Bypass hose swelling

My 1/4 poly braided bypass line is swelling when it goes into bypass. I had a bigger hose but it was pulsating so I mover down in size which fixed the problem. The hose recently burst at the nipple. I after I repaired I noticed the swelling. My other machines don’t do this. I’m guessing I should get a heavier hose?
8 gpm, 3,000 psi machine.

Is it the k7 unloader?

You shouldnt use a poly braided hose for bypass

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You need pressure rated hose if you plan on using an undersized line for your flow unloader.

Personally, I prefer using a 1/2” hex plug with an appropriately sized hole drilled in the center, and installing that on the inside threads of the unloader bypass. Then I can use 1/2” hose for the bypass, and I don’t have a tornado inside my buffer tank from all that water rushing in through a tiny hose.

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If he uses a larger hose the pulsating will come back I presume.

Don’t use 1/4 hose. Another reason to use a good pressure unloader. If you don’t like instant pressure, squeeze the trigger slowly.

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@seanktm it is the K7.

@Ikii it is poly braided.

That’s why I use a hex plug with the hole drilled in it. That provides the needed back pressure to avoid pulsing/kicking.

I think I used a 1/8” bit or a little bigger. But you can use a nozzle chart to find the right sized hole for your machine. I think people recommend around 100psi or a little more on the bypass line for flow unloaders

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I saw a post where @Racer said to use one size smaller than pressure hose. Maybe I read it wrong. When I went to a bigger hose it pulsated. This might be my last K7 but not my last flow unloader.

Right, but it’s still gotta be pressure hose. Just 1/4 instead of 3/8

I missed your post earlier. Thanks for the info.

The flow is violent from the bypass. Way different than my 4 and 5.5. This is my first 8 and I built it.

Bypass shoukdnt be.
You can get a 300psi from advance auto parts.

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Thanks @Ikii.

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My K7 with the 8/3000 is fine with some yellow 3/8" 800-PSI AG hose from Sprayer Depot… I also use 3/8" pressure hose and it’s been okay so far, although it’s a pretty small sample size coming from me.

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I run the same. Never any issues.

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Dump the 1/4 inch line.

Too small, and will restrict needed flow.

I dont use k7 unloaders and never have, so I cant make too much of a judgment.

But if you have to downgrade the bypass line size to prevent pulsing, thats a no bueno in my book…

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Down sizing the hose is a fix that will work, but you can just buy the smaller orifice to put in unloader. All the distributors sell


Ah yes, I forgot to mention that when I picked up the K7 unloader from Southside, I specifically mentioned that the bypass was going back to the buffer tank and they said I need K-7.3 Flow Unloader with #2 Bypass Orifice. I just used a 3/8" ag hose the same size as the high pressure hose, and no problem yet.