# Issues With My Champion R15B Building Pressure Slowely



## niferous (Nov 11, 2015)

I have a compressor that uses a Champion R15B compressor and I'm having issues with it taking a very long time to build pressure up. it has an 80 gallon tank and uses a 5 HP, 1740 RPM, 15 amp motor to power the unit with a capacitor start. It originally had a three phase motor that I took off since I only have single phase power. I have attached the spec sheet for the unit. Currently I have all my air lines plumbed and hooked up to the tank but I've got a ball valve on the tank where the line comes in to make sure I'm not feeding some leak inside my garage (I made a sound enclosure shed for the compressor behind my garage).

I bought the compressor used from the Army in a surplus sale and didn't pay too much for it. It was in good working condition when I got it but it was developing some rust in spots and I wanted to learn more about the inner workings so I decided to perform a rebuild on it. I figured I had less than $200 in the whole thing and it would be a good learning experience, which is has been. Any how I got a rebuild kit and disassembled everything. Then I rebuilt everything with new fittings, new fasteners, seals, etc. 

When I turn on the compressor it start just fine and builds pressure pretty quick up to about 50 - 60 PSI. Once it hits about 60 PSI it's very slow to build pressure from there on up. The other day I watched it until 60 PSI (took about 10-15 mins) and then went inside to take a shower and check on some other things. I came back about 25 - 30 mins later and the compressor was only at about 80 - 85 PSI. I let it run a little longer while checking for leaks. I found one leak on the line that runs from the high pressure exhaust manifold down to the centrifugal unloader. I went ahead and just bent some new tubing and installed a whole new line. Once I did that I turned the compressor back on and it got up to 100 PSI but it still took about 20 or so minutes to do so. 

One thing I've noticed is that the unloader valve on the bottom of the centrifugal unloader is just purging air the whole time the compressor is running trying to build pressure. I have attached a schematic where I drew a red arrow to the valve I'm talking about.  It's really nothing more than a breather. The manual calls it an "unloader body" and it's part number 13 on the drawing. My understanding is that during operation the unloader valve will open on start up to take pressure of the valves and once the compressor reaches a certain RPM the valve will close. This is done via a set of weights that open and close based off of the RPM of the crankshaft. So since this breather is constantly blowing air out is it safe to assume that either I have rebuilt the valve wrong or that the compressor is not reaching the needed RPMs to close the valve?

I'm pretty sure the valve was re-installed correctly so I wanted to ask if my choice of oil could affect the RPMs? From what I've researched Champion specs a 30W air compressor motor oil and I'm using Catoil. It's really hard to find out what viscosity Catoil is but I've been told by a few people that is it top grade stuff which is why I used it. What I've noticed is that the stuff seems so lite that it is leaking through seals and just oozing out everywhere. Does anyone think it's worth it to drain this stuff and just go with a standard 30W air compressor oil or has anyone used Catoil and known it to be effective? Here is the Catoil testing data: http://catoil.biz/CatOil%20Testing.pdf Looking at their website I'm not so sure I was given good advice and this stuff may be best used for other applications than in an air compressor. 

Sorry for the really long post, I just wanted to provide as much detail as I could. I hope someone can offer some insight as I'm a little stumped and I really don't want to have to tear back in to this thing chasing down who knows what to try and get it working.


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## niferous (Nov 11, 2015)

I went ahead and changed the oil on my air compressor since I had some and I figured it sure wouldn't hurt to do so. I started it up and once again checked for leaks on the manifolds and other connections but didn't find any. I had just got done working out so I went ahead and started it so it could run while I was taking a shower. I let it run for over 30 minutes, and checked it every 10 - 15 minutes. When I started it the tank had about 80 PSI and after 30 minutes of continuous running it had about 105 - 110 PSI. That just seems like an inordinate amount of time to be running and produce less than 30 PSI. 

Each time I went out and checked the little breather under the centrifugal unloader and it was steadily discharging warm air. Again, any help is appreciated.


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## tractornut (Sep 17, 2010)

Sounds like there is definitely a problem in the unloader it shouldn't be leaking air when the compressor is trying to build air


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