Epson ET-8550 DTF Conversion V2 Dampers: Why White Ink Circulation Shouldn't "Suck Ink" From the Dampers

Question: I converted my Epson ET-8550 using the V2 dampers. When the white ink circulation runs, it seems like it's sucking ink out of the dampers. Is that normal, and if not, is there a solution?

Answer: 

Now to your question directly: No-this is not normal. A properly functioning white ink circulation system is meant to keep white ink moving to reduce settling, but it should not pull (vacuum) ink out of the dampers in a way that drains them, introduces air, or destabilizes the printhead feed.

When it does "suck ink from the dampers," it usually means one of a few things is happening in the fluid path.

1) What "normal" white circulation should look like

In a healthy setup:

• Circulation should create gentle flow through the white circuit (depending on the design: recirculating damper/manifold/loop).

• Dampers should stay consistently filled (not collapsing, not gulping air, not draining down).

• You should not see aggressive backflow that pulls ink away from the head feed.

If circulation is strong enough to empty dampers, the head is at risk of:

• air ingestion

• nozzle dropouts

• white printing fading or going blank intermittently

• clogs (white pigment is unforgiving once air gets involved)

2) Most common causes when circulation "pulls" ink out of dampers

Cause A: The circulation loop is pulling vacuum because of a restriction or blockage

If the return line is restricted (kinked tubing, pinched line, clogged filter, blocked check valve, or partially clogged fitting), the pump can create negative pressure in the wrong place-often upstream near the dampers.

What you might observe

• Dampers visibly draining

• Tubes showing air gaps or bubbles that keep growing

• White line flow looks uneven (surging)

Typical fixes

• Inspect every white line for kinks, tight bends, crushed tubing, or partially seated fittings

• Check any inline filters: if they're loaded with pigment, they can act like a clog

• Make sure nothing is installed backward (some components are directional)

Cause B: Check valves (one-way valves) are missing, reversed, leaking, or incorrect cracking pressure

Many DTF circulation designs depend on check valves to prevent circulation from "stealing" ink from the head feed. If a valve is reversed or leaking internally, the pump will take the easiest path-which can be straight through the dampers.

What you might observe

• Circulation seems to pull from the head side instead of the tank side

• The system won't hold prime

• You repeatedly see air re-enter after it was purged

Typical fixes

• Confirm flow direction arrows on any check valves

• Replace weak/leaky check valves (white ink can foul valves quickly)

• Use valves intended for ink flow (not generic aquarium/air valves)

Cause C: Venting/pressure imbalance in the white ink tank or reservoir

If the white tank is not venting correctly (or if it's over-venting), you can end up with the wrong pressure at the supply side. White circulation can then pull ink from where it shouldn't because the supply isn't feeding normally.

What you might observe

• Tank collapses slightly (vacuum) or bubbles constantly (over-venting)

• Ink level behavior looks strange during pump cycles

Typical fixes

• Verify the white tank vent is configured exactly as required for your setup

• Make sure caps/vents aren't clogged with dried pigment

• Avoid "sealed tank + pump" combinations unless the system is designed for it

Cause D: Damper orientation/fitment issues or micro air leaks on the suction side

A tiny air leak may not drip ink, but it can let air in whenever the pump pulls negative pressure-making it look like the circulation is sucking ink away.

Common leak points

• Loose barbed fittings

• Hairline cracks in connectors

• Tubing that's slightly oversized/undersized for the barb

• Damper seals not seated perfectly

Typical fixes

• Re-seat each connection, cut tubing ends cleanly, and reattach

• Replace any suspect connectors (even if they "look fine")

• Make sure dampers are installed in the intended orientation for V2 design

3) Why this matters more with white ink than with CMYK

White ink contains heavy pigment that settles and packs. Once you introduce air and unstable flow:

• white clogs form faster,

• dampers can lose their buffering effect,

• and you can get a cycle of "looks fine → prints fail → looks fine again," which is the worst kind of problem to chase.

So your instinct to ask is exactly right-this is a warning sign, not a normal behavior to ignore.

4) What you can do right now (practical, safe checks)

Without trying to walk you through a full remote repair, these high-level checks are generally safe and useful:

• Confirm line routing: circulation supply/return should match the intended diagram (mix-ups happen easily)

• Inspect for restrictions: kinks, pinches, clogged filter, clogged fittings

• Check valve direction and function: verify correct orientation and that it actually blocks reverse flow

• Look for air growth: if bubbles expand during circulation, that strongly suggests suction-side leak or restriction-driven vacuum

• Watch damper fill level: dampers should remain stable, not drain down during circulation cycles

If the system continues to pull ink from the dampers, it's best to stop running circulation until the fluid path is corrected-because repeated air introduction can create larger problems at the head.

Addressing printer issues can be a complicated affair due to the hands-on nature of these problems. Because of that, we're not able to provide remote troubleshooting, suggestions, or support for printer repairs. We do offer an in-person evaluation and repair service through our local diagnostic facility: Printer Repair Service (https://bchtechnologies.com/printer-repair-service). Given the high demand, we operate on a first-come, first-served basis, so it may take a few weeks before we can schedule a drop-off. Our services are structured to repair either the entire printer or specific parts, with clear instructions on how to proceed. However, we understand our rates aren't the most economical, so we strongly recommend self-help via online research. You can start by checking YouTube or visiting our channel homepage: BCH Technologies on YouTube (https://youtube.com/@bchtechnologies). Look up specific topics using the search icon next to "About" on the right-hand side of the menu bar. I receive dozens of requests every day asking for the right video, and after nine years of uploads it's difficult to remember every single one-YouTube search is the fastest method. Plus, YouTube may recommend helpful videos from other channels that relate to your exact situation.

Thank you again for reaching out. I'm glad you asked-because in a properly configured ET-8550 white circulation setup with V2 dampers, it should not be draining or "sucking ink" out of the dampers, and catching it early can prevent bigger white-ink issues later.