run it. 

It should then build air to 110 psi, cut out, then build air again after the pressure drops.


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