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Air compressor leaking Help

5K views 9 replies 4 participants last post by  Yogi89 
#1 ·
Just picked up a 1965 champion 5hp 80gal 1ph 240v 2 stage air compressor. Problem is when the pump kicks off I have a slow air leak through the breather tube. If I turn the pump off it will leak till the tank is out of air. I have no idea where to start.


Thanks for any tips!

Yogi
 
#2 ·
Start by making ABSOLUTELY SURE there is no pressure in the tank and then remove the line from the pump to the tank. The odds are that the backflow valve in the tank where the line attaches to it is leaking and will need to be replaced. This is a common problem and those valves are fairly easy to find, if no one close by sells compressor parts you might try Surplus Center as they usually have about anything you might need.


www.surpluscenter.com/item.asp?item=4-1770&catname=

www.surpluscenter.com



Make sure that tank is EMPTY before removing that line/valve since even a few PSI can hurt you!
 
#4 ·
There is no doubt that valve is leaking, or simply missing, otherwise air could not flow back to the pump. Sometimes someone will change a tank or pump and not put the valve back in place but it must be there and working properly or you will get the problem you have. Even worse would be the pump having to start up under a load because the unloader on the switch would be unable to bleed off the head pressure, since you did not mention a hising sound or air leaking from anywhere but the pump I am wondering if your unlader is also malfunctioning or missing? The unloader should vent the pressure from between the pump and the backflow valve in the tank when the compressor builds up to shut-off pressure. It is normal for air to leak (that's how it works) from the unloader for a couple of seconds when the compressor shuts down and if it don't the the pump is likely to be starting under pressure which will overload the motor and eventually cause problems.
 
#5 ·
My check valve is definitely leaking. It looks nothing like you showed me though Oldred. This valve looks more like a plumbing back flow valve. It is original to the compressor. I am going to order one now.

THANKS a million Oldred. Can't wait to get this thing working so I can get rid of the craftsman oilless compressor.
 
#6 ·
When you have one of the iron type check valves its not unusual to have to take it apart and clean the disc and seat once in a while. They typically have a top cap with a square or hex lug that will unscrew so you can remove the disc and spring. A little piece of carbon can stick in the seal area, keeping the disc from fully seating. I've got an iron check on the 15 hp compressor in my shop and have to clean it about once a year on average.

On the brass checks like red mentioned, I've found the only thing to do when they leak is replace them. They've usually got a teflon seat, and when they leak back there's no cleaning or fixing them.
 
#9 ·
Hey Yogi...that Craftsman oiless rig a "LITTLE" noisy?? I had one, supposedly 6.5 hp w/110 v.??? What a bunch of crap, I literrally had to wear ear plugs when that thing was on. I have a 60 gal. 5 hp 220 v. rig now, much quieter and much more air........good luck.
 
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