Champion Compressor Low Oil Level switch question

[Todd.Brock]

Hey all,



I recently acquired a couple more Champion compressors. They both have low oil level switches. The switch is not wired into the magnetic starter. I started it up for the 2nd time last night after fixing some leaky fittings. I kept hearing a loud leak and found it is coming from the oil level switch. There is a hole in the top of the oil level switch… There is a line plumbed from the unloader to the unit and then back into the head. I would really like to just remove it and plug the hole in the side of the case. For reference, the 2nd compressor I bought has the same set up. It’s a 3 phase unit so I can not test it.





IS anyone familiar with this ? I assume since the hole is present in both switches, they serve a purpose. The tank filled to 100 psi in about 7 minutes even with the leak, so I assume it will be pretty good pump…



You tube Video

Pics of Pump in question.

Pic of pump in question line routing

Reference pump (3 phase unit)

 

[malibu101]

I recently acquired a Champion compressor and one of the problems was the oil level switch doing the same thing as you describe. My oil level is fine but still had this issue.

I simply disconnected the line from the pump to the switch and plugged the tee on pump where the line came from. I left the line from the switch to crankcase intact. I also removed the wires you see in the above pic and wired them together in the starter.

I have no problems and mine fills from empty to 135PSI in a about 7 minuites too, with no leaks.

 

[Todd.Brock]

Malibu, any thoughts on what causes that?? Thanks for the info by the way.
I am not sure what all the lines going to the switch are for. I was going to redirect the pipe from the unloader to the switch directly to the head. Just bypass the switch all together. What you did, capping off the line at the unloader eliminates the extra route, but leaves a connection between pump and switch. Is there a concern about the line going from the pump to the oil switch bleeding air , etc??

Good looking compressor. You have all the accessories. I took off the champion drain and put a simple pet **** for water to drain. I did this so I could eliminate complexity. I just plugged the bucket drain hole. All of copper air ines were missing, corroded or plugged. I have the bucket drain tube and the diaphragm. I may try it again at some point. I just wanted to see if the compressor was useful/functional before messing with oil switches and auto drains ...

 

[malibu101]

Well, another one of the problems with this compressor was that the auto drain kept leaking air. Turns out a seal (washer) was bad inside the autodrain. So I no longer have the autodrain. I just put a ball valve on the bottom and will manually drain it. That's why you see a gauge where the line used to connect. A gauge was all I had to plug the hole.
On the pump, where the line went to the unloader is now just open so it can let air escape when it's done running. If your compressor did not have an oil switch there would be a muffler there from the factory.

Oil level switch- No air leaks as I have it now. It works great. I did not want to mess around trying to remove the switch from the pump and then sealing the hole in the crankcase where the switch was so I just left it there and there are no leaks (air or oil) at all.

EDIT- Link to my original thread when I got this. http://www.garagejournal.com/forum/showthread.php?t=246956
Update to the above link- I am now running it on a rotary phase converter with no problems but of course that is an electrically expensive way to run it.
I am on the lookout for a single phase real 5HP motor.

 

[Todd.Brock]

Thanks again for the info. I know you can get a rebuild kit for the auto drain that has new seals. My compressor has oil residue over the back of it. I presume from the oil switch. The crank seal looks good. I will wipe it down and see how bad it leaks. I think my other champions that didn't come with the oil switch just had a plug in that spot. I will have to hunt down my old pics.

 

[b-body-bob]

I think my other champions that didn't come with the oil switch just had a plug in that spot.

Mine has a plug down low on the right hand side viewed facing the unloader., if that's where the oil pressure switch goes. I'd post a photo but they're all pretty bad.

 

[Todd.Brock]

Yup, that would probably be it!!! I just filled it with new oil and I don't feel like draining and messing with it all. Unplugged and capped off it will be!!

 

[malibu101]

My current configuration.
The pipe for a "plug" is crimped and soldered so air can not go through it.
Eventually I will get a 90 fitting but this works for now.

 

[jscott14]

IS anyone familiar with this ? I assume since the hole is present in both switches, they serve a purpose. The tank filled to 100 psi in about 7 minutes even with the leak, so I assume it will be pretty good pump…

I know this is too late to help Todd out, but from the department of better-late-than-never, I wanted to offer more of a definitive answer on this so that others can benefit. High pressure air should never get to to where it's leaking from. There is an o-ring that should prevent it. However, when that o-ring goes bad/missing, you'll get a lot of high pressure air where you don't want it, so they have that little bleed hole in the housing to prevent it from pressurizing the crankcase of the compressor pump.

To everyone who is wanting to bypass these low oil switches, I would urge you NOT to... they're really simple, and most problems can be fixed with either an o-ring, a spring, or a cleaning. That's it! I'll try to explain how they work so that they're de-mystified. (I might even make a YouTube video explaining it, because that will be MUCH easier to follow.)

