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compressor again

J

Jimmy Buffett

Active member
Yesterday my compressor started leaking. It is coming from the little switch that turns it on and off. The switch that looks like a tire valve sort of. We have had lines out into the road for the last 2 days so I have not been able to try to do anything. My auto uses a lot of air. It is a vertical Curtis unit with the motor on top. There is a copper pipe down under the motor and I'm assuming that is where the bad valve is. I can smell my motor the last couple of days so I ordered 1 yesterday just in case. That will not address the leaky valve though. It is supposed to rain tomorrow so I may be able to get into it. I will not however be able to get parts. Any suggestions to buy me some time?
Thx.
 
I have a backup plan when my compressor goes out. I rent a 2 stage wheel barrow style compressor from RSC (rental store) and hook it up to my compressor, this gives me the volume of air as normal.
 
The valve was mentioned in the other compressor thread. Assuming the bleed-off valve leaks all the time even when the compressor is not running, you'll need to change the check valve that's in the tank at the base of the large tube running from the head to the tank. If it leaks only when the compressor is running, only the bleed-off valve is bad, but you'll probably have to change the whole switch.

My "backup plan" for when the compressor is out is to let the smaller one tee'd into it take over. The bigger one is at a slightly higher turn-on pressure, so as long as the Ingersoll-Rand is running I know it's working. With six bays of self-serve equipment running many air pumps and an automatic that shuts down with no air, it was cheap insurance to have a backup inline.
 
I keep accumulating backup plans and parts but I never seem to have everything I need. I don't think that my motor issue is related to this leak. I think if I could find a spare tank it would lighten the load somewhat on my compressor. I'm going to take the check valve off tomorrow if it rains and see if I can get the leak to stop.
Thx
 
It may just be some debris in the check valve not letting the ball fully seat. I cleaned one out about four months ago and have not had a problem since (just happens it was a Curtis too). If I remember correctly, the valve body consisted of two pieces threaded together.
 
Mark,
It was supposed to rain today and I expected to work on this. Turns out I've got cars lined up again today. We had our best day ever yesterday. It looks like it will be very close to get that valve out w/out removing the motor mount. Please tell me that it will come out.
 
I wonder if this bad check valve could be responsible for my motor problems. I couldn't hear it till friday but it could have been leaking back into the pump causing strain on the motor. Think?
 
Jimmy Buffett said:
I wonder if this bad check valve could be responsible for my motor problems. I couldn't hear it till friday but it could have been leaking back into the pump causing strain on the motor. Think?
Click to expand...

It is possible. If you continue to have problems, I can get you in touch with my local Curtis distributor. He has ALLOT of info to share (hope you have free long distance). He is a very nice guy, but I actually think he talks more than me (I did not think it was possible for anyone to talk more than me).
 
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I took off the check valve this morning, cleaned it and put it back. It stopped the leak that I could hear. After that I shut down the compressor and took the small hose off that runs to the regulator(? the one that looks like a tire stem). There was no pressure there. I think it may be fixed. There is likely damage to my motor since I could smell it but I bought a spare. If I have more trouble I may need to call your guy. The guys in Lexington, my closest disty, know next to nothing about them. Thanks again!
 
If the leak was small, it probably had no effect on the motor. It sounds like the motor is just going bad and the leak was a coincidence. In order for it to be bad enough to put load on the pump, the check valve would have been stuck wide open, and the air leak would have been really noisy and impossible to miss.
 
If it were me and I had already bought the new motor I would install it. I would then take the old one to a motor shop and explain why you took it off and have them check it out and repair it if needed. Then stick it on the shelf for a spare.
 
It sounds like the unloader valve is not working. Its allowing pressure against the head which is putting an extra load on the motor causing the overload condition.
http://www.about-air-compressors.com/unloadervalve.html
Unloader Valve


Unloader valve; we've probably all heard one of these at one time or another.
Somewhere in the garage, the workshop or the plant, the "kathumping" of a reciprocating air compressor echoes throughout. Suddenly the thumping stops, and there's an audible... "psssssssssssschhhhhht", clearly the sound of air escaping, for just a couple of seconds.

That's the unloader valve, hard at work!

Plumbed into the lines between the compressor and the receiver , as part of the pressure switch assembly in most cases, the unloader valve will open when the air in the receiver reaches the set point.

Compressed air that's contained within the compressor assembly will be evacuated to atmosphere to prevent that pressure from affecting the start when the pressure switch again calls for air.
Compressed air, captured in the compressor after the pressure set point has been reached, would increase the load against which the electric motor would have to work when the compressor is required to re-start.
The unloader valve operates, "dumps" that air to atmosphere, and that problem is solved.

Sometimes the air evacuating from the unloader valve doesn't stop. Since it's in the air line between the compressor and the compressor receiver, there's a check valve between the unloader valve and the reservoir to stop the already compressed air from flowing back out when the unloader valve operates. If you have air bleeding from the unloader valve continuously, it's a good bet that the check valve had either failed or hasn't seated properly, and air is bleeding back up the line to atmosphere.
Click to expand...

http://www.phantasmechanics.com/air/air2.html

Let's start at the pump and look at the unloader/check valve. This keeps the air in the tank from pushing its way back into the pump after it stops. It also bleeds (unloads) the brass tube between it and the pump so that the pump can start easily. There are basically two types of unloader - this dual-duty version, and another that is fired by the pressure switch when the compressor shuts off - the kind seen most often.
Click to expand...
 
I.B. Washincars said:
MEP is correct. If that check valve is sealing there can't be any air at the unloader valve.
Click to expand...

Are they same thing in this compressor? Just because the tank check is holding, it doesn't mean that pressure in the line between the head and the check valve is being released. Jimmy, does the compressor make a "whooshing sound" when it shuts off?
 
I took the line loose to make sure that there was no pressure in it. It's ok now. Before I cleaned the check valve it was leaking from the unloader all of the time. Now the unloader only leaks when the motor is running and lets off pressure afterwards.
 
Jimmy Buffett said:
Now the unloader only leaks when the motor is running and lets off pressure afterwards.
Click to expand...
I just noticed this part - the unloader shouldn't leak when the compressor is running, only when it shuts off and only briefly. It will make your compressor run longer than it needs to each time it comes on, but I wouldn't attribute that alone to motor failure.
 
Did you find trash in the check valve last time? If not, it's sticking on its own and needs to be replaced.
 
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