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Rol-Air Compressor not filling tank.


Legal v8's Avatar
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10-01-07, 06:09 PM   #1  
Rol-Air Compressor not filling tank.

Rolair model GD4000PV5H
(pump model # PMP11MK238FI)
Honda GX120 Engine Model: GC01-2326847 QX2

I tore the engine apart to get it running, which it does now. Took the compressor apart to clean all the gunk out of it. I reassembled everything and now the compressor does not fill tank. The reed valves are not broken or rusted. inlet and outlets on the compressor head are clean. Compressor has 5w-20 oil in it for now. Any ideas? I havent taken it apart yet but if anyone has any experience with Reed valve type compressors, let me know.. I'm eager to get this little devil working properly.

 
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cheese's Avatar
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10-02-07, 08:04 PM   #2  
Can you manually turn the pump and feel air coming out the outlet? The pistons move, right?


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God bless!

 
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10-03-07, 04:22 PM   #3  
Yes, Everything moves. The unit did not run when I got it. I did a carb job and now the engine runs pretty well. The compressor is pumping but I dont get any pressure in the tank. With the engine running, there is air coming out of the outlet but I can put my finger over the outlet and can stop the air coming out. I tried running it with the intake filter off, no different. The reeds look good and are not rusted. I had the entire compressor apart and cleaned everything and put it back the same way it came apart.

 
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10-04-07, 11:55 PM   #4  
Sounds like a reed valve is not working. You shouldn't be able to stop the flow of air on a worn out compressor with your finger, let alone a good one. Is it configured so that you can test reed valve operation by blowing/sucking on the outlet pipe?


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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10-05-07, 06:10 AM   #5  
You can check the rings by blocking off the compressor outlet and looking for pressure coming out of the crankcase vent.

There could be wear in the reeds and the valve plate as suggested.
In some heads it is possible to reverse the reeds but does not often help.

If the reeds are slightly worn and you have patience you could try lapping the reed and valve surfaces with automotive valve grinding compound.

The correct oil to use would be 30 weight non-detergent motor oil available at most auto supply stores.

Valve plate kits are available but I could not find any reference to Rol Aire and I am unsure if its history or who made them.

Cambell Hausfeld valve plate:

Image courtesy of jackssmallengines.com

You can start at a supplier like this one to locate parts.


GregH.........HVAC/R Tech

 
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10-05-07, 06:39 PM   #6  
The reeds arent bent and the head appears to be in good condition. I used RTV glue on the gasket surfaces to make certain it was sealed will. I had the piston, connecting rod and cylinder all apart to clean it. still has hone marks in the cylinder and the piston to bore fit is pretty tight.. I had to use a ring compressor to install the piston in the cylinder. here's a link to a site that sells this particular compressor and also a link to the exploded view of this unit.

http://www.toolbarn.com/product/rolair/GD4000PV5H/
Compressor Schematic
http://www.rolair.net/schemes/GD4000PV5H.pdf
Pump Schematic
http://www.rolair.net/schemes/MK238.pdf

 
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10-06-07, 05:40 AM   #7  
Hi:

I have the 1 HP electric version of this compressor. It is my understanding that the pump assembly is made by "FINI"(think that is the spelling)- an Italian manufacturer, and is the same pump that is/was used on many of the Emglo portable compressors. Hope this helps you find replacement parts.

Bob

 
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10-06-07, 02:20 PM   #8  
I think I've been into one of those pumps. I think all components of #42 must be oriented in the proper position (I think there may be a peg or two that lines up the holes). Also, the liquid gasket sealant you used could be a part of the problem. It's not a very good pump IMO. (no offense intended).


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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10-06-07, 02:51 PM   #9  
cheese: it may not be a very good pump, but it was *free*. I am going to get some new gaskets and maybe some reeds and try it again.. those two things are the only thing that can make it not work properly. I'm gonna see what I can do with it today.

 
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10-07-07, 01:12 PM   #10  
Good news. After replacing the gaskets yet again I now have pressure! it fills the tank to 140psi effortlessly and quietly. I do have to order the throttle-down valve as mine doesnt have it.. but I want to thank you guys for your input.. I feel like since it was just a stupid gasket.. but nonetheless it works.

 
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