First, let's get the schematics in front of us for easy reference:

Todd's problem is very simple. Part #12 (an o-ring, part number M-1598) is bad or missing. Here's an actual photo of that piston with the o-ring:

Between the diagram and my photo, try to follow along with how these work, because they're quite simple. The air line that comes from the unloader/head feeds high-pressure air to the right side of the low oil sensor (under the great big hex nut cap, #9 in the diagram).

This high pressure air tries to push the piston down (or in this case, sideways). The air isn't "going" anywhere. It shouldn't be flowing. It's ONLY pressurizing the chamber to force that piston to move. If the piston can move all the way without obstruction, it will push a tiny button on the back of the mechanical shutoff switch (#16) and break the circuit. This will cause the motor to shut off.

But notice that perpendicular to this piston is our float (#3) which has a metal rod sticking out the top of it (#2). IF the float rises high enough (that is, it floats on oil to rise), the metal rod (#2) rises up into a passage that mechanically blocks the piston (#10) from moving. Air pressure is TRYING to move the piston into the shutoff switch, but it can't do it because the float rod is blocking it. It's really that simple. There's a spring on the piston so that when the compressor kicks off (i.e. pressure is bled off) the piston will return to the "top" of its stroke.

You might also be wondering what that SECOND air line is on top of the low oil sensor (the one that routes to the crankcase). That's just a crankcase vent to equalize pressure. If you had really worn pump pistons, you'd get some blow-by of air into the crankcase, essentially pressurizing the crankcase (which the low oil sensor is a part of now), so this little pipe would just vent that positive pressure back to the crankcase. We'd certainly leave that in place, but under normal operation, this isn't much of a concern for us.

Now, the designed operation of this low oil switch has one odd effect (odd to me, at least). Since it relies on positive air pressure (from compressed air) to push the piston into the stop switch, this means that the sensor WILL let the compressor run, even if there's not a drop of oil in the crankcase! You could drain the oil, forget to fill it back up, and turn on the compressor, and it would happily fire up... up until the point that enough each pressure is developed to push the piston far enough to overpower the spring and depress the mechanical kill switch. In reality, this should only take a matter of seconds, but it still seems to me like an odd behavior. Put another way, this oil switch relies on TWO variables to be in place before the switch will trip:
1. Low oil level
2. Adequate head pressure delivered to the low oil piston/plunger.

I don't know why Champion chose this design over a simpler float design that breaks a circuit based ONLY off oil level. I'm sure they had a reason... I just can't think of what it might have been.

Anyway, I hope this is helpful so someone else who is thinking about bypassing their low oil switch.

 

[SSolomon]

Hi jscott14, I know this is an old thread, but I was searching around for info on this same leak happening to my compressor and found your diagram and explanation, which were really helpful. Thanks.

 

[oilslick]

Google brought me to this thread @work. Our 10hp champion compressor tripped the low oil sensor. I couldn't view these pictures but using the directions solved my problem. Ours had an o ring worn flat. Thanks for the help.

 

[apruitt9]

Bringing back a old one! I have a Champion HR10-19 and the wires have been cut that run to the oil switch. Does anyone have a wiring diagram they can share or tell me where the wires go? Thanks!!

 

[Shoreline_]

Its a normally closed switch that runs in series with the pressure switch control circuit and the motor overload circuit. Dont forget its latching so if you change the oil, youll need to cycle the white knob all the way clockwise for it to reset.

The OP is long gone Im sure, but that tube off the top is a vent tube so the oil level equalizes with the crankcase.

 

[apruitt9]

Its a normally closed switch that runs in series with the pressure switch control circuit and the motor overload circuit. Dont forget its latching so if you change the oil, youll need to cycle the white knob all the way clockwise for it to reset.

The OP is long gone Im sure, but that tube off the top is a vent tube so the oil level equalizes with the crankcase.

Thanks!
Here is what I am working with, where do the red wires from the OPS connect?

 

[Shoreline_]

Like this is ok. Take the long red from the oil level switch and stick it in a1. Take the short red and wire nut it with the black wire thats in a1 already that you will remove.

 

[apruitt9]

Anyone have a wiring diagram for future reference?

 

[Shoreline_]

Anyone have a wiring diagram for

I can probably dig through a shop manual for you but its really basic. Just wire the switch in series with the pressure switch. Are you comfortable doing that?

 

[apruitt9]

I can probably dig through a shop manual for you but its really basic. Just wire the switch in series with the pressure switch. Are you comfortable doing that?

Got it! Just wanted a manual for any future reference for my service guys! Thanks!

 

[Shoreline_]

Its a great machine make sure you dont run engine oil in it! Good luck

 

[RTM]

Rumor has it this wiring diagram from a Speedaire should get you close.




From this manual

Speedaire 10 and 15 HP 2 Stage Air Compressors Owners Manual | PDF | Valve | Implied Warranty

Speedaire 10 & 15 HP 2 Stage Air Compressors Owners Manual and Parts Manual

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