K-7 Unloader Problem

[troyt 14]

I have an alkota pw that I inherited with a purchase on ebay. It was a fix me up, basically came with everything but the unloader. I ordered a K-7 unloader and installed according to the alkota specifications, and now I have a problem that I am not sure of what is causing it.

Basically when the trigger is not pulled, the K-7 unloader cycles repeatedly. It is going into bypass mode, then it seems like the uloader builds pressure, and goes back into bypass mode. I don't have any leaks, nor is the gun weeping, so I do not understand where the excess pressure is going. Any thoughts as to what could be causing this problem. When the trigger is pulled, the problem of course goes away, it is only when the unloader is in bypass mode, and not all the time. It may do it for 5 trigger pulls then on the sixth after the trigger is released not have the problem. But pull the trigger again and let go, and it starts up again.

[Celeste 341]

Troyt,

When we installed ours we had the same problem - turned out that our hose was the wrong size. We squeezed the hose ever so slightly and voila, no burping. We now have 3/8" hose (exterior diameter) attached with a barb, not a clamp. Maybe this would fix you??

Celeste

[troyt 14]

What is a barb? And which hose on the unloader did you squeeze?

[Beth n Rod 1,279]

Sounds like you need a smaller port valve on the bypass end of the unloader.

Check with a local repair shop and they can get you one.

Same problem here, changed out a K-7 with the exact same one but the port valve the manufacturer shipped in it was too large and caused the surging cycle.

The mechanic showed me the same technique to check it by squeezing the bypass line enough to restrict the flow and the surging stopped. But just as quickly, as he let it go, the cycling started back up.

Rod~

[Celeste 341]

What he said :)

Celeste

[troyt 14]

That has seemed to take care of the problem with the K-7, thanks for all your help Rod and Celeste!

[Aplus 525]

What timing. I had a K7 fail on me earlier this week. It went into total bypass. Fortunately I had a spare on hand. It still takes some work to change out all the fittings from the old to new. I did notice the bypass port valve was different, the old one was a #2, and the one on the new unloader was a #1. Different diamter holes in the fitting. Good thing I put the old one back on.

[troyt 14]

Quick question, Ok the K7 I have is the K7.1 version. Now I am trying to figure out the specific nipple size I need, because this is supposed to be the correct unloader. How can I figure my gpm if I know I have 3000 psi, and a 8hp electric motor? Is there a mathmatical tool for this?

[Russ Johnson 141]

What model pump is on the machine?

[One Tough Pressure 580]

And I have the same surging that just started out of the blue. I have no air leaks on the inlet, no weeping of the gun and the bypass hose is the same one that has been there for a long time.

This is third K7 I have put on since April of 04. What gives, why do they fail so quick? What is a good pressure type unloader to switch over to?

[VanDiesel99 14]

I had that problem for a few minutes, then The unloader would not kick in to bypass. I took the allen bolts out of the blunt end, then popped that "pin" out. Its felt like is wasn't lubricated well so I placed a drop of motor oil on it and rubbed it on. Haven't had any problems since.

[Beth n Rod 1,279]

And I have the same surging that just started out of the blue. I have no air leaks on the inlet, no weeping of the gun and the bypass hose is the same one that has been there for a long time.

This is third K7 I have put on since April of 04. What gives, why do they fail so quick? What is a good pressure type unloader to switch over to?

Particles in the system such as a piece of calcium or scale for example that gets stuck in the unloader and causes a change in its flow parameter. This will cause it to cycle until either the peice dissolves enough to flow through the system or when you physically remove it.

Rod~

[Aplus 525]

It wouldn't hurt to open up the K7 and give the innards a good cleaning and lubrication.

[Jim Carroll 14]

to find out gpms---5-10 gallon pail and watch, run for a minute

i had same prob with k7, dropped orifice size down by 1 number.

[Washaway 64]

I know that most of us are all aware of the avaiable redundancy in the name of safety but I thought that this link was interesting none the less.

And maybe there's someone out there that can learn from it.

http://www.arnorthamerica.com/unloader.html

[Beth n Rod 1,279]

Thank you for the link :)

Every little bit helps!

Rod~

[R L S 14]

Heres a tid bit of info the K-7 I got from Larry Hinckley at Delco. When you are trying to find the correct orifice wheter it be bypass or outlet. Always go one size smaller than the chart recommends. The folks in Italy or wherever they are made wont change the way they chart the sizes. FYI

Richard

[One Tough Pressure 580]

I have taken my old K7's apart for inspection and they both looked fine. I will have to take this last one apart and see what might be in there.

For the time being, I will use a Giant pressure type unloader and see how I like that kick.

Each time I replaced my K7, it was the unloader only, I used the same fittings that were on the first one that came with the machine, so there is no question that I had the right one.

The surging stopped almost as fast as it came so i guess there was a small piece of junk in there that cleared itself. Either way, I was low on pressure, so it needed to be replaced asap.