[Rickracer]

We just got this compressor from the estate of a friend who passed away, and it works great, but it has a leak that is hissing out of the intake filter. It has an automatic compressor drain that apparently has been disconnected. If I plug the air leak in the intake manifold with my finger, it starts pushing oil out of this little device that's mounted between the pump and the motor. I would like to restore the original auto drain, and fix this leak. I checked the company's website and don't see any type of owner's or service manual, so I thought I'd check here to see if anyone could shed any light. I think the pics pretty well ask the questions. I'll appreciate any insight, thanks,

[LATECH]

Well in the first picture the device you point out has a line to what appears to be the crankcase of the compressor. I would suspect (only my opinion) that it is an oil seperator or crankcase vent or both.May be working properly.If it keeps getting pressure all the time maybe the reed valves are not holding (or whatever valve type) and some pressure is bleeding back into the cylinders and past the rings.
Does the conduit next to it have wiring that hooks to it? where is the pressure swith on this model?

[LATECH]

the auto drain tube could have hooked to the " T " you have pictured I guess. It would make sense that there is a tube inside that goes to the bottom of the tank as that is where the water would go. The auto drain valve appears to have an expulsion nozzle aiming straight down from the bottom of it. Look to see if the bottom of the tank has a drain plug.
The only way it would make sense for the autodrain to be hooked to the side of the tank like you point out would be if it had a pickup tube inside the tank from the bottom of the tank inside to the T fitting on the side.
Also the oil in the sight glass on the compressor looks white- ish.Does it have water in it?
Where is the pressure line from the compressor at? ( From the tank?)

[LATECH]

could the device in the first pic be the low oil switch? that would make sense . especially with the wire hooked to it.look at the wiring from it does it share wiring to the pressure switch? if it is wired in series twith the compressor control it is probably the low oil cutoff.

[Rickracer]

The device in the middle could have been a low oil cutoff, but that's been disconnected (electrically) as well, although the conduit is still there for the wires. Right now, we just have a toggle switch connecting the two wires, (which gives us a handy shut-off), replacing the wire nut that was on it when we got it. The oil sight glass has a little aluminum plate behind it, that's what you're seeing there. The oil is nice and clean, and full to the line. The pressure switch is a regular Furnas controller like 99% of all compressors have. The bottom of the tank has a petcock, but so does the tee in the side of the tank, and either or both will drain when you open them, so there is definitely a pickup going from there to the bottom of the tank. I suspect that head pressure, fed by the unit pictured on the sticker, activated the auto drain valve, which is apparently missing, and has been replaced with a pipe plug. There was an aluminum tube going from the auto drain "control valve" down the the tee, but not attached, just hanging there near it, I have no doubt that's where it went originally. I'm thinking the key to the whole mystery is the round unit on the side of the pump, which I think controls where head pressure is directed, and I suspect the actual leak is inside it.

[oldred]

Your problem is the backflow valve in the tank where the air supply line from the pump connects to the tank. This valve is a fairly common problem as it tends to leak and allow air pressure to flow back into the pump when it reaches shutoff pressure and the pump shuts down. The unloader has also apparently been disconnected otherwise in addition to the air leaking from the intake you would also be getting a loud hiss from the unloader, apparently that was happening and instead of fixing the problem they just disconnected the unloader valve-a real no-no which can burn out your motor!. With pressure leaking back from the tank to the pump air will flow back past the valves (they do not normally seal 100%) and leak out the intake as you describe. If you plug this leak in the intake pressure will then build up in the crankcase and force oil out like you are also describing.

The system works like this, when the compressor reaches cut-out pressure and the pump shuts down the unloader valve will bleed the pressure from the pump supply line to the tank and the pressure from the pump itself and will also prevent tank pressure from reaching the pump, there will be a loud momentary "hiss" when the pump shuts down on a normally working compressor from the pressure being bled off. This is done to prevent the pump from having to start under pressure which will exceed the motor's designed starting load usually resulting in serious damage in a short time. First you need to remove the line from the pump where it goes into the tank and either repair or replace the backflow valve, then you MUST reconnect the unloader to relieve the pressure on the pump during start otherwise your motor will be damaged! When you repair/replace the tank back flow valve the leak from the intake will stop but you will have a momentary leak (a second or so) from the unloader if it is working properly-this is normal and if it does not happen then something is wrong. Doing these repairs will fix the problems you have including the oil leak, you should do this before running the compressor any more or you could very well be in the market for a motor soon!

[Rickracer]

You were correct about the tank check or backflow valve, looks like it hasn't been seated in a LONG time. Not sure I can restore this one, probably going to need a replacement. I just talked to Champion and they are emailing me an owner's/service manual. Kudos to them, great customer service, even though I'm not a regular customer, they are taking care of folks that own their products,
This machine doesn't have a "normal" head pressure unloader at the pressure switch, but it's got one, and it's working, because it starts every time with no problem at all. I'm really curious to see what that round component is on the end of the pump, it has an arrow showing the direction of rotation, and tubing that connects it to head pressure, but I have no clue what it actually does, it may be the unloader. Hopefully, the manual will shed some more light on what does what. Thanks guys, I'll let you all know what I find out,

[oldred]

Unfortunately the motor starting every time does not always mean the unloader is working properly, if you don't hear the "hiss" from the air pressure being bled off when the pump shuts off then it probably is not working properly. I have seen this a lot, the unloader will continue to hiss after the pump shuts down because of the faulty back-flow valve and the owner will simply plug the line to stop the leak, he then discovers the compressor seems to be working fine and will continue using it without fixing the back- flow valve but usually motor daamage results after a while. If you are getting that momentary air discharge at shut-off then everything is fine and there is no problem but if not then by the time the motor starts to stall out at start up it will be too late. On a cheap compressor with a motor that is barely up to running the compressor with everything working except the unloader the motor will usually try to stall and and the pump will start out slowly or the motor will just simply stall out completely and not start at all, usually tripping the breaker. On a better outfit such as the one here the motor will usually have quite a power margin and in most cases seem to start normally but if you put an AMP meter on the wiring the reading will be way too high at start up which can seriously damage the motor after a while.


Of all the motor problems we ran into by far most were caused by a faulty or owner disabled unloader valve and in just about every case where the owner had plugged the valve it was because the back-flow was leaking and they did it to stop the hissing sound after the pump shut off.

[27 t]

I'm really curious to see what that round component is on the end of the pump, it has an arrow showing the direction of rotation, and tubing that connects it to head pressure, but I have no clue what it actually does, it may be the unloader. Hopefully, the manual will shed some more light on what does what. Thanks guys, I'll let you all know what I find out

That is the governor housing (Positive acting, governor-type centrifugal unloader) ..not a 100 % positive on what it's main function is but thats what it is...

[Rickracer]

Originally Posted by 27 t

That is the governor housing (Positive acting, governor-type centrifugal unloader) ...

That is correct, and it IS working. I couldn't hear the hiss of it unloading over the hiss from the intake leak. I WAS able to restore the tank check valve (anti-backflow valve), and that was all it took to stop the intake leak. Now, when I get some more time, and do a little more research in the manual, I'm going to restore the low oil cutoff and the automatic drain functions as well. Thanks for the help gentlemen,