Kellogg American Unloader Valve Sticking

[justgurn]

The other day I was doing some plasma work and the unloader valve stuck open several times. After a few cycles it corrected itself. Has anyone took theirs apart and cleaned it? I think it is just a spring loaded ball valve, but I don't know if it has an adjustable tension. The compressor is a 331TVA.

 

[Major Ramifications]

When you say it stuck open, what exactly were the symptoms?
Was air coming out while the pump was running?
Was air continuing to come out after the motor shut off?

 

[justgurn]

Major Ramifications
Yes to both questions. When it first occurred the compressor shut off, the unloader started to blowoff and didn't close for a couple cycles. Before it corrected itself.

 

[Trey T]

I have never worked on a KA centrifugal unloader but I would imagine it's not any harder than the one with shrader valve type unloader.

I would open it up and inspect it or clean it.

 

[justgurn]

Trey T
I've never worked on one before. Open it through the hex cap or the cast housing?

 

[b-body-bob]

If it's like a Champion and it looks like it might be, there's a pin inside there that is either pushed in or not by the centrifugal weights on the snout of the crankshaft. You might be able to clean it up without taking it apart there with that nut at the very nose of it.

Also, if I understand everything I know about a compressor, it could be a defective tank check valve pressurizing the unloader and causing it to blow off too.

 

[justgurn]

b boby bob, This is scary, I understand what you're saying.

 

[Todd.Brock]

If the unloader is faulty, I would expect to hear air coming out while the pump is running. If air is coming out more than a few seconds after the pump shuts off, the I would look at the check valve. The unloader is designed to bleed off pressure between the check valve and head. So if it's bleeding off while running, then the unloader may be sticking from dirt, gunk, oil sludge , etc as others have stated. I have had a compressor with centrifugal unloader, but never had to work with them. My guess is the weights keep the valve shut while running and then the valve opens when the weights slow down from the pump cutting off.

Take note how they come apart or google it. I doubt centrifugal unloader a are wildy complicated.

 

[Trey T]

the hex cap facing out. Like other front "cast housing" or "unloader housing" (Saylor Beall or Campbell Hausfield), there's only the weight/plunger assembly behind it. It sounds to me the devices behind the "unloader housing" functions normally.

If youre afraid of the air pressure, drain the tank first b4 servicing.

Trey T
I've never worked on one before. Open it through the hex cap or the cast housing?

 

[justgurn]

Thanks for the advice. I will put the healing to it the morning.
jg

 

[justgurn]

Well I didn't wait. I removed the hex cap, removed the spring and ball. Sprayed cleaner till rusty residue came out clear. Depressed pin and sprayed cleaner till rusty residue came out clear.Put it back together. I got a cut project to work on tomorrow that should test it out. Thanks again guys! Jg

 

[mmouse]

331's are nice pumps. I used to have one, but never took the unloader apart. If it has a check ball in it, you can give it a tap with a brass drift to help seat the ball.

 

[Fixnair]

There is a brass valve body under the hex cap. When you remove the hex cap you will see a spring. Under the spring and inside the valve body is a ball. I would not try to remove the brass valve body. They are usually frozen in place. If you absolutely have to remove it, remove the whole cover from the compressor, extract the ball and pushrod, and heat the brass valve body with a torch. Not so hot that you melt the threads. Just hot enough to boil spit, about 250-300*. Now toss the the whole thing into a pail of water. The brass will shrink faster than the iron and break the bond. It should screw out pretty easy.

If the valve leaks while the compressor is shut off in means the check valve is leaking. Follow the discharge pipe from the compressor to the tank. Your check valve is probably that hex device screwed into the tank at the end of your discharge pipe.