Shoebox Rebuild – Help Needed

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jonpol

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Dec 10, 2019
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Ohio, United States
I use my Shoebox almost weekly to top off my tank and I’ve re-built it a few times over the years. Today, when I went to use it, it would only pump up to 1500 PSI. It would continue to run but the pressure did not increase. I assumed it was time for a rebuild. After rebuilding, I started it up and got the same results – 1500 PSI and, no matter how long it ran, 1500 PSI was the max it would go. So, I spritzed it with soapy water to see where it was leaking. I found it was leaking at the base of the air block where it attaches to the sheet metal frame. I’ve never seen or heard of this happening. Before I rip everything apart, does anyone know how to fix this? I’ve attached a picture of the problem. Thanks in advance for any help you can provide.

Jon
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I would say that it may be the O-Rings at the bleeder valve, which is underneath the flat plate on the back of the aluminum block actually, there is another O-Ring there too.
Please look at the schematic in this thread and you'll see what I'm talking about.

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Vent assembly #37. Be forewarned that there is a small spring and two steel balls inside of the block underneath that flat plate, so use caution when removing. And don't get too frustrated reinstalling them! I don't use the Box venting as I vent through my water filter instead. I did use it for a short time and that's how I know what the issue likely is!
I am actually surprised that it's not leaking from the vent hole seen just above the stainless steel connector. Looks like you have an early model as the later ones don't have that big coil of tubing on them.
mike
 
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I followed your suggestion and completely cleaned and re-built the vent assembly/bleeder valve. When I tried it out, it only went to 1500 PSI again and was still leaking at the base. There's a plug on the bottom of the air block which does not appear to be removeable or adjustable. That's the only area I didn't work on but, it's a fixed part. I may just make a thin gasket for the base and see if that solves the problem. If nothing else, I'm getting good at tearing this thing apart.
The other thing that doesn't add up is why does it always top out at 1500 PSI???? Also, why is it not leaking through the vent hole?
Anything else that you can think of?
Thanks for your help,
Jon
 
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Perhaps the burst disc has blown. It sits on the backside of the aluminum block.
I made it an easier fix by drilling a 1" diameter hole (hole saw) through the back of the red sheet metal at the disc location. Makes it super easy to put a ratchet with extension through that hole to remove and replace.
Amazon has the burst discs, buy 6 of them for around $20 or so. They are 7.5K PSI discs.
mike
 
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Years ago, I had leaking at the base of the air block a few times. The leak was caused by a bad oring at the base. I pointed to it below. Took me a couple of times to get it to seal up correctly after replacement, but so far it's been holding for quite some time................ probably just jinxed myself. Hope this helps!

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isledweller said:
Years ago, I had leaking at the base of the air block a few times. The leak was caused by a bad oring at the base. I pointed to it below. Took me a couple of times to get it to seal up correctly after replacement, but so far it's been holding for quite some time................ probably just jinxed myself. Hope this helps!

View attachment 291662
Click to expand...
I replaced that stupid little O-ring the first three times I ran my F10 (I was happy I ordered a bunch of spare O-ring kits). After that I added another air filter after the dessicant filter on the input side, assuming I was getting some particulate through the system causing the issue. While I don't know if that was in fact the cause, I have had no more issues since I did it. Heck, I'll bet my F10 has as much as 12 hours on it now. :)
 
